On Thu, 2013-11-14 at 12:14 +0200, Jani Nikula wrote: > The quirk was added as what I'd say was a stopgap measure in > > commit e85843bec6c2ea7c10ec61238396891cc2b753a9 > Author: Kamal Mostafa <[email protected]> > Date: Fri Jul 19 15:02:01 2013 -0700 > > drm/i915: quirk no PCH_PWM_ENABLE for Dell XPS13 backlight > > without really digging into what was going on. > > Also, as mentioned in the related bug [1], having the quirk regressed > some of the machines it was supposed to fix to begin with, and there > were patches posted to disable the quirk on such machines [2]! > > The fact is, we do need the BLM_PCH_PWM_ENABLE bit set to have > backlight. With the quirk, we've relied on BIOS to have set it, and our > save/restore code to retain it. With the full backlight setup at enable, > we have no place for things that rely on previous state. > > With the per platform hooks, we've also made a change in the PCH > platform enable order: setting the backlight duty cycle between CPU and > PCH PWM enable. Some experimenting and > > commit 770c12312ad617172b1a65b911d3e6564fc5aca8 > Author: Takashi Iwai <[email protected]> > Date: Sat Aug 11 08:56:42 2012 +0200 > > drm/i915: Fix blank panel at reopening lid > > indicate that we can't set the backlight before enabling CPU PWM; the > value just won't stick. But AFAICT we should do it before enabling the > PCH PWM. > > Finally, any fallout we should fix properly, preferrably without quirks, > and absolutely without quirks that rely on existing state. With the per > platform hooks have much more flexibility to adjust the sequence as > required by platforms. > > [1] https://bugzilla.kernel.org/show_bug.cgi?id=47941 > [2] > http://lkml.kernel.org/r/[email protected] > > Signed-off-by: Jani Nikula <[email protected]>
Thanks for the explanation: Reviewed-by: Imre Deak <[email protected]> > --- > drivers/gpu/drm/i915/i915_drv.h | 1 - > drivers/gpu/drm/i915/intel_display.c | 16 ---------------- > drivers/gpu/drm/i915/intel_panel.c | 4 ---- > 3 files changed, 21 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index c243b8e..e726ab9 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -717,7 +717,6 @@ enum intel_sbi_destination { > #define QUIRK_PIPEA_FORCE (1<<0) > #define QUIRK_LVDS_SSC_DISABLE (1<<1) > #define QUIRK_INVERT_BRIGHTNESS (1<<2) > -#define QUIRK_NO_PCH_PWM_ENABLE (1<<3) > > struct intel_fbdev; > struct intel_fbc_work; > diff --git a/drivers/gpu/drm/i915/intel_display.c > b/drivers/gpu/drm/i915/intel_display.c > index 25ef080..b9f763c 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -10456,17 +10456,6 @@ static void quirk_invert_brightness(struct > drm_device *dev) > DRM_INFO("applying inverted panel brightness quirk\n"); > } > > -/* > - * Some machines (Dell XPS13) suffer broken backlight controls if > - * BLM_PCH_PWM_ENABLE is set. > - */ > -static void quirk_no_pcm_pwm_enable(struct drm_device *dev) > -{ > - struct drm_i915_private *dev_priv = dev->dev_private; > - dev_priv->quirks |= QUIRK_NO_PCH_PWM_ENABLE; > - DRM_INFO("applying no-PCH_PWM_ENABLE quirk\n"); > -} > - > struct intel_quirk { > int device; > int subsystem_vendor; > @@ -10526,11 +10515,6 @@ static struct intel_quirk intel_quirks[] = { > * seem to use inverted backlight PWM. > */ > { 0x2a42, 0x1025, PCI_ANY_ID, quirk_invert_brightness }, > - > - /* Dell XPS13 HD Sandy Bridge */ > - { 0x0116, 0x1028, 0x052e, quirk_no_pcm_pwm_enable }, > - /* Dell XPS13 HD and XPS13 FHD Ivy Bridge */ > - { 0x0166, 0x1028, 0x058b, quirk_no_pcm_pwm_enable }, > }; > > static void intel_init_quirks(struct drm_device *dev) > diff --git a/drivers/gpu/drm/i915/intel_panel.c > b/drivers/gpu/drm/i915/intel_panel.c > index 0986472..da088e3 100644 > --- a/drivers/gpu/drm/i915/intel_panel.c > +++ b/drivers/gpu/drm/i915/intel_panel.c > @@ -749,10 +749,6 @@ static void pch_enable_backlight(struct intel_connector > *connector) > pch_ctl2 = panel->backlight.max << 16; > I915_WRITE(BLC_PWM_PCH_CTL2, pch_ctl2); > > - /* XXX: transitional */ > - if (dev_priv->quirks & QUIRK_NO_PCH_PWM_ENABLE) > - return; > - > pch_ctl1 = 0; > if (panel->backlight.active_low_pwm) > pch_ctl1 |= BLM_PCH_POLARITY;
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