On Wed, Jun 20, 2012 at 09:17:41AM +0200, Takashi Iwai wrote: > This patch fixes the problem on some HP desktop machines with eDP > which give blank screens after S3 resume. > > The problem looks like a timing issue. Although BLC_PWM_CPU_CTL > register is already restored at the beginning of resume, it doesn't > seem to take effect. Simply re-issuing the register write restores > the backlight gracefully. > > Tested with 3.5-rc3 kernel. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49233 > > Signed-off-by: Takashi Iwai <tiwai at suse.de> This patch looks very fishy as-is, simply because I don't like adding random calls to random functions at pretty much random places without any hint why it works. Just a few weeks ago we've had tons of fun with writes that don't stick when the ring isn't yet set up. Can you please check with a bunch of printks what exactly happens to the value of BLC_PWM_CPU_CTL? I.e. whether the write doesn't stick or whether it gets reset somewhere between the register restore functions and the new place. I suspect the opregion_init call could allow the bios to frob with these registers. If that's the case, the patch is missing a comment that to that effect. Essentially I want to know why this place here works and why not move the call a few lines up or down. -Daniel > --- > drivers/gpu/drm/i915/i915_drv.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c > index 9fe9ebe..2ba1350 100644 > --- a/drivers/gpu/drm/i915/i915_drv.c > +++ b/drivers/gpu/drm/i915/i915_drv.c > @@ -658,6 +658,9 @@ static int i915_drm_thaw(struct drm_device *dev) > > intel_opregion_init(dev); > > + if (dev_priv->backlight) > + backlight_update_status(dev_priv->backlight); > + > dev_priv->modeset_on_lid = 0; > > console_lock(); > -- > 1.7.10.4 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx at lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Daniel Vetter Mail: daniel at ffwll.ch Mobile: +41 (0)79 365 57 48
