On 2020-05-21 at 10:27:21 +0530, Ramalingam C wrote:
> 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.
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.
> 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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