drm/i915/psr: Check if resolution is supported by default SU granularity

Selective updates have a default granularity requirements as stated
by eDP spec(PSR2 SELECTIVE UPDATE X GRANULARITY CAPABILITY register
definition), so check if HW can match those requirements before
enabling PSR2.

v3:
- Changes in the comments and commit message(Dhinakaran)
- Printing the hdisplay that do not match with default granularity

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181204003403.23361-8-jose.souza@intel.com

diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 11b038b..298c314 100644 (file)
--- a/drivers/gpu/drm/i915/intel_psr.c
+++ b/drivers/gpu/drm/i915/intel_psr.c
@@ -536,6 +536,17 @@ static bool intel_psr2_config_valid(struct intel_dp *intel_dp,
                return false;
        }
 
+       /*
+        * HW sends SU blocks of size four scan lines, which means the starting
+        * X coordinate and Y granularity requirements will always be met. We
+        * only need to validate the SU block width is a multiple of 4.
+        */
+       if (crtc_hdisplay % 4) {
+               DRM_DEBUG_KMS("PSR2 not enabled, hdisplay(%d) not multiple of 4\n",
+                             crtc_hdisplay);
+               return false;
+       }
+
        return true;
 }