On 12/11/2023 2:24 PM, Jani Nikula wrote:
On Mon, 11 Dec 2023, Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx> wrote:
Avoid checking for Downstream Facing Port capabilities,
if its not a DP branch device.
Why?
The commit message *always* needs to answer the question why. This
commit message describes what the patch does in English.
Hi Jani,
This was in response to a failure seen sometimes with some DP/eDP panels
while reading DPCDs meant for PCON capabilities.
Perhaps, I Should have started with this, instead of being lazy,
apologies for that.
Since downward facing port capabilities are for DP branch device, I
wondered if some panels would have problems if we read this.
However, I am realizing, that the DPCD read should still work and
perhaps read 0x0 even if the device do not have the capabilities.
Regards,
Ankit
BR,
Jani.
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 3b2482bf683f..bef797b63000 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5502,6 +5502,9 @@ intel_dp_update_dfp(struct intel_dp *intel_dp,
struct drm_i915_private *i915 = dp_to_i915(intel_dp);
struct intel_connector *connector = intel_dp->attached_connector;
+ if (!drm_dp_is_branch(intel_dp->dpcd))
+ return;
+
intel_dp->dfp.max_bpc =
drm_dp_downstream_max_bpc(intel_dp->dpcd,
intel_dp->downstream_ports, drm_edid);
