[Intel-gfx] [PATCH v3 8/9] drm/i915/psr: Check if resolution is supported by default SU granularity

[José Roberto de Souza]

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.

v2:
- Changes in the comments and commit message(Dhinakaran)
- Printing the hdisplay that do not match with default granularity

Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
---
 drivers/gpu/drm/i915/intel_psr.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_psr.c b/drivers/gpu/drm/i915/intel_psr.c
index 40a81e084a96..0aa909018c53 100644
--- 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;
 }
 
-- 
2.19.2