On Fri, Dec 02, 2016 at 02:27:43PM +0100, Hans de Goede wrote: > Hi, > > On 02-12-16 13:40, Ville Syrjälä wrote: > > On Thu, Dec 01, 2016 at 04:39:57PM +0100, Hans de Goede wrote: > >> On my Cherrytrail CUBE iwork8 Air tablet PIPE-A would get stuck on loading > >> i915 at boot 1 out of every 3 boots, resulting in a non functional LCD. > >> Once the i915 driver has successfully loaded, the panel can be disabled / > >> enabled without hitting this issue. > >> > >> The getting stuck is caused by vlv_init_display_clock_gating() clearing > >> the DPOUNIT_CLOCK_GATE_DISABLE bit in DSPCLK_GATE_D when called from > >> chv_pipe_power_well_ops.enable() on driver load, while PIPE-A is enabled > >> driving the DSI LCD by the BIOS. > >> > >> Clearing this bit while DSI is in use is a known issue and > >> intel_dsi_pre_enable() / intel_dsi_post_disable() already set / clear it > >> as appropriate. > >> > >> This commit modifies vlv_init_display_clock_gating() to leave the > >> DPOUNIT_CLOCK_GATE_DISABLE bit alone fixing PIPE-A getting stuck. > >> > >> BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=97330 > >> Cc: stable@xxxxxxxxxxxxxxx > >> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >> --- > >> drivers/gpu/drm/i915/intel_runtime_pm.c | 13 ++++++++++++- > >> 1 file changed, 12 insertions(+), 1 deletion(-) > >> > >> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c > >> index 356c662..b5ce7cb 100644 > >> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c > >> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c > >> @@ -1039,7 +1039,18 @@ static bool vlv_power_well_enabled(struct drm_i915_private *dev_priv, > >> > >> static void vlv_init_display_clock_gating(struct drm_i915_private *dev_priv) > >> { > >> - I915_WRITE(DSPCLK_GATE_D, VRHUNIT_CLOCK_GATE_DISABLE); > >> + u32 val; > >> + > >> + /* > >> + * When on driver load, PIPE A may be active and driving a DSI display. > >> + * Preserve DPOUNIT_CLOCK_GATE_DISABLE to avoid PIPE A getting stuck > >> + * (and never recovering) in this case. intel_dsi_post_disable() will > >> + * clear it when we turn off the display. > > > > Why are you talking only about pipe A here? > > Because that is the pipe which was getting stuck on my tablet. I see that > the comment for the same workaround in intel_dsi.c just says: > " Disable DPOunit clock gating, can stall pipe" so I guess I should > update the comment s/PIPE A/pipe(s)/. Any other remarks before I send a v2 ? Nope. With that this is Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > Regards, > > Hans > > > > > > >> + */ > >> + val = I915_READ(DSPCLK_GATE_D); > >> + val &= DPOUNIT_CLOCK_GATE_DISABLE; > >> + val |= VRHUNIT_CLOCK_GATE_DISABLE; > >> + I915_WRITE(DSPCLK_GATE_D, val); > >> > >> /* > >> * Disable trickle feed and enable pnd deadline calculation > >> -- > >> 2.9.3 > >> > >> _______________________________________________ > >> dri-devel mailing list > >> dri-devel@xxxxxxxxxxxxxxxxxxxxx > >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- Ville Syrjälä Intel OTC _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
