[Intel-gfx] [PATCH v3 01/19] drm/i915/dp: Sanitize DPCD revision check in intel_dp_get_dsc_sink_cap()

Imre Deak
2023-10-11T17:15:49Z

Check only the eDP or the DP specific DPCD revision depending on the
sink type. Pass the corresponding revision to the function, which allows
getting the DSC caps of a branch device (in an MST topology, which has
its own DPCD and so DPCD revision).

While at it use DP_DPCD_REV_14 instead of open coding it and for clarity
add a separate function to read out the DSC capability on eDP.

v2:
- Use DP_DPCD_REV_14 instead of open coding it. (Stan)
- Check EDP_DCPD_REV/DPCD_REV in a clearer way. (Ville)
v3:
- Fix the read-out for eDP in intel_dp_detect().

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com> (v1)
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (v2)
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
drivers/gpu/drm/i915/display/intel_dp.c | 81 +++++++++++++++++--------
1 file changed, 55 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 4f6835a7578eb..be7de7b5616f1 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -3467,7 +3467,23 @@ bool intel_dp_get_colorimetry_status(struct intel_dp *intel_dp)
return dprx & DP_VSC_SDP_EXT_FOR_COLORIMETRY_SUPPORTED;
}

-static void intel_dp_get_dsc_sink_cap(struct intel_dp *intel_dp)
+static void intel_dp_read_dsc_dpcd(struct drm_dp_aux *aux,
+ u8 dsc_dpcd[DP_DSC_RECEIVER_CAP_SIZE])
+{
+ if (drm_dp_dpcd_read(aux, DP_DSC_SUPPORT, dsc_dpcd,
+ DP_DSC_RECEIVER_CAP_SIZE) < 0) {
+ drm_err(aux->drm_dev,
+ "Failed to read DPCD register 0x%x\n",
+ DP_DSC_SUPPORT);
+ return;
+ }
+
+ drm_dbg_kms(aux->drm_dev, "DSC DPCD: %*ph\n",
+ DP_DSC_RECEIVER_CAP_SIZE,
+ dsc_dpcd);
+}
+
+static void intel_dp_get_dsc_sink_cap(u8 dpcd_rev, struct intel_dp *intel_dp)
{
struct drm_i915_private *i915 = dp_to_i915(intel_dp);

@@ -3480,30 +3496,27 @@ static void intel_dp_get_dsc_sink_cap(struct intel_dp *intel_dp)
/* Clear fec_capable to avoid using stale values */
intel_dp->fec_capable = 0;

- /* Cache the DSC DPCD if eDP or DP rev >= 1.4 */
- if (intel_dp->dpcd[DP_DPCD_REV] >= 0x14 ||
- intel_dp->edp_dpcd[0] >= DP_EDP_14) {
- if (drm_dp_dpcd_read(&intel_dp->aux, DP_DSC_SUPPORT,
- intel_dp->dsc_dpcd,
- sizeof(intel_dp->dsc_dpcd)) < 0)
- drm_err(&i915->drm,
- "Failed to read DPCD register 0x%x\n",
- DP_DSC_SUPPORT);
+ if (dpcd_rev < DP_DPCD_REV_14)
+ return;

- drm_dbg_kms(&i915->drm, "DSC DPCD: %*ph\n",
- (int)sizeof(intel_dp->dsc_dpcd),
- intel_dp->dsc_dpcd);
+ intel_dp_read_dsc_dpcd(&intel_dp->aux, intel_dp->dsc_dpcd);

- /* FEC is supported only on DP 1.4 */
- if (!intel_dp_is_edp(intel_dp) &&
- drm_dp_dpcd_readb(&intel_dp->aux, DP_FEC_CAPABILITY,
- &intel_dp->fec_capable) < 0)
- drm_err(&i915->drm,
- "Failed to read FEC DPCD register\n");
-
- drm_dbg_kms(&i915->drm, "FEC CAPABILITY: %x\n",
- intel_dp->fec_capable);
+ if (drm_dp_dpcd_readb(&intel_dp->aux, DP_FEC_CAPABILITY,
+ &intel_dp->fec_capable) < 0) {
+ drm_err(&i915->drm, "Failed to read FEC DPCD register\n");
+ return;
}
+
+ drm_dbg_kms(&i915->drm, "FEC CAPABILITY: %x\n",
+ intel_dp->fec_capable);
+}
+
+static void intel_edp_get_dsc_sink_cap(u8 edp_dpcd_rev, struct intel_dp *intel_dp)
+{
+ if (edp_dpcd_rev < DP_EDP_14)
+ return;
+
+ intel_dp_read_dsc_dpcd(&intel_dp->aux, intel_dp->dsc_dpcd);
}

static void intel_edp_mso_mode_fixup(struct intel_connector *connector,
@@ -3674,7 +3687,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp)

/* Read the eDP DSC DPCD registers */
if (HAS_DSC(dev_priv))
- intel_dp_get_dsc_sink_cap(intel_dp);
+ intel_edp_get_dsc_sink_cap(intel_dp->edp_dpcd[0],
+ intel_dp);

/*
* If needed, program our source OUI so we can make various Intel-specific AUX services
@@ -5338,6 +5352,23 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
false);
}

+static void
+intel_dp_detect_dsc_caps(struct intel_dp *intel_dp)
+{
+ struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+
+ /* Read DP Sink DSC Cap DPCD regs for DP v1.4 */
+ if (!HAS_DSC(i915))
+ return;
+
+ if (intel_dp_is_edp(intel_dp))
+ intel_edp_get_dsc_sink_cap(intel_dp->edp_dpcd[0],
+ intel_dp);
+ else
+ intel_dp_get_dsc_sink_cap(intel_dp->dpcd[DP_DPCD_REV],
+ intel_dp);
+}
+
static int
intel_dp_detect(struct drm_connector *connector,
struct drm_modeset_acquire_ctx *ctx,
@@ -5382,9 +5413,7 @@ intel_dp_detect(struct drm_connector *connector,
goto out;
}

- /* Read DP Sink DSC Cap DPCD regs for DP v1.4 */
- if (HAS_DSC(dev_priv))
- intel_dp_get_dsc_sink_cap(intel_dp);
+ intel_dp_detect_dsc_caps(intel_dp);

intel_dp_configure_mst(intel_dp);

--
2.39.2