Re: [PATCH] drm/i915: Fix MST oops due to MSA changes

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Oct 16, 2019 at 02:59:45PM +0000, Shankar, Uma wrote:
> 
> 
> >-----Original Message-----
> >From: Ville Syrjala <ville.syrjala@linux.intel.com>
> >Sent: Wednesday, October 16, 2019 12:36 AM
> >To: intel-gfx@lists.freedesktop.org
> >Cc: Mun, Gwan-gyeong <gwan-gyeong.mun@intel.com>; Shankar, Uma
> ><uma.shankar@intel.com>
> >Subject: [PATCH] drm/i915: Fix MST oops due to MSA changes
> >
> >From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> >The MSA MISC computation now depends on the connector state, and we do it from
> >the DDI .pre_enable() hook. All that is fine for DP SST but with MST we don't actually
> >pass the connector state to the dig port's .pre_enable() hook which leads to an oops.
> >
> >Need to think more how to solve this in a cleaner fashion, but for now let's just add a
> >NULL check to stop the oopsing.
> 
> Looks good to me. We will have to handle colorspaces for MST properly.

Yeah, in fact just realized that this is a transcoder register so we're
no longer configuring MSA MISC for anything but the first MST stream.
The other streams will leave TRANS_MSA_MISC untouched. So I guess we
need to move this into the MST code proper, and if it needs to be left
in ddi_pre_enable() for SST we probably want to exclude it getting
programming there for MST there. Any volunteers?

Pushed. Thanks for the reviews.

> But that can be
> done later. Thanks for identifying and fixing this.
> Reviewed-by: Uma Shankar <uma.shankar@intel.com>
> 
> >Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> >Cc: Uma Shankar <uma.shankar@intel.com>
> >Fixes: 0c06fa156006 ("drm/i915/dp: Add support of BT.2020 Colorimetry to DP MSA")
> >Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >---
> > drivers/gpu/drm/i915/display/intel_ddi.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> >diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
> >b/drivers/gpu/drm/i915/display/intel_ddi.c
> >index 80f8e2698be0..4c81449ec144 100644
> >--- a/drivers/gpu/drm/i915/display/intel_ddi.c
> >+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> >@@ -1794,8 +1794,10 @@ void intel_ddi_set_dp_msa(const struct intel_crtc_state
> >*crtc_state,
> > 	 * of Color Encoding Format and Content Color Gamut] while sending
> > 	 * YCBCR 420, HDR BT.2020 signals we should program MSA MISC1 fields
> > 	 * which indicate VSC SDP for the Pixel Encoding/Colorimetry Format.
> >+	 *
> >+	 * FIXME MST doesn't pass in the conn_state
> > 	 */
> >-	if (intel_dp_needs_vsc_sdp(crtc_state, conn_state))
> >+	if (conn_state && intel_dp_needs_vsc_sdp(crtc_state, conn_state))
> > 		temp |= DP_MSA_MISC_COLOR_VSC_SDP;
> >
> > 	I915_WRITE(TRANS_MSA_MISC(cpu_transcoder), temp);
> >--
> >2.21.0
> 

-- 
Ville Syrjälä
Intel
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