Do not use magic numbers, do not prefix stuff with "PCI_", do not
declare registers in implementation files. Also move the PCI
registers under correct comment in i915_reg.h.

v2:
- Consistently use BSM (not BDSM or other variants from PRM) (Chris)
- Also include register address to help identify the register (Chris)
v3:
- Refer to register value as *_val instead of *_reg (Chris)
v4:
- Make style checker happy

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Use the connector type instead of VBT directly to decide which backlight
mechanism to use on VLV/CHV. (Indirectly, this is the same thing, but
hides the VBT use.)
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458125015-7931-5-git-send-email-jani.nikula@intel.com

Supposedly we would want to get the PWM output as close as possible to
the target, so let's round to closest.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Suggested-by: NJani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1456932138-14004-7-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Generalize rawclk handling by storing it in dev_priv.

Presumably our hrawclk readout works at least for CTG and ELK
since we've been using it for DP AUX on those platforms. There
are no real docs anymore after configdb vanished, so the only
reference is the public CTG GMCH spec. What bits are listed in
that doc match our code. The ELK GMCH spec have no relevant
details unfortunately.

The PNV situation is less clear. Starting from
commit aa17cdb4 ("drm/i915: initialize backlight max from VBT")
we assume that the CTG/ELK hrawclk readout works for PNV as well.
At least the results *seem* reasonable for one PNV machine (Lenovo
Ideapad S10-3t). Sadly the PNV GMCH spec doesn't have the goods on
the relevant register either.

So let's keep assuming it works for PNV,ELK,CTG and read it out on
those platforms. G33 also has hrawclk according to some notes
in BSpec, but we don't actually need it for anything, so let's not
even try to read it out there.

v2: Rebase due to IS_VALLYVIEW vs. IS_CHERRYVIEW split
    Use KHz() all over, and kill off a few useless temp variables
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1456932138-14004-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Use dev_priv rather than dev pointer where applicable. Remove plenty of
unnecessary temp variables. No functional changes.
Reviewed-by: NMika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450428695-28831-1-git-send-email-jani.nikula@intel.com

Use the for_each_intel_* macros for iterating intel_encoder,
intel_connector, and intel_crtc. No functional changes.
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450262896-5325-1-git-send-email-jani.nikula@intel.com

The cherryview device shares many characteristics with the valleyview
device.  When support was added to the driver for cherryview, the
corresponding device info structure included .is_valleyview = 1.
This is not correct and leads to some confusion.

This patch changes .is_valleyview to .is_cherryview in the cherryview
device info structure and simplifies the IS_CHERRYVIEW macro.
Then where appropriate, instances of IS_VALLEYVIEW are replaced with
IS_VALLEYVIEW || IS_CHERRYVIEW or equivalent.

v2: Use IS_VALLEYVIEW || IS_CHERRYVIEW instead of defining a new macro.
    Also add followup patches to fix issues discovered during the first
    review. (Ville)
v3: Fix some style issues and one gen check. Remove CRT related changes
    as CRT is not supported on CHV. (Imre, Ville)
v4: Make a few more optimizations. (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: NWayne Boyer <wayne.boyer@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449692975-14803-1-git-send-email-wayne.boyer@intel.comReviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: NJani Nikula <jani.nikula@intel.com>

No need to read out cdclk from the hardware, we have it already
cached in dev_priv.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448893432-6978-7-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

We have HAS_PCH_LPT_LP() already, so add HAS_PCH_LPT_H() and use it
where appropriate.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448893432-6978-4-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

CTG uses hrawclk for backlight, so calculate the max based on that
instead of cdclk.

Fixes: aa17cdb4 ("drm/i915: initialize backlight max from VBT")
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448893432-6978-3-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

Convert the MHz number coming from intel_rawclk() into Hz in
i9xx_hz_to_pwm() on PNV. Otherwise we'll get something totally
bogus as a result.

Fixes: aa17cdb4 ("drm/i915: initialize backlight max from VBT")
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448893432-6978-2-git-send-email-ville.syrjala@linux.intel.comReviewed-by: NJani Nikula <jani.nikula@intel.com>

If the backlight modulation frequency can't be extracted from the
registers or from VBT, use 200 Hz as the default. This may enable
backlight on some machines that previously failed.
Reviewed-by: NImre Deak <imre.deak@intel.com>
Tested-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448958232-26520-2-git-send-email-jani.nikula@intel.com

The only missing piece is the function to convert frequency to PWM
register value. The PWM is based on 19.2 MHz clock, except for BXT A
step, which is based on CDCLK, and which we ignore.
Reviewed-by: NImre Deak <imre.deak@intel.com>
Tested-by: NImre Deak <imre.deak@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1448958232-26520-1-git-send-email-jani.nikula@intel.com

Although we don't support or enable CPU PWM with LPT/SPT based systems,
it may have been enabled prior to loading the driver. Disable the CPU
PWM on LPT/SPT backlight disable to avoid warnings on LCPLL disable.

The issue has been present on BDW since BDW enabling, but was recently
introduced on HSW with

commit 437b15b8
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Fri Sep 4 16:55:13 2015 +0300

    drm/i915: use pch backlight override on hsw too

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reference: http://mid.gmane.org/87y4frhwsn.fsf@yhuang-dev.intel.comReported-by: Nkernel test robot <ying.huang@intel.com>
Tested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1446033429-8006-1-git-send-email-jani.nikula@intel.com

i915 expects the OpRegion to be cached (i.e. not __iomem), so explicitly
map it with memremap rather than the implied cache setting of
acpi_os_ioremap().

Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: NDan Williams <dan.j.williams@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Latest VBT mentions which set of registers will be used for BLC,
as controller number field. Making use of this field in BXT
BLC implementation. Also, the registers are used in case control
pin indicates display DDI. Adding a check for this.
According to Bspec, BLC_PWM_*_2 uses the display utility pin for output.
To use backlight 2, enable the utility pin with mode = PWM
   v2: Jani's review comments
   addressed
       - Add a prefix _ to BXT BLC registers definitions.
       - Add "bxt only" comment for u8 controller
       - Remove control_pin check for DDI controller
       - Check for valid controller values
       - Set pipe bits in UTIL_PIN_CTL
       - Enable/Disable UTIL_PIN_CTL in enable/disable_backlight()
       - If BLC 2 is used, read active_low_pwm from UTIL_PIN polarity
   Satheesh's review comment addressed
       - If UTIL PIN is already enabled, BIOS would have programmed it. No
       need to disable and enable again.
   v3: Jani's review comments
       - add UTIL_PIN_PIPE_MASK and UTIL_PIN_MODE_MASK
       - Disable UTIL_PIN if controller 1 is used
       - Mask out UTIL_PIN_PIPE_MASK and UTIL_PIN_MODE_MASK before enabling
       UTIL_PIN
       - check valid controller value in intel_bios.c
       - add backlight.util_pin_active_low
       - disable util pin before enabling
   v4: Change for BXT-PO branch:
   Stubbed unwanted definition which was existing before
   because of DC6 patch.
   UTIL_PIN_MODE_PWM     (0x1b << 24)

v2: Fixed Jani's review comment.

v3: Split the backight PWM frequency programming into separate patch,
    in cases BIOS doesn't initializes it.

v4: Starting afresh and not modifying existing state for backlight, as
    per Jani's recommendation.

v5: Fixed Jani's review comment wrt util pin enable
Signed-off-by: NVandana Kannan <vandana.kannan@intel.com>
Signed-off-by: NSunil Kamath <sunil.kamath@intel.com>
Signed-off-by: NUma Shankar <uma.shankar@intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Previously we've relied on having basically one backlight and one
backlight type per platform. This is already a bit quirky with PMIC PWM
support on VLV/CHV platforms with MIPI DSI. In the foreseeable future
we'll have at least DPCD based backlight control on eDP and DCS command
based backlight control on MIPI DSI. Backlight is becoming more and more
connector specific, so reflect this fact by making the backlight control
hooks connector specific.

This enables further work to reuse generic backlight code in
intel_panel.c while adding more specific backlight code accessed via the
hooks.

Cc: Deepak M <m.deepak@intel.com>
Cc: Yetunde Adebisi <yetundex.adebisi@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NDeepak M <m.deepak@intel.com>
Reviewed-by: NYetunde Adebisi <yetundex.adebisi@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Make adjusted_mode const whereever we don't have to modify it. This only
covers cases when we have a local adjusted_mode variable, and doesn't
make any difference for cases where we just dereference
pipe_config->adjusted_mode.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMika Kahola <mika.kahola@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The adjustead_mode crtc_ timings are what we will program into the hardware,
so it's those timings we should be looking practically everywhere.

The normal and crtc_ timings should differ only when stere doubling is
used. In that case the normal timings are the orignal non-doubled
timigns, and crtc_ timings are the doubled timings used by the hardware.

The only case where we continue to look at the normal timings is when we
pass the adjusted_mode to drm_match_{cea,hdmi}_mode() to find the VIC.
drm_edid keeps the modes aronund in the non-double form only, so it
needs the non-double timings to match against.

Done with sed
's/adjusted_mode->\([vhVH]\)/adjusted_mode->crtc_\1/g'
's/adjusted_mode->clock/adjusted_mode->crtc_clock/g'
with a manual s/VDisplay/vdisplay/ within the comment in intel_dvo.c

v2: Update due to intel_dsi.c changes
Reviewed-by: NMika Kahola <mika.kahola@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Rename the function argument to 'adjusted_mode' whenever the function
only ever gets passed the adjusted_mode.

v2: Update due to intel_dsi.c changes
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NMika Kahola <mika.kahola@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently everyone and their dog has their own favourite spelling
for vga_switcheroo. This makes it hard to grep dmesg for log entries
relating to vga_switcheroo. It also makes it hard to find related
source files in the tree.

vga_switcheroo.c uses pr_fmt "vga_switcheroo". Use that everywhere.
Signed-off-by: NLukas Wunner <lukas@wunner.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Fall back to VBT based backlight modulation frequency if it's not
set. Do not hard code.

This could be a problem if there is no VBT.

Cc: Clint Taylor <clinton.a.taylor@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Tested-by: NClint Taylor <Clinton.A.Taylor@intel.com>
Reviewed-by: NClint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Normally we determine the backlight PWM modulation frequency (which we
also use as backlight max value) from the backlight registers at module
load time, expecting the registers have been initialized by the BIOS. If
this is not the case, we fail.

The VBT contains the backlight modulation frequency in Hz. Add platform
specific functions to convert the frequency in Hz to backlight PWM
modulation frequency, and use them to initialize the backlight when the
registers are not initialized by the BIOS.

v2: Fix SPT and VLV. Thanks to Clint for the VLV code.

Cc: Clint Taylor <clinton.a.taylor@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NClint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently the difference between backlight control on HSW vs. BDW/SKL is
that on HSW we modify the duty cycle on the CPU register, and have the
hardware pass the changes on to the PCH registers. We still drive the
PCH PWM on both. While HSW and BDW use the same LPT PCH, BDW does not
pass these messages on to the PCH. Therefore on BDW we need to enable
the PCH override bit, and program the PCH directly. (On SPT PCH, this
mode is the default.) We could as well do this on HSW too, and in fact
I've been told this is what a certain other operating system does. So
use PCH backlight override on HSW too.

This simplifies some follow-up code, but it does have the danger of
breaking backlight on HSW machines. It should work, but mysterious are
the ways of backlight.

While at it, name the related backlight hooks according to the PCH
rather than the CPU for clarity.

Cc: Clint Taylor <clinton.a.taylor@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NClint Taylor <Clinton.A.Taylor@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Use the CRC PWM device in intel_panel.c and add new MIPI backlight
specififc callbacks

v2: Modify to use pwm_config callback
v3: Addressed Jani's comments
    - Renamed all function as pwm_* instead of vlv_*
    - Call intel_panel_actually_set_backlight in enable function
    - Return -ENODEV in case pwm_get fails
    - in case pwm_config error return error cdoe from pwm_config
    - Cleanup pwm in intel_panel_destroy_backlight
v4: Removed unused #defines and initialized backlight with INVALID_PIPE (Ville)

CC: Samuel Ortiz <sameo@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NShobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Some 855gm models (at least ThinkPad X40) regressed because of

commit b0cd324f
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Wed Nov 12 16:25:43 2014 +0200

    drm/i915: don't save/restore backlight hist ctl registers

which tried to make our driver more robust by not blindly saving and
restoring registers, but it failed to take into account

commit 0eb96d6e
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Wed Oct 14 12:33:41 2009 -0700

    drm/i915: save/restore BLC histogram control reg across suspend/resume

Fix the regression by enabling hist ctl on gen2.

v2: Improved the comment.

v3: Improved the comment, again.
Reported-and-tested-by: NPhilipp Gesang <phg@phi-gamma.net>
References: http://mid.gmane.org/20150623222648.GD12335@acheron
Fixes: b0cd324f ("drm/i915: don't save/restore backlight hist ctl registers")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

Enabling BLC on BXT.
Includes register definition, and new functions for BXT.

In BXT, there are 2 sets of registers for BLC. Until there is clarity
about which set would be effective, set 1 is being used.
This would have to be re-visited if there is any change or when 2 LFPs are
enabled on BXT.

This patch enables brightness change which would be effected by use of
hot-keys or sysfs entry.

TODO:- BLC implementation will have to re-visited when
1. there is clarity about which set of registers has to be used and when.
2. CDCLK frequency is changed

v2: Jani's review comments
	- Modified comment in i915_reg.h
	- Renamed register defintions
	- Removed definition of duty cycle max. Not required now and its not 64-bit.

v3:
  - Rebase on top of VLV/CHV backlight changes, in particuliar
    bxt_set_backlight() now has a different prototype (Damien)
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NVandana Kannan <vandana.kannan@intel.com>
Signed-off-by: NDamien Lespiau <damien.lespiau@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Shankar, Uma <uma.shankar@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We have grown a number of different implementations of
DIV_ROUND_CLOSEST_ULL throughout the kernel.  Move the i915 one to
kernel.h so that it can be reused.
Signed-off-by: NJavi Merino <javi.merino@arm.com>
Reviewed-by: NJeff Epler <jepler@unpythonic.net>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Guenter Roeck <linux@roeck-us.net>
Acked-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Alex Elder <elder@linaro.org>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Javi Merino <javi.merino@arm.com>
Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

And get rid of the duplicate mode structures. This patch was generated
with the following semantic patch:

@@ @@
struct intel_crtc_state {
+struct drm_crtc_state base;
+
...
-struct drm_display_mode requested_mode;
-struct drm_display_mode adjusted_mode;
...
}
@@ struct intel_crtc_state *state; @@
-state->adjusted_mode
+state->base.adjusted_mode
@@ struct intel_crtc_state *state; @@
-state->requested_mode
+state->base.mode
@@ struct intel_crtc_state state; @@
-state.adjusted_mode
+state.base.adjusted_mode
@@ struct intel_crtc_state state; @@
-state.requested_mode
+state.base.mode
@@ struct drm_crtc *crtc; @@
-to_intel_crtc(crtc)->config.adjusted_mode
+to_intel_crtc(crtc)->config.base.adjusted_mode
@@ identifier member; expression E; @@
-PIPE_CONF_CHECK_FLAGS(adjusted_mode.member, E);
+PIPE_CONF_CHECK_FLAGS(base.adjusted_mode.member, E);
@@ identifier member; @@
-PIPE_CONF_CHECK_I(adjusted_mode.member);
+PIPE_CONF_CHECK_I(base.adjusted_mode.member);
@@ identifier member; @@
-PIPE_CONF_CHECK_CLOCK_FUZZY(adjusted_mode.member);
+PIPE_CONF_CHECK_CLOCK_FUZZY(base.adjusted_mode.member);

v2: Completely generate the patch with cocci. (Ander)
Signed-off-by: NAnder Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

The objective is to make this structure usable with the atomic helpers,
so let's start with the rename. Patch generated with coccinelle:

@@ @@
-struct intel_crtc_config {
+struct intel_crtc_state {
...
}
@@ @@
-struct intel_crtc_config
+struct intel_crtc_state

v2: Completely generate the patch with cocci. (Ander)
Signed-off-by: NAnder Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: NMatt Roper <matthew.d.roper@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

commit 6dda730e
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Tue Jun 24 18:27:40 2014 +0300

    drm/i915: respect the VBT minimum backlight brightness

introduced a bug which resulted in inconsistent brightness levels on
different machines. If a suspended was entered with the screen off some
machines would resume with the screen at minimum brightness and others
at maximum brightness.

The following commands can be used to produce this behavior.

  xset dpms force off
  sleep 1
  sudo systemctl suspend
  (resume ...)

The root cause of this problem is a comparison which checks to see if
the backlight level is zero when the panel is enabled.  If it is zero,
it is set to the maximum level.  Unfortunately, not all machines have a
minimum level of zero. On those machines the level is left at the
minimum instead of begin set to the maximum.

Fix the bug by updating the comparison to check for the minimum
backlight level instead of zero.  Also, expand the comparison for
the possible case when the level is less than the minimum.

Fixes: 6dda730e ("respect the VBT minimum backlight brightness")
Signed-off-by: NJeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

Now that the backlight device no longer gets registered too early we
should be able to drop most of the INVALID_PIPE checks from the backlight
code.

The only exceptio is the opregion stuff where we may (in theory at
least) get a request from the BIOS already during driver init as soon as
the backlight setup has been done. In which case we can still get the
INVALID_PIPE from intel_get_pipe_from_connector(). So leave that check
in place, and add a comment explaining why.

For the rest, if we still manage to get here with INVALID_PIPE on
VLV/CHV we will now get a WARN from the lower level functions and
can then actually investigate further.

v2: Leave the check in the BIOS related code (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Currently we register the backlight device as soon as we register the
connector. That means we can get backlight requests from userspace
already before reading out the current modeset hardware state.

That means we don't yet know the current crtc->encoder->connector mapping,
which causes problems for VLV/CHV which need to know the current pipe in
order to figure out which BLC registers to poke. Currently we just
ignore such requests fairly deep in the backlight code which means the
backlight device brightness property will get out of sync with our
backlight.level and the actual hardware state.

Fix the problem by delaying the backlight device registration until the
entire modeset init has been performed. And we also move the
backlight unregisteration to happen as the first thing during the
modeset cleanup so that we also won't be bothered with userspace
backlight requested during teardown.

This is a real world problem on machines using systemd, because systemd,
for some reason, wants to restore the backlight to the level it used last
time. And that happens as soon as it sees the backlight device appearing
in the system. Sometimes the userspace access makes it through before
the modeset init, sometimes not.

v2: Do not lie to the user in the debug prints (Jani)
    Include connector name in the prints (Jani)
    Fix a typo in the commit message (Jani)
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

On VLV/CHV both pipes A and B have their own backlight control
registers. In order to correctly read out the current hardware state at
init we need to know which pipe is driving the eDP port. Pass that
information down from the eDP init code into the backlight code.

To determine the correct pipe we first look at which pipe is currently
configured in the port control register, if that look invalid we look
at which pipe's PPS is currently controlling the port, and if that
too looks invalid we just assume pipe A.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

On VLV/CHV when the display is off, we can't read out the current
backlight level from the hardware since we have no pipe to do so.
Currently we end up reading a bigus register due to passing
INVALID_PIPE to VLV_BLC_PWM_CTL().

Skip the entire .get_backlight() call if the backlight isn't enabled
according to backlight.enabled.

This problem can be reproduced simply by reading the backlight device
actual_brightness file while the display is off.

Cc: Jani Nikula <jani.nikula@intel.com>
Suggested-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

VLV/CHV have backlight controls only on pipes A and B. Bail out
without touching registers that don't exist, and print a warning.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Never trust (your interpretation of) the VBT. Regression from

commit 6dda730e
Author: Jani Nikula <jani.nikula@intel.com>
Date:   Tue Jun 24 18:27:40 2014 +0300

    drm/i915: respect the VBT minimum backlight brightness

causing div by zero if VBT minimum brightness equals maximum brightness.

Despite my attempts I've failed in my detective work to figure out what
the root cause is. This is not the real fix, but we have to do
something.
Reported-by: NMike Auty <mike.auty@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=86551
Cc: stable@vger.kernel.org (v3.17+)
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

SPT is always in the PCH override mode, and the bit MBZ. Only set
override on LPT.

v2: check for PCH version (Ville)
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Move the duplicated DIV_ROUND_CLOSEST_ULL macro into the intel_drv.h
header file so that it can be shared between intel_display.c
and intel_panel.c.
Signed-off-by: NU. Artie Eoff <ullysses.a.eoff@intel.com>
Reviewed-By: NJoe Konno <joe.konno@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Improper truncated integer division in the scale() function causes
actual_brightness != brightness. This (partial) work-around should be
sufficient for a majority of use-cases, but it is by no means a complete
solution.

TODO: Determine how best to scale "user" values to "hw" values, and
vice-versa, when the ranges are of different sizes. That would be a
buggy scenario even with this work-around.

The issue was introduced in the following (v3.17-rc1) commit:

    6dda730e drm/i915: respect the VBT minimum backlight brightness

Note that for easier backporting this commit adds a duplicated macro.
A follow-up cleanup patch rectifies this for 3.18+

v2: (thanks to Chris Wilson) clarify commit message, use rounded division
macro

v3: -DIV_ROUND_CLOSEST() fails to build with CONFIG_X86_32=y. (Jani)
    -Use DIV_ROUND_CLOSEST_ULL() instead. (Damien)
    -v1 and v2 originally authored by Joe Konno.
Signed-off-by: NU. Artie Eoff <ullysses.a.eoff@intel.com>
Cc: stable@vger.kernel.org
Reviewed-By: NJoe Konno <joe.konno@intel.com>
[danvet: Add backporting note.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>