Re: [PATCH v6 02/10] drm/hdcp: Avoid changing crtc state in hdcp atomic check

Dmitry Baryshkov
2023-01-19T11:46:10Z

On 18/01/2023 21:30, Mark Yacoub wrote:
> From: Sean Paul <seanpaul@chromium.org>
>
> Instead of forcing a modeset in the hdcp atomic check, simply return
> true if the content protection value is changing and let the driver
> decide whether a modeset is required or not.

I don't think this is a good idea. All foo_atomic_check functions return
an error code (or 0 if atomic check passes). Making
drm_hpcp_atomic_check return bool is against that custom and is a clear
way to make one forget to notice that. Please rename function to remove
possible confusion.

>
> Acked-by: Jani Nikula <jani.nikula@intel.com>
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> Signed-off-by: Mark Yacoub <markyacoub@chromium.org>
> Link: https://patchwork.freedesktop.org/patch/msgid/20210913175747.47456-3-sean@poorly.run #v1
> Link: https://patchwork.freedesktop.org/patch/msgid/20210915203834.1439-3-sean@poorly.run #v2
> Link: https://patchwork.freedesktop.org/patch/msgid/20211001151145.55916-3-sean@poorly.run #v3
> Link: https://patchwork.freedesktop.org/patch/msgid/20211105030434.2828845-3-sean@poorly.run #v4
> Link: https://patchwork.freedesktop.org/patch/msgid/20220411204741.1074308-3-sean@poorly.run #v5
>
> Changes in v2:
> -None
> Changes in v3:
> -None
> Changes in v4:
> -None
> Changes in v5:
> -None
> Changes in V6:
> -Rebase: modifications in drm_hdcp_helper.c instead of drm_hdcp.c
>
> ---
> drivers/gpu/drm/display/drm_hdcp_helper.c | 33 +++++++++++++++------
> drivers/gpu/drm/i915/display/intel_atomic.c | 6 ++--
> include/drm/display/drm_hdcp_helper.h | 2 +-
> 3 files changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/display/drm_hdcp_helper.c b/drivers/gpu/drm/display/drm_hdcp_helper.c
> index 7d910523b05f..a3896b0904b5 100644
> --- a/drivers/gpu/drm/display/drm_hdcp_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdcp_helper.c
> @@ -428,11 +428,14 @@ EXPORT_SYMBOL(drm_hdcp_update_content_protection);
> * @connector: drm_connector on which content protection state needs an update
> *
> * This function can be used by display drivers to perform an atomic check on the
> - * hdcp state elements. If hdcp state has changed, this function will set
> - * mode_changed on the crtc driving the connector so it can update its hardware
> - * to match the hdcp state.
> + * hdcp state elements. If hdcp state has changed in a manner which requires the
> + * driver to enable or disable content protection, this function will return
> + * true.
> + *
> + * Returns:
> + * true if the driver must enable/disable hdcp, false otherwise
> */
> -void drm_hdcp_atomic_check(struct drm_connector *connector,
> +bool drm_hdcp_atomic_check(struct drm_connector *connector,
> struct drm_atomic_state *state)
> {
> struct drm_connector_state *new_conn_state, *old_conn_state;
> @@ -450,10 +453,12 @@ void drm_hdcp_atomic_check(struct drm_connector *connector,
> * If the connector is being disabled with CP enabled, mark it
> * desired so it's re-enabled when the connector is brought back
> */
> - if (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED)
> + if (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED) {
> new_conn_state->content_protection =
> DRM_MODE_CONTENT_PROTECTION_DESIRED;
> - return;
> + return true;
> + }
> + return false;
> }
>
> new_crtc_state =
> @@ -465,9 +470,19 @@ void drm_hdcp_atomic_check(struct drm_connector *connector,
> */
> if (drm_atomic_crtc_needs_modeset(new_crtc_state) &&
> (old_hdcp == DRM_MODE_CONTENT_PROTECTION_ENABLED &&
> - new_hdcp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED))
> + new_hdcp != DRM_MODE_CONTENT_PROTECTION_UNDESIRED)) {
> new_conn_state->content_protection =
> DRM_MODE_CONTENT_PROTECTION_DESIRED;
> + return true;
> + }
> +
> + /*
> + * Coming back from disable or changing CRTC with DESIRED state requires
> + * that the driver try CP enable.
> + */
> + if (new_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED &&
> + new_conn_state->crtc != old_conn_state->crtc)
> + return true;
>
> /*
> * Nothing to do if content type is unchanged and one of:
> @@ -482,9 +497,9 @@ void drm_hdcp_atomic_check(struct drm_connector *connector,
> new_hdcp == DRM_MODE_CONTENT_PROTECTION_DESIRED)) {
> if (old_conn_state->hdcp_content_type ==
> new_conn_state->hdcp_content_type)
> - return;
> + return false;
> }
>
> - new_crtc_state->mode_changed = true;
> + return true;
> }
> EXPORT_SYMBOL(drm_hdcp_atomic_check);
> diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
> index 8a473199c4bf..a2067cbae2d5 100644
> --- a/drivers/gpu/drm/i915/display/intel_atomic.c
> +++ b/drivers/gpu/drm/i915/display/intel_atomic.c
> @@ -123,8 +123,6 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
> to_intel_digital_connector_state(old_state);
> struct drm_crtc_state *crtc_state;
>
> - drm_hdcp_atomic_check(conn, state);
> -
> if (!new_state->crtc)
> return 0;
>
> @@ -140,8 +138,8 @@ int intel_digital_connector_atomic_check(struct drm_connector *conn,
> new_conn_state->base.picture_aspect_ratio != old_conn_state->base.picture_aspect_ratio ||
> new_conn_state->base.content_type != old_conn_state->base.content_type ||
> new_conn_state->base.scaling_mode != old_conn_state->base.scaling_mode ||
> - new_conn_state->base.privacy_screen_sw_state != old_conn_state->base.privacy_screen_sw_state ||
> - !drm_connector_atomic_hdr_metadata_equal(old_state, new_state))
> + !drm_connector_atomic_hdr_metadata_equal(old_state, new_state) ||
> + drm_hdcp_atomic_check(conn, state))
> crtc_state->mode_changed = true;
>
> return 0;
> diff --git a/include/drm/display/drm_hdcp_helper.h b/include/drm/display/drm_hdcp_helper.h
> index dd02b2e72a50..cb2cc5002f65 100644
> --- a/include/drm/display/drm_hdcp_helper.h
> +++ b/include/drm/display/drm_hdcp_helper.h
> @@ -19,7 +19,7 @@ int drm_hdcp_check_ksvs_revoked(struct drm_device *dev, u8 *ksvs, u32 ksv_count)
> int drm_connector_attach_content_protection_property(struct drm_connector *connector,
> bool hdcp_content_type);
> void drm_hdcp_update_content_protection(struct drm_connector *connector, u64 val);
> -void drm_hdcp_atomic_check(struct drm_connector *connector,
> +bool drm_hdcp_atomic_check(struct drm_connector *connector,
> struct drm_atomic_state *state);
>
> #endif

--
With best wishes
Dmitry