It is not necessary to share the same notifier.h.
Signed-off-by: NWANG Cong <amwang@redhat.com>
Cc: David Miller <davem@davemloft.net>
Acked-by: N"Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At http://www.mail-archive.com/linux-mmc@vger.kernel.org/msg08371.html
(thread: "mmc: sdio: reset card during power_restore") we found and
fixed a bug where mmc's runtime power management functions were not being
called. We have now also made improvements to the SDIO powerup routine
which could possibly mask this kind of issue in future.

Add debug messages to the runtime PM hooks so that it is easy to verify
if and when runtime PM is happening.
Signed-off-by: NDaniel Drake <dsd@laptop.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Previously there has only been one function mmc_wait_for_req()
to start and wait for a request. This patch adds:

 * mmc_start_req() - starts a request wihtout waiting
   If there is on ongoing request wait for completion
   of that request and start the new one and return.
   Does not wait for the new command to complete.

This patch also adds new function members in struct mmc_host_ops
only called from core.c:

 * pre_req - asks the host driver to prepare for the next job
 * post_req - asks the host driver to clean up after a completed job

The intention is to use pre_req() and post_req() to do cache maintenance
while a request is active. pre_req() can be called while a request is
active to minimize latency to start next job. post_req() can be used after
the next job is started to clean up the request. This will minimize the
host driver request end latency. post_req() is typically used before
ending the block request and handing over the buffer to the block layer.

Add a host-private member in mmc_data to be used by pre_req to mark the
data. The host driver will then check this mark to see if the data is
prepared or not.
Signed-off-by: NPer Forlin <per.forlin@linaro.org>
Acked-by: NKyungmin Park <kyungmin.park@samsung.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Reviewed-by: NVenkatraman S <svenkatr@ti.com>
Tested-by: NSourav Poddar <sourav.poddar@ti.com>
Tested-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Some host controllers will not operate without a hardware
timeout that is limited in value.  However large discards
require large timeouts, so there needs to be a way to
specify the maximum discard size.

A host controller driver may now specify the maximum discard
timeout possible so that max_discard_sectors can be calculated.

However, for eMMC when the High Capacity Erase Group Size
is not in use, the timeout calculation depends on clock
rate which may change.  For that case Preferred Erase Size
is used instead.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

The erase timeout calculation may depend on clock rate
which is zero if the clock is gated, so use
mmc_host_clk_rate() which allows for that case.
Signed-off-by: NAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

mmc_rescan_try_freq() tries to init two times with the last frequency.
For example, if host->f_min is 400KHz, we see the message below:

mmc1: mmc_rescan_try_freq: trying to init card at 400000 Hz
mmc1: mmc_rescan_try_freq: trying to init card at 400000 Hz

Andy Ross says that he didn't try this code on a board with an f_min
that exactly matches one of the table entries, which explains why the
bug wasn't detected.
Signed-off-by: NJaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Cc: Andy Ross <andy.ross@windriver.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

eMMC voltage change not required for 1.8V.  3.3V and 1.8V vcc
are capable of doing DDR. vccq of 1.8v is not required.
Signed-off-by: NPhilip Rakity <prakity@marvell.com>
Reviewed-by: NArindam Nath <arindam.nath@amd.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

eMMC chips do not use CMD11 when changing voltage.  Add extra
argument to call to indicate if CMD11 needs to be sent.
Signed-off-by: NPhilip Rakity <prakity@marvell.com>
Reviewed-by: NArindam Nath <arindam.nath@amd.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Since the MMC_PM_KEEP_POWER flag should be set on each suspend,
it should also cleared on each resume.

Upon resuming, we have to know if power was kept
(for re-initialization, etc.), so clear it just after resuming.
Signed-off-by: NEliad Peller <eliad@wizery.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

This patch adds support for setting driver strength during UHS-I
initialization procedure. Since UHS-I cards set S18A (bit 24) in
response to ACMD41, we use this as a base for UHS-I initialization.
We modify the parameter list of mmc_sd_get_cid() so that we can
save the ROCR from ACMD41 to check whether bit 24 is set.

We decide whether the Host Controller supports A, C, or D driver
type depending on the Capabilities register. Driver type B is
suported by default. We then set the appropriate driver type for
the card using CMD6 mode 1. As per Host Controller spec v3.00, we
set driver type for the host only if Preset Value Enable in the
Host Control2 register is not set. SDHCI_HOST_CONTROL has been
renamed to SDHCI_HOST_CONTROL1 to conform to the spec.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.
Signed-off-by: NArindam Nath <arindam.nath@amd.com>
Reviewed-by: NPhilip Rakity <prakity@marvell.com>
Tested-by: NPhilip Rakity <prakity@marvell.com>
Acked-by: NZhangfei Gao <zhangfei.gao@marvell.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Host Controller v3.00 adds another Capabilities register. Apart
from other things, this new register indicates whether the Host
Controller supports SDR50, SDR104, and DDR50 UHS-I modes. The spec
doesn't mention about explicit support for SDR12 and SDR25 UHS-I
modes, so the Host Controller v3.00 should support them by default.
Also if the controller supports SDR104 mode, it will also support
SDR50 mode as well. So depending on the host support, we set the
corresponding MMC_CAP_* flags. One more new register. Host Control2
is added in v3.00, which is used during Signal Voltage Switch
procedure described below.

Since as per v3.00 spec, UHS-I supported hosts should set S18R
to 1, we set S18R (bit 24) of OCR before sending ACMD41. We also
need to set XPC (bit 28) of OCR in case the host can supply >150mA.
This support is indicated by the Maximum Current Capabilities
register of the Host Controller.

If the response of ACMD41 has both CCS and S18A set, we start the
signal voltage switch procedure, which if successfull, will switch
the card from 3.3V signalling to 1.8V signalling. Signal voltage
switch procedure adds support for a new command CMD11 in the
Physical Layer Spec v3.01. As part of this procedure, we need to
set 1.8V Signalling Enable (bit 3) of Host Control2 register, which
if remains set after 5ms, means the switch to 1.8V signalling is
successfull. Otherwise, we clear bit 24 of OCR and retry the
initialization sequence. When we remove the card, and insert the
same or another card, we need to make sure that we start with 3.3V
signalling voltage. So we call mmc_set_signal_voltage() with
MMC_SIGNAL_VOLTAGE_330 set so that we are back to 3.3V signalling
voltage before we actually start initializing the card.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.
Signed-off-by: NArindam Nath <arindam.nath@amd.com>
Reviewed-by: NPhilip Rakity <prakity@marvell.com>
Tested-by: NPhilip Rakity <prakity@marvell.com>
Acked-by: NZhangfei Gao <zhangfei.gao@marvell.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Converts from:
	struct mmc_request mrq;
	memset(&mrq, 0, sizeof(struct mmc_request));

to:
	struct mmc_request mrq = {0};

because it's shorter, as performant, and easier to work out whether
initialization has happened.
Signed-off-by: NChris Ball <cjb@laptop.org>

Converts from:
	struct mmc_command cmd;
	memset(&cmd, 0, sizeof(struct mmc_command));

to:
	struct mmc_command cmd = {0};

because it's shorter, as performant, and easier to work out whether
initialization has happened.
Signed-off-by: NChris Ball <cjb@laptop.org>

Renames erase_timeout to cmd_timeout_ms inside struct mmc_command.
First step to making host honor timeouts for non-data-transfer
commands. Cleans up erase timeout code.
Signed-off-by: NAndrei Warkentin <andreiw@motorola.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

mmc_card_is_powered_resumed is a mouthful; instead, simply use
mmc_card_keep_power, which also better explains the purpose of
the macro.

Employ mmc_card_keep_power() where possible.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

At power off, reset OCR mask to be the highest possible voltage
supported for the current mmc host.

This solves the re-initialization during the power up sequence.
The voltage may have been decreased due to the card accepts a lower
voltage than the voltage used during the initialization sequence.
We need to reset the voltage to by the host highest possible value
since according to specification the initialization must always be
done at high voltage.
Reviewed-by: NJonas Aberg <jonas.aberg@stericsson.com>
Signed-off-by: NUlf Hansson <ulf.hansson@stericsson.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

When using mmc_try_claim_host the corresponding release
function is mmc_do_release_host, which then also must
be exported.
Reviewed-by: NJonas Aberg <jonas.aberg@stericsson.com>
Reviewed-by: NSebastian Rasmussen <sebastian.rasmussen@stericsson.com>
Signed-off-by: NUlf Hansson <ulf.hansson@stericsson.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

sdio_reset sends a CMD52 to reset the sdio card.  This is highly
recommended for sdio cards being reinitialized.  Since we do not
know if the card is being reinitialized we just send the command.
SD/eMMC cards are supposed to ignore the CMD before the CMD0.
Document why we are doing this.
Signed-off-by: NPhilip Rakity <prakity@marvell.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

Since mmc clock gating can also be used as a power gating
tip, it's better to put the led blinking after having
ungated the clock.
Signed-off-by: NPierre Tardy <pierre.tardy@intel.com>
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

30201e7f ("mmc: skip detection of nonremovable cards on rescan")
allowed skipping detection of nonremovable cards on mmc_rescan().
The intention was to only skip detection of hardwired cards that
cannot be removed, so make sure this is indeed the case by directly
checking for (lack of) MMC_CAP_NONREMOVABLE, instead of using
mmc_card_is_removable(), which is overloaded with
CONFIG_MMC_UNSAFE_RESUME semantics.

The user-visible symptom of the bug this patch fixes is that no
"mmc: card XXXX removed" message appears in dmesg when a card is
removed and CONFIG_MMC_UNSAFE_RESUME=y.
Reported-and-tested-by: NDmitry Shmidt <dimitrysh@google.com>
Reported-and-tested-by: NMaxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

The card is not always clocked and the clock frequency zero is perfectly
legal, thus this code in mmc_set_data_timeout() may cause a division by
zero. It will be triggered more often if you're using software clock
gating but can be triggered under other conditions too.
Reported-by: NPierre Tardy <tardyp@gmail.com>
Signed-off-by: NLinus Walleij <linus.walleij@stericsson.com>
Reviewed-by: NChris Ball <cjb@laptop.org>
Cc: <stable@kernel.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Signed-off-by: NChris Ball <cjb@laptop.org>

Rewrite and clean up mmc_rescan() to properly retry frequencies lower
than 400kHz.  Failures can happen both in sd_send_* calls and
mmc_attach_*.  Break out "mmc_rescan_try_freq" from the frequency
selection loop.  Symmetrize claim/release logic in mmc_attach_* API,
and move the sd_send_* calls there to make mmc_rescan easier to read.
Signed-off-by: NAndy Ross <andy.ross@windriver.com>
Reviewed-and-Tested-by: NHein Tibosch <hein_tibosch@yahoo.es>
Reviewed-by: NChris Ball <cjb@laptop.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

In case of failure, mmc_attach_sdio() will power off the SD bus.
Power it up and reinitialize before trying SD memory detection.
Reported-by: NSahitya Tummala <stummala@codeaurora.org>
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: NChris Ball <cjb@laptop.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Initial SDIO runtime PM implementation took a conservative approach
of powering up cards (and fully reinitializing them) on system suspend,
just before the suspend handlers of the relevant drivers were executed.

To avoid redundant power and reinitialization cycles, this patch removes
this behavior: if a card is already powered off when system suspend kicks
in, it is left at that state.

If a card is active when a system sleep starts, everything is
straightforward and works exactly like before. But if the card was
already suspended before the sleep began, then when the MMC core powers
it back up on resume, its run-time PM status has to be updated to reflect
the actual post-system sleep status.

The technique to do that is borrowed from the I2C runtime PM
implementation (for more info see Documentation/power/runtime_pm.txt).
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Reviewed-by: NChris Ball <cjb@laptop.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

mmc_rescan() checks whether registered cards are still present before
skipping them, by calling the bus-specific ->detect() handler.

With buses that support runtime PM, the card may be powered off at
this point, so they need to be powered on and fully reinitialized before
->detect() executes.

This whole process is redundant with nonremovable cards; in those cases,
we can safely skip calling ->detect() and implicitly assume its success.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Reviewed-by: NChris Ball <cjb@laptop.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

This patch modifies the MMC core code to optionally call the set_ios()
operation on the driver with the clock frequency set to 0 (gate) after
a grace period of at least 8 MCLK cycles, then restore it (ungate)
before any new request. This gives the driver the option to shut down
the MCI clock to the MMC/SD card when the clock frequency is 0, i.e.
the core has stated that the MCI clock does not need to be generated.

It is inspired by existing clock gating code found in the OMAP and
Atmel drivers and brings this up to the host abstraction.  Gating is
performed before and after any MMC request.

This patchset implements this for the MMCI/PL180 MMC/SD host controller,
but it should be simple to switch OMAP/Atmel over to using this instead.

mmc_set_{gated,ungated}() add variable protection to the state holders
for the clock gating code.  This is particularly important when ordinary
.set_ios() calls would race with the .set_ios() call resulting from a
delayed gate operation.
Signed-off-by: NLinus Walleij <linus.walleij@stericsson.com>
Reviewed-by: NChris Ball <cjb@laptop.org>
Tested-by: NChris Ball <cjb@laptop.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Workqueue creation API has been updated and flush_scheduled_work() is
deprecated and scheduled to be removed.

* core/core.c: Use alloc_ordered_workqueue() instead of
  create_singlethread_workqueue().  This removes an unnecessary
  rescuer.

* host/omap.c: Create, use and flush mmc_omap_wq instead of the
  system_wq.

* Flush host->mmc_carddetect_work directly on removal instead of using
  flush_scheduled_work().
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Chris Ball <cjb@laptop.org>
Cc: linux-mmc@vger.kernel.org

In the error-path where PM notifies PM_POST_RESTORE, the rescan-blockage
should be cleared as well.  Otherwise it'll be never re-probed.

Also, as a bonus, this fixes a bug in S4 with user-mode suspend in the
current code, as it sends PM_POST_RESTORE instead of
PM_POST_HIBERNATION wrongly.

Cc: <stable@kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NChris Ball <cjb@laptop.org>

MMC hosts that poll for card detection by defining the MMC_CAP_NEEDS_POLL
flag have a race on rmmod, where the delayed work is cancelled without
waiting for completed polling. To prevent this a _sync version of the work
cancellation has to be used.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: <stable@kernel.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

Allow power save/restore and their relevant mmc_bus_ops handlers
exit with a return value.
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Tested-by: NLuciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

One flaw with DDR support is that MMC core does not inform the driver
which DDR mode it has selected.  This patch expands the ios->ddr flag
to do that.
Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

The DDR support patch needs the following fixes:

- The block driver does not need to know about DDR, any more
  than it needs to know about bus width.
- Not only the card must be switched to DDR mode.  The host
  controller must also be configured, which is done through
  the 'set_ios()' function.
- Do not set the DDR mode state until after the switch command
  is successful.
- Setting block length is not supported in DDR mode.  Make that
  a core function and change the other place it is used (mmc_test)
  also.
Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: NChris Ball <cjb@laptop.org>

After discovering a problem in regulator reference counting I took Mark
Brown's advice to move the reference count into the MMC core by making the
regulator status a member of struct mmc_host.

I took this opportunity to also implement NULL versions of
the regulator functions so as to rid the driver code from
some ugly #ifdef CONFIG_REGULATOR clauses.
Signed-off-by: NLinus Walleij <linus.walleij@stericsson.com>
Reviewed-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Liam Girdwood <lrg@slimlogic.co.uk>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Adrian Hunter <adrian.hunter@nokia.com>
Cc: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: Sundar Iyer <sundar.iyer@stericsson.com>
Cc: Daniel Mack <daniel@caiaq.de>
Cc: Pierre Ossman <pierre@ossman.eu>
Cc: Matt Fleming <matt@console-pimps.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Eric Miao <eric.y.miao@gmail.com>
Cc: Cliff Brake <cbrake@bec-systems.com>
Cc: Jarkko Lavinen <jarkko.lavinen@nokia.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

mmc_rescan() includes a pr_info which prints 4 lines each second for
hosts configured with MMC_CAP_NEEDS_POLL. This patch enables the message
only if CONFIG_MMC_DEBUG is selected. Tested on i.MX51's sdhci-esdhc.
Signed-off-by: NEric Bénard <eric@eukrea.com>
Acked-by: NWolfram Sang <w.sang@pengutronix.de>
Acked-by: NHein Tibosch <hein_tibosch@yahoo.es>
Signed-off-by: NChris Ball <cjb@laptop.org>

In the latest releases of the mmc driver, the freq during initialization
is set to a fixed 400 Khz.  This was reportedly too fast for several
users.  As there doesn't seem to be an ideal frequency
which-works-for-all, Pierre suggested to let the driver try several
frequencies.

This patch implements that idea. It will try mmc-initialization using
several frequencies from an array 400, 300, 200 and 100.

In case SDIO is broken, it'll still try to detect SDMEM, also at different
freqs.
Signed-off-by: NHein Tibosch <hein_tibosch@yahoo.es>
Cc: Pierre Ossman <pierre@ossman.eu>
Reviewed-by: NChris Ball <cjb@laptop.org>
Tested-by: NChris Ball <cjb@laptop.org>
Cc: Ben Nizette <bn@niasdigital.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Adrian Hunter <adrian.hunter@nokia.com>
Cc: Matt Fleming <matt@console-pimps.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NChris Ball <cjb@laptop.org>

There are two checks that need to be made when determining whether a
card is removable. A host controller may set MMC_CAP_NONREMOVABLE if the
controller does not support removing cards (e.g. eMMC), in which case
the card is physically non-removable. Also the 'mmc_assume_removable'
module parameter can be configured at module load time, in which case
the card may be logically non-removable.

A helper function keeps the logic in one place so that code always
checks both conditions.

Because this new function is likely to be called from modules we now
need to export the mmc_assume_removable symbol.
Signed-off-by: NMatt Fleming <matt@console-pimps.org>
Acked-by: NKyungmin Park <kyungmin.park@samsung.com>
Tested-by: NJaehoon Chung <jh80.chung@samsung.com>
Acked-by: NWolfram Sang <w.sang@pengutronix.de>
Signed-off-by: NChris Ball <cjb@laptop.org>

Fix SDIO suspend/resume regression introduced by 4c2ef25f "mmc: fix
all hangs related to mmc/sd card insert/removal during suspend/resume":

  PM: Syncing filesystems ... done.
  Freezing user space processes ... (elapsed 0.01 seconds) done.
  Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
  Suspending console(s) (use no_console_suspend to debug)
  pm_op(): platform_pm_suspend+0x0/0x5c returns -38
  PM: Device pxa2xx-mci.0 failed to suspend: error -38
  PM: Some devices failed to suspend

4c2ef25f moved the card removal/insertion mechanism out of MMC's
suspend/resume path and into pm notifiers (mmc_pm_notify), and that
broke SDIO's expectation that mmc_suspend_host() will remove the card,
and squash the error, in case -ENOSYS is returned from the bus suspend
handler (mmc_sdio_suspend() in this case).

mmc_sdio_suspend() is using this whenever at least one of the card's SDIO
function drivers does not have suspend/resume handlers - in that case
it is agreed to force removal of the entire card.

This patch fixes this regression by trivially bringing back that part of
mmc_suspend_host(), which was removed by 4c2ef25f.
Reported-and-tested-by: NSven Neumann <s.neumann@raumfeld.com>
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: <stable@kernel.org>
Acked-by: NNicolas Pitre <nico@fluxnic.net>
Signed-off-by: NChris Ball <cjb@laptop.org>

SD/MMC cards tend to support an erase operation.  In addition, eMMC v4.4
cards can support secure erase, trim and secure trim operations that are
all variants of the basic erase command.

SD/MMC device attributes "erase_size" and "preferred_erase_size" have been
added.

"erase_size" is the minimum size, in bytes, of an erase operation.  For
MMC, "erase_size" is the erase group size reported by the card.  Note that
"erase_size" does not apply to trim or secure trim operations where the
minimum size is always one 512 byte sector.  For SD, "erase_size" is 512
if the card is block-addressed, 0 otherwise.

SD/MMC cards can erase an arbitrarily large area up to and
including the whole card.  When erasing a large area it may
be desirable to do it in smaller chunks for three reasons:

    1. A single erase command will make all other I/O on the card
       wait.  This is not a problem if the whole card is being erased, but
       erasing one partition will make I/O for another partition on the
       same card wait for the duration of the erase - which could be a
       several minutes.

    2. To be able to inform the user of erase progress.

    3. The erase timeout becomes too large to be very useful.
       Because the erase timeout contains a margin which is multiplied by
       the size of the erase area, the value can end up being several
       minutes for large areas.

"erase_size" is not the most efficient unit to erase (especially for SD
where it is just one sector), hence "preferred_erase_size" provides a good
chunk size for erasing large areas.

For MMC, "preferred_erase_size" is the high-capacity erase size if a card
specifies one, otherwise it is based on the capacity of the card.

For SD, "preferred_erase_size" is the allocation unit size specified by
the card.

"preferred_erase_size" is in bytes.
Signed-off-by: NAdrian Hunter <adrian.hunter@nokia.com>
Acked-by: NJens Axboe <axboe@kernel.dk>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Madhusudhan Chikkature <madhu.cr@ti.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Ben Gardiner <bengardiner@nanometrics.ca>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If you don't use CONFIG_MMC_UNSAFE_RESUME, as soon as you attempt to
suspend, the card will be removed, therefore this patch doesn't change the
behavior of this option.

However the removal will be done by pm notifier, which runs while
userspace is still not frozen and thus can freely use del_gendisk, without
the risk of deadlock which would happen otherwise.

Card detect workqueue is now disabled while userspace is frozen, Therefore
if you do use CONFIG_MMC_UNSAFE_RESUME, and remove the card during
suspend, the removal will be detected as soon as userspace is unfrozen,
again at the moment it is safe to call del_gendisk.

Tested with and without CONFIG_MMC_UNSAFE_RESUME with suspend and hibernate.

[akpm@linux-foundation.org: clean up function prototype]
[akpm@linux-foundation.org: fix CONFIG_PM-n linkage, small cleanups]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NMaxim Levitsky <maximlevitsky@gmail.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>