Re: [Intel-gfx] [PATCH 3/4] drm/i915: Fix platform default aux ch for skl

[Nautiyal, Ankit K]

On 2/17/2023 4:43 AM, Ville Syrjala wrote:
From: Ville Syrjälä <ville.syrj...@linux.intel.com>

SKL/derivatives have DDI E but no AUX E, so we need to pick
another aux ch as the platform default. DDI E is more or less
the other half of DDI A, so we pick AUX A.

In all other cases we should have a corresponding aux ch for
each DDI.

Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
  drivers/gpu/drm/i915/display/intel_dp_aux.c | 14 ++++++++++++--
  1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c 
b/drivers/gpu/drm/i915/display/intel_dp_aux.c
index 57eb3ff187fa..96967e21c94c 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
@@ -739,10 +739,20 @@ void intel_dp_aux_init(struct intel_dp *intel_dp)
        cpu_latency_qos_add_request(&intel_dp->pm_qos, PM_QOS_DEFAULT_VALUE);
  }
  
+static enum aux_ch default_aux_ch(struct intel_encoder *encoder)
+{
+       struct drm_i915_private *i915 = to_i915(encoder->base.dev);
+
+       /* SKL has DDI E but no AUX E */
+       if (DISPLAY_VER(i915) == 9 && encoder->port == PORT_E)
+               return AUX_CH_A;
+

I guess we might need to fix intel_dp_aux_init also. Wont we have 
dig_port->aux_ch and intel_dp->aux_ch pointing to different things?

For example for SKL and DDI E, intel_dp->aux.name will be derived from 
dig_port->aux_ch i.e. AUX_CH_A but intel_dp->aux_ctl/data reg will still 
point to DP_AUX_CH_CTL/DATA_E.

Am I missing something?

Regards,

Ankit


+       return (enum aux_ch)encoder->port;
+}
+
  enum aux_ch intel_dp_aux_ch(struct intel_encoder *encoder)
  {
        struct drm_i915_private *i915 = to_i915(encoder->base.dev);
-       enum port port = encoder->port;
        enum aux_ch aux_ch;
  
  	aux_ch = intel_bios_dp_aux_ch(encoder->devdata);
@@ -753,7 +763,7 @@ enum aux_ch intel_dp_aux_ch(struct intel_encoder *encoder)
                return aux_ch;
        }
  
-	aux_ch = (enum aux_ch)port;
+       aux_ch = default_aux_ch(encoder);
  
  	drm_dbg_kms(&i915->drm,
                    "[ENCODER:%d:%s] using AUX %c (platform default)\n",