When parsing the structures in the shared memory, there are values which
come from the remote device.  For example, a transfer completion event
will have a pointer to the tre in the relevant channel's transfer ring.
As another example, event ring elements may specify a channel in which
the event occurred, however the specified channel value may not be valid
as no channel is defined at that index even though the index may be less
than the maximum allowed index.  Such values should be considered to be
untrusted, and validated before use.  If we blindly use such values, we
may access invalid data or crash if the values are corrupted.

If validation fails, drop the relevant event.
Signed-off-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Link: https://lore.kernel.org/r/1615411855-15053-1-git-send-email-jhugo@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

When device enters flash programmer context (FP), it exposes firehose
protocol through the EDL dedicated channels.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617784860-32439-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Deinit the device on shutdown to halt MHI/PCI operation on device
side. This change fixes floating device state with some hosts that
do not fully shutdown PCIe device when rebooting.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1616169037-7969-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

The mhi_prepare_for_transfer() and mhi_unprepare_from_transfer()
APIs could use better explanation. Add details on what MHI does
when these APIs are used.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-10-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

The __mhi_unprepare_channel() API does not require the __ prefix.
Get rid of it and make the internal function consistent with the
other function names.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Link: https://lore.kernel.org/r/1617311778-1254-9-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

A client can attempt to unprepare certain channels for transfer even
after the execution environment they are supposed to run in has changed.
In the event that happens, the device need not be notified of the reset
and the host can proceed with clean up for the channel context and
memory allocated for it on the host as the device will no longer be able
to respond to such a request.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-8-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

When clearing up the channel context after client drivers are
done using channels, the configuration is currently not being
reset entirely. Ensure this is done to appropriately handle
issues where clients unaware of the context state end up calling
functions which expect a context.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-7-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

MHI host can fail early if device is in a bad state by attempting
to assert device wake and holding the runtime PM vote before
sending a channel update command instead of performing a wake
toggle and waiting for a timeout if the send were to fail. This
can help improve the design and enable shorter wait periods for
device to respond as votes are already held.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-6-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Debug messages dealing with client devices use the generic MHI
controller or parent device along with a channel number. It would
be better to instead use the client device directly and enable
better log messages for channel updates.
Suggested-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-5-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Improve the channel handling state machine such that all commands
go through a common function and a validation process to ensure
that the state machine is not violated in any way and adheres to
the MHI specification. Using this common function allows MHI to
eliminate some unnecessary debug messages and code duplication.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-4-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

If a channel was explicitly stopped but not reset and a driver
remove is issued, clean up the channel context such that it is
reflected on the device. This move is useful if a client driver
module is unloaded or a device crash occurs with the host having
placed the channel in a stopped state.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-3-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Add support to allow sending the STOP channel command. If a
client driver would like to STOP a channel and have the device
retain the channel context instead of issuing a RESET to it and
clearing the context, this would provide support for it after
the ability to send this command is exposed to clients.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-2-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Add generic info for SDX65 based modems.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1617399199-35172-1-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Some controllers can choose to skip preparation for power up.
In that case, device context is initialized based on the pre_init
flag not being set during mhi_prepare_for_power_up(). There is no
reason MHI host driver should maintain and provide controllers
with two separate paths for preparing MHI.

Going forward, all controllers will be required to call the
mhi_prepare_for_power_up() API followed by their choice of sync
or async power up. This allows MHI host driver to get rid of the
pre_init flag and sets up a common way for all controllers to use
MHI. This also helps controllers fail early on during preparation
phase in some failure cases.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617313309-24035-1-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Since M3 can be entered/exited quite a lot when used for runtime PM,
keep the mhi suspend/resume transitions quiet.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617700315-12492-2-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

This change ensures that PM reference is always get during packet
queueing and released either after queuing completion (RX) or once
the buffer has been consumed (TX). This guarantees proper update for
underlying MHI controller runtime status (e.g. last_busy timestamp)
and prevents suspend to be triggered while TX packets are flying,
or before we completed update of the RX ring.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617700315-12492-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

In certain devices, it is likely that there is no incoming MHI
interrupt for a transition to MHI READY state. One such example
is the move from Pass Through to an SBL or AMSS execution
environment. In order to facilitate faster bootup times as there
is no need to wait until timeout_ms completes, MHI host can poll
every 25 milliseconds to check if device has entered MHI READY
until a maximum timeout of twice the timeout_ms is reached.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617215665-19593-3-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Introduce helper function to allow MHI core driver to poll for
a value in a register field. This helps reach a common path to
read and poll register values along with a retry time interval.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617215665-19593-2-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

As of now abbreviations are being used for many state and
execution environment strings. Improve and expand those such that
debug messages are clear.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-8-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

When moving from SYS_ERROR transition to a different execution
environment, MHI host relies on the BHI register read to spawn
the next image download or wait for READY -> M0 states. The
device can at times move the execution environment to mission
mode when a pass through is expected, which can result in a
stall. Initiate a wait for MHI READY and write M0 such that the
device can proceed with state change event updates for any new
execution environment being entered. This allows us to remove
conditionals in handling firmware load for PBL modes and keeps
the execution environment out of the picture as it can change at
any time.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-7-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

MHI power up can go through an EDL to Flash Programmer path when
the device has a blank NAND. In those cases, mhi_sync_power_up()
can timeout waiting for a mission mode execution environment.
Allow a successful power up instead by identifying Flash
Programmer as a valid mission mode execution environment with a
purpose to flash the device image contents.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-6-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

MHI WWAN modems support downloading firmware to NAND or eMMC
using Firehose protocol with process as follows:
1. Modem boots up, enters AMSS execution environment and the
device later enters EDL (Emergency Download) mode through any
mechanism host can use such as a diag command.
2. Modem enters SYS_ERROR, MHI host handles SYS_ERROR transition.
3. EDL image for device to enter 'Flash Programmer' execution
environment is then flashed via BHI interface from host.
4. Modem enters MHI READY -> M0 and sends the Flash Programmer
execution environment change to host.
5. Following that, EDL/FIREHOSE channels (34, 35) are made
available from the host.
6. User space tool for downloading firmware image to modem over
the EDL channels using Firehose protocol. Link to USB flashing
tool: https://git.linaro.org/landing-teams/working/qualcomm/qdl.git/

Make the necessary changes to allow for this sequence to occur and
allow using the Flash Programmer execution environment.
Signed-off-by: NCarl Yin <carl.yin@quectel.com>
Co-developed-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-5-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Device entering EDL or Emergency Download Mode will be in a
SYS_ERROR MHI state. This requires MHI host to proceed with the
EDL image download over BHI before device can enter an MHI READY
state and proceed with further bootup. Allow this to be handled
by relying on the execution environment check after SYS_ERROR
processing to determine whether to wait for an MHI READY or
download the EDL image over BHI after moving MHI PM state to
Power on Reset internally. This way handling is contained well
within the MHI core driver and helps pave the way for Flash
Programmer execution environment functionality.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-4-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Currently, the firmware load handler returns after the EDL image
is downloaded. Wait for an MHI READY transition instead as the
specification expects so as to proceed with further bootup such
as device entering Flash Programmer execution environment.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-3-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Relying on the current execution environment to determine if EDL
image was downloaded should not be done as the execution
environment can change at this point in error cases and we may
misread it. Instead, MHI can rely on the local 'fw_name' variable
as a safer alternative.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1617067704-28850-2-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

We cannot process a power_down if the power state is DISABLED.  There is
no valid mhi_ctxt in that case, so attepting to process the power_down
will likely result in a null pointer dereference.  If the power state is
DISABLED, there is nothing to do anyways, so just bail early.
Signed-off-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1615409365-8165-1-git-send-email-jhugo@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Currently ENOMEM is returned when MHI ring is full. This error code is
very misleading. Change to EAGAIN instead.
Signed-off-by: NFan Wu <wufan@codeaurora.org>
Signed-off-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1615408803-7016-1-git-send-email-jhugo@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

The variables state and ee are being initialized with values that
are never read and are being updated later with a new values. The
initializations are redundant and can be removed.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <mani@kernel.org>
Addresses-Coverity: ("Unused value")
Link: https://lore.kernel.org/r/20210311111727.8433-1-colin.king@canonical.comSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Some controllers can opt to not have MHI download a firmware
image to have the device bootup and can find the device in a
pass through execution environment, ready to go. Thus, MHI
controllers for those devices do not need fw_image defined.
Make it optional to accommodate different bootup modes.
Suggested-by: NLoic Poulain <loic.poulain@linaro.org>
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1615315595-37750-1-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

The check to see if we have reset the device after detecting syserr at
power_up is inverted.  wait_for_event_timeout() returns 0 on failure,
and a positive value on success.  The check is looking for non-zero
as a failure, which is likely to incorrectly cause a device init failure
if syserr was detected at power_up.  Fix this.

Fixes: e18d4e9f ("bus: mhi: core: Handle syserr during power_up")
Signed-off-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1613165243-23359-1-git-send-email-jhugo@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Update debug prints to include local device in the BHI interrupt
handler. This helps show transitions better between MHI states.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1614208985-20851-5-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

In current design, whenever the BHI interrupt is fired, the
execution environment is updated. This can cause race conditions
and impede ongoing power up/down processing. For example, if a
power down is in progress, MHI host updates to a local "disabled"
execution environment. If a BHI interrupt fires later, that value
gets replaced with one from the BHI EE register. This impacts the
controller as it does not expect multiple RDDM execution
environment change status callbacks as an example. Another issue
would be that the device can enter mission mode and the execution
environment is updated, while device creation for SBL channels is
still going on due to slower PM state worker thread run, leading
to multiple attempts at opening the same channel.

Ensure that EE changes are handled only from appropriate places
and occur one after another and handle only PBL modes or RDDM EE
changes as critical events directly from the interrupt handler.
Simplify handling by waiting for SYS ERROR before handling RDDM.
This also makes sure that we use the correct execution environment
to notify the controller driver when the device resets to one of
the PBL execution environments.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614208985-20851-4-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

During full boot chain firmware download, the PM state worker
downloads the AMSS image after a blocking wait for the SBL
execution environment change when running in PBL transition
itself. Improve this design by having the host download the AMSS
image from the SBL transition of PM state worker thread when a
DEV_ST_TRANSITION_SBL is queued instead of the blocking wait.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Link: https://lore.kernel.org/r/1614208985-20851-3-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Currently, client devices are created in SBL or AMSS (mission
mode) and only destroyed after power down or SYS ERROR. When
moving between certain execution environments, such as from SBL
to AMSS, no clean-up is required. This presents an issue where
SBL-specific channels are left open and client drivers now run in
an execution environment where they cannot operate. Fix this by
expanding the mhi_destroy_device() to do an execution environment
specific clean-up if one is requested. Close the gap and destroy
devices in such scenarios that allow SBL client drivers to clean
up once device enters mission mode.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NHemant Kumar <hemantk@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614208985-20851-2-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

MHI suspend/resume are symmetric and balanced procedures. If device is
not in M3 state on a resume, that means something happened behind our
back. In this case resume is aborted and error reported, to let the
controller handle the situation.

This is mainly requested for system wide suspend-resume operation in
PCI context which may lead to power-down/reset of the controller which
will then lose its MHI context. In such cases, PCI driver is supposed
to recover and reinitialize the device.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614960841-20233-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

As per documentation, fields marked as (required) in an MHI
controller structure need to be populated by the controller driver
before calling mhi_register_controller(). Ensure all required
pointers and non-zero fields are present in the controller before
proceeding with the registration.
Signed-off-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1615315490-36017-1-git-send-email-bbhatt@codeaurora.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Use MHI controller device name instead of the 'bus' device name as
debugfs dir name (e.g. /sys/kernel/debug/mhi0). That aligns with
sysfs device name.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Tested-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: NJeffrey Hugo <jhugo@codeaurora.org>
Link: https://lore.kernel.org/r/1613403753-1457-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

mhi_queue returns an error when the doorbell is not accessible in
the current state. This can happen when the device is in non M0
state, like M3, and needs to be waken-up prior ringing the DB. This
case is managed earlier by triggering an asynchronous M3 exit via
controller resume/suspend callbacks, that in turn will cause M0
transition and DB update.

So, since it's not an error but just delaying of doorbell update, there
is no reason to return an error.

This also fixes a use after free error for skb case, indeed a caller
queuing skb will try to free the skb if the queueing fails, but in
that case queueing has been done.

Fixes: a8f75cb3 ("mhi: core: Factorize mhi queuing")
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NJeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614336782-5809-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

A recent change created a dedicated workqueue for the state-change work
with WQ_HIGHPRI (no strong reason for that) and WQ_MEM_RECLAIM flags,
but the state-change work (mhi_pm_st_worker) does not guarantee forward
progress under memory pressure, and will even wait on various memory
allocations when e.g. creating devices, loading firmware, etc... The
work is then not part of a memory reclaim path...

Moreover, this causes a warning in check_flush_dependency() since we end
up in code that flushes a non-reclaim workqueue:

[   40.969601] workqueue: WQ_MEM_RECLAIM mhi_hiprio_wq:mhi_pm_st_worker [mhi] is flushing !WQ_MEM_RECLAIM events_highpri:flush_backlog
[   40.969612] WARNING: CPU: 4 PID: 158 at kernel/workqueue.c:2607 check_flush_dependency+0x11c/0x140
[   40.969733] Call Trace:
[   40.969740]  __flush_work+0x97/0x1d0
[   40.969745]  ? wake_up_process+0x15/0x20
[   40.969749]  ? insert_work+0x70/0x80
[   40.969750]  ? __queue_work+0x14a/0x3e0
[   40.969753]  flush_work+0x10/0x20
[   40.969756]  rollback_registered_many+0x1c9/0x510
[   40.969759]  unregister_netdevice_queue+0x94/0x120
[   40.969761]  unregister_netdev+0x1d/0x30
[   40.969765]  mhi_net_remove+0x1a/0x40 [mhi_net]
[   40.969770]  mhi_driver_remove+0x124/0x250 [mhi]
[   40.969776]  device_release_driver_internal+0xf0/0x1d0
[   40.969778]  device_release_driver+0x12/0x20
[   40.969782]  bus_remove_device+0xe1/0x150
[   40.969786]  device_del+0x17b/0x3e0
[   40.969791]  mhi_destroy_device+0x9a/0x100 [mhi]
[   40.969796]  ? mhi_unmap_single_use_bb+0x50/0x50 [mhi]
[   40.969799]  device_for_each_child+0x5e/0xa0
[   40.969804]  mhi_pm_st_worker+0x921/0xf50 [mhi]

Fixes: 8f703978 ("bus: mhi: core: Move to using high priority workqueue")
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NBhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614161930-8513-1-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

When the device is idle it is possible to move it into the lowest MHI
PM state (M3). In that mode, all MHI operations are suspended and the
PCI device can be safely put into PCI D3 state.

The device is then resumed from D3/M3 either because of host initiated
MHI operation (e.g. buffer TX) or because the device (modem) has
triggered wake-up via PME feature (e.g. on incoming data).

Same procedures can be used for system wide or runtime suspend/resume.
Signed-off-by: NLoic Poulain <loic.poulain@linaro.org>
Reviewed-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614971808-22156-6-git-send-email-loic.poulain@linaro.orgSigned-off-by: NManivannan Sadhasivam <manivannan.sadhasivam@linaro.org>