From: Sean Paul seanpaul@chromium.org
If userspace sets the CP property to DESIRED while it's already ENABLED, the driver will try to re-enable HDCP. On some displays, this will result in R0' mismatches. I'm guessing this is because the display is still sending back Ri instead of re-authenticating.
At any rate, we can fix this inefficiency easily enough by just nooping the DESIRED property set if HDCP is already ENABLED.
Signed-off-by: Sean Paul seanpaul@chromium.org ---
I suspect this is the actual root cause I was chasing with "drm/i915/hdcp: Add additional R0' wait". I was able to reproduce the R0` messages by marking HDCP desired while it was already enabled. This _should_ work, but it seems like some displays handle it more graciously than others.
drivers/gpu/drm/i915/display/intel_hdcp.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c index 2cbc4619b4ce..f770fe0c5595 100644 --- a/drivers/gpu/drm/i915/display/intel_hdcp.c +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c @@ -2156,12 +2156,16 @@ void intel_hdcp_atomic_check(struct drm_connector *connector, }
/* - * Nothing to do if the state didn't change, or HDCP was activated since - * the last commit. And also no change in hdcp content type. + * Nothing to do if content type is unchanged and one of: + * - state didn't change + * - HDCP was activated since the last commit + * - attempting to set to desired while already enabled */ if (old_cp == new_cp || (old_cp == DRM_MODE_CONTENT_PROTECTION_DESIRED && - new_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED)) { + new_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED) || + (old_cp == DRM_MODE_CONTENT_PROTECTION_ENABLED && + new_cp == DRM_MODE_CONTENT_PROTECTION_DESIRED)) { if (old_state->hdcp_content_type == new_state->hdcp_content_type) return;
On 2020-05-20 at 15:47:44 -0400, Sean Paul wrote:
Sean,
This will skip the hdcp enable.
But at present too we will be getting below WARN_ON from intel_hdcp_enable, to indicate userspace is going wrong with request. drm_WARN_ON(&dev_priv->drm, hdcp->value == DRM_MODE_CONTENT_PROTECTION_ENABLED);
And if we need to filter this out, could we validate the incoming hdcp request at drm_atomic_connector_set_property() itself? No point in going into the atomic commit without a valid request. something like
diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c index a1e5e262bae2..d98b2eeae78d 100644 --- a/drivers/gpu/drm/drm_atomic_uapi.c +++ b/drivers/gpu/drm/drm_atomic_uapi.c @@ -746,6 +746,12 @@ static int drm_atomic_connector_set_property(struct drm_connector *connector, DRM_DEBUG_KMS("only drivers can set CP Enabled\n"); return -EINVAL; } + if (config->content_protection_property == + DRM_MODE_CONTENT_PROTECTION_ENABLED && + val == DRM_MODE_CONTENT_PROTECTION_DESIRED) { + DRM_DEBUG_KMS("Redundant req for content protection\n"); + return -EINVAL; + } state->content_protection = val; } else if (property == config->hdcp_content_type_property) { state->hdcp_content_type = val;
-Ram
On 2020-05-21 at 10:27:21 +0530, Ramalingam C wrote:
AFAIU may below patch also solves above issue implicitly. https://patchwork.freedesktop.org/patch/365758/?series=72251&rev=4 Besides that +1 for below Ram comment, it would be better if such type of duplicate enable request should filter by drm_atomic_connector_set_property(). Thanks, Anshuman Gupta.
On Thu, May 21, 2020 at 5:36 AM Anshuman Gupta anshuman.gupta@intel.com wrote:
Thanks Anshuman, I didn't see that patch. Indeed that seems like it accomplishes the same thing.
Let's drop this.
Sean
dri-devel@lists.freedesktop.org
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Anshuman Gupta -
Ramalingam C -
Sean Paul