linux-kernel - Re: [PATCH v2] drm_bridge: register content protect property

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Date:   Wed, 19 Oct 2022 14:25:19 +0800
From:   Hsin-Yi Wang <hsinyi@...omium.org>
To:     Sean Paul <seanpaul@...omium.org>
Cc:     Douglas Anderson <dianders@...omium.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] drm_bridge: register content protect property

On Wed, Oct 19, 2022 at 2:26 AM Sean Paul <seanpaul@...omium.org> wrote:
>
> On Mon, Oct 17, 2022 at 9:49 AM Hsin-Yi Wang <hsinyi@...omium.org> wrote:
> >
> > On Wed, Oct 12, 2022 at 12:20 PM Hsin-Yi Wang <hsinyi@...omium.org> wrote:
> > >
> > > Some bridges are able to update HDCP status from userspace request if
> > > they support HDCP.
> > >
> > > HDCP property is the same as other connector properties that need to be
> > > created after the connecter is initialized and before the connector is
> > > registered.
> > >
> > anx7625 is a user for this.
>
> I feel like we should not unconditionally attach this property for
> bridges, this should be done in the driver which supports it IMO.
>
I sent another version to register the property in drm driver:
https://lore.kernel.org/lkml/20221019061936.3599965-1-hsinyi@chromium.org/T/#u

Ideally it should be registered by the bridge driver. But some bridge
drivers have already changed to DRM_BRIDGE_ATTACH_NO_CONNECTOR, so
they can't get a connector during the attach stage (or any time before
the connector is registered). Is it acceptable that drm driver help
register the property if CONFIG_DRM_DISPLAY_HDCP_HELPER is defined?

Thanks

> Sean
>
> >
> >
> > > Signed-off-by: Hsin-Yi Wang <hsinyi@...omium.org>
> > > Reported-by: kernel test robot <lkp@...el.com>
> > > ---
> > > v2: Fix compile error when config is not set.
> > > ---
> > >  drivers/gpu/drm/drm_bridge_connector.c | 3 +++
> > >  include/drm/display/drm_hdcp_helper.h  | 8 ++++++++
> > >  2 files changed, 11 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
> > > index 1c7d936523df5..a3b9ef8dc3f0b 100644
> > > --- a/drivers/gpu/drm/drm_bridge_connector.c
> > > +++ b/drivers/gpu/drm/drm_bridge_connector.c
> > > @@ -7,6 +7,7 @@
> > >  #include <linux/module.h>
> > >  #include <linux/slab.h>
> > >
> > > +#include <drm/display/drm_hdcp_helper.h>
> > >  #include <drm/drm_atomic_state_helper.h>
> > >  #include <drm/drm_bridge.h>
> > >  #include <drm/drm_bridge_connector.h>
> > > @@ -398,6 +399,8 @@ struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
> > >         if (panel_bridge)
> > >                 drm_panel_bridge_set_orientation(connector, panel_bridge);
> > >
> > > +       drm_connector_attach_content_protection_property(connector, true);
> > > +
> > >         return connector;
> > >  }
> > >  EXPORT_SYMBOL_GPL(drm_bridge_connector_init);
> > > diff --git a/include/drm/display/drm_hdcp_helper.h b/include/drm/display/drm_hdcp_helper.h
> > > index 8aaf87bf27351..c65d9f06a2532 100644
> > > --- a/include/drm/display/drm_hdcp_helper.h
> > > +++ b/include/drm/display/drm_hdcp_helper.h
> > > @@ -15,8 +15,16 @@ struct drm_device;
> > >  struct drm_connector;
> > >
> > >  int drm_hdcp_check_ksvs_revoked(struct drm_device *dev, u8 *ksvs, u32 ksv_count);
> > > +#if defined(CONFIG_DRM_DISPLAY_HDCP_HELPER)
> > >  int drm_connector_attach_content_protection_property(struct drm_connector *connector,
> > >                                                      bool hdcp_content_type);
> > > +#else
> > > +static inline int drm_connector_attach_content_protection_property(struct drm_connector *connector,
> > > +                                                                  bool hdcp_content_type)
> > > +{
> > > +       return 0;
> > > +}
> > > +#endif
> > >  void drm_hdcp_update_content_protection(struct drm_connector *connector, u64 val);
> > >
> > >  #endif
> > > --
> > > 2.38.0.rc1.362.ged0d419d3c-goog
> > >