On 2020-05-20 at 15:47:44 -0400, Sean Paul wrote:
> From: Sean Paul <seanp...@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.
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
>
> Signed-off-by: Sean Paul <seanp...@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;
> --
> Sean Paul, Software Engineer, Google / Chromium OS
>
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