Hi Clint, nice debugging! On Thu, Jun 07, 2018 at 04:12:39PM -0700, clinton.a.taylor@xxxxxxxxx wrote: > From: Clint Taylor <clinton.a.taylor@xxxxxxxxx> > > On GLK NUC platforms the HDMI retiming buffer needs additional disabled > time to correctly sync to a faster incoming signal. > When measured on a scope the highspeed lines of the HDMI clock turn > off for ~400uS during a normal resolution change. The HDMI retimer on > the GLK NUC appears to require at least a full frame of quiet time > before a new faster clock can be correctly sync'd. > The worst case scenario appears to be 23.98Hz modes which requires a > wait of 41.25ms. Add a quirk to the driver for GLK NUC that waits > 42ms. Just to understand better the failure mode: IIUC without the WA the HDMI clock line is inactive for ~400us when switching modes (which would depend on kernel timing) and the retimer chip needs at least 42ms idle time at least when switching to certain modes. Is there a way to recover the chip from the bad state? By doing a new off/on modeset with enough idle time, or resetting the chip? --Imre > > Cc: Imre Deak <imre.deak@xxxxxxxxx> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105887 > Signed-off-by: Clint Taylor <clinton.a.taylor@xxxxxxxxx> > --- > drivers/gpu/drm/i915/i915_drv.h | 1 + > drivers/gpu/drm/i915/intel_ddi.c | 8 ++++++++ > drivers/gpu/drm/i915/intel_display.c | 14 ++++++++++++++ > 3 files changed, 23 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index c407366..628491d 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -645,6 +645,7 @@ enum intel_sbi_destination { > #define QUIRK_BACKLIGHT_PRESENT (1<<3) > #define QUIRK_PIN_SWIZZLED_PAGES (1<<5) > #define QUIRK_INCREASE_T12_DELAY (1<<6) > +#define QUIRK_INCREASE_DDI_DISABLED_TIME (1<<7) > > struct intel_fbdev; > struct intel_fbc_work; > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c > index b344e0f..61b41c3 100644 > --- a/drivers/gpu/drm/i915/intel_ddi.c > +++ b/drivers/gpu/drm/i915/intel_ddi.c > @@ -1784,6 +1784,9 @@ void intel_ddi_enable_transcoder_func(const struct intel_crtc_state *crtc_state) > I915_WRITE(TRANS_DDI_FUNC_CTL(cpu_transcoder), temp); > } > > +/* Quirk time computed based on 24fps frame time of 41.25ms */ > +#define DDI_DISABLED_QUIRK_TIME 42 > + > void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv, > enum transcoder cpu_transcoder) > { > @@ -1793,6 +1796,11 @@ void intel_ddi_disable_transcoder_func(struct drm_i915_private *dev_priv, > val &= ~(TRANS_DDI_FUNC_ENABLE | TRANS_DDI_PORT_MASK | TRANS_DDI_DP_VC_PAYLOAD_ALLOC); > val |= TRANS_DDI_PORT_NONE; > I915_WRITE(reg, val); > + > + if (dev_priv->quirks & QUIRK_INCREASE_DDI_DISABLED_TIME) { > + msleep(DDI_DISABLED_QUIRK_TIME); > + DRM_DEBUG_KMS("Quirk Increase DDI disabled time\n"); > + } > } > > int intel_ddi_toggle_hdcp_signalling(struct intel_encoder *intel_encoder, > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c > index ed29219..0d07c37 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -14740,6 +14740,17 @@ static void quirk_increase_t12_delay(struct drm_device *dev) > DRM_INFO("Applying T12 delay quirk\n"); > } > > +/* GeminiLake NUC HDMI outputs require additional off time > + * this allows the onboard retimer to correctly sync to signal > + */ > +static void quirk_increase_ddi_disabled_time(struct drm_device *dev) > +{ > + struct drm_i915_private *dev_priv = to_i915(dev); > + > + dev_priv->quirks |= QUIRK_INCREASE_DDI_DISABLED_TIME; > + DRM_INFO("Applying Increase DDI Disabled quirk\n"); > +} > + > struct intel_quirk { > int device; > int subsystem_vendor; > @@ -14826,6 +14837,9 @@ static int intel_dmi_reverse_brightness(const struct dmi_system_id *id) > > /* Toshiba Satellite P50-C-18C */ > { 0x191B, 0x1179, 0xF840, quirk_increase_t12_delay }, > + > + /* GeminiLake NUC */ > + { 0x3185, 0x8086, 0x2072, quirk_increase_ddi_disabled_time }, > }; > > static void intel_init_quirks(struct drm_device *dev) > -- > 1.9.1 > _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
