Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status at atomic_enable()

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On Mon, Dec 16, 2024 at 08:33:23AM +0000, Xin Ji wrote:
> > -----Original Message-----
> > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Sent: Friday, December 13, 2024 9:17 PM
> > To: Xin Ji <xji@xxxxxxxxxxxxxxxx>
> > Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>; Neil Armstrong
> > <neil.armstrong@xxxxxxxxxx>; Robert Foss <rfoss@xxxxxxxxxx>; Laurent Pinchart
> > <Laurent.pinchart@xxxxxxxxxxxxxxxx>; Jonas Karlman <jonas@xxxxxxxxx>;
> > Jernej Skrabec <jernej.skrabec@xxxxxxxxx>; Maarten Lankhorst
> > <maarten.lankhorst@xxxxxxxxxxxxxxx>; Maxime Ripard <mripard@xxxxxxxxxx>;
> > Thomas Zimmermann <tzimmermann@xxxxxxx>; David Airlie
> > <airlied@xxxxxxxxx>; Simona Vetter <simona@xxxxxxxx>; Bernie Liang
> > <bliang@xxxxxxxxxxxxxxxx>; Qilin Wen <qwen@xxxxxxxxxxxxxxxx>;
> > treapking@xxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-
> > kernel@xxxxxxxxxxxxxxx
> > Subject: Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status at
> > atomic_enable()
> > 
> > CAUTION: This email originated from outside of the organization. Please do not
> > click links or open attachments unless you recognize the sender, and know the
> > content is safe.
> > 
> > 
> > On Fri, 13 Dec 2024 at 13:00, Xin Ji <xji@xxxxxxxxxxxxxxxx> wrote:
> > >
> > > Hi Dmitry, sorry, I didn't clear describe the reason.
> > 
> > Please. Do not top-post. Please paste your answer under the question, not
> > somewhere at the top of the email. This allows us to have a more constructive
> > dialog. Additional bonus if you can fix your email client to insert sensible quoting
> > information instead of dumping the headers of the original email.
> Hi Dmitry, OK, sorry about it. Currently, we have problem to fetch email from
> Microsoft on Ubuntu. I'll try to fix it later.
> > 
> > >
> > > Anx7625 implement DSI to DP convert behind USB Type-C port, when user
> > > plug into USB Type-C Dongle with DP monitor, the user space will
> > > enable HDCP feature, then kernel do HDCP and output display and set
> > > HDCP content to ENABLE, but the issue happened if user manually change the
> > monitor's resolution later.
> > >
> > > Each time user change the resolution, kernel will call bridge
> > > interface .atomic_disable() and .atomic_enable(), the old driver will
> > > keep HDCP state to ENABLE, this is a BUG, when user change the
> > > resolution, kernel must change HDCP content too (mustn't keep to
> > > ENABLE),
> > 
> > Why? Could you please point me to the corresponding documentation or a code
> > path in the other driver? Preferably i915, AMD or Nouveau.
> As https://elixir.bootlin.com/linux/v6.12.5/source/drivers/gpu/drm/drm_connector.c#L1423: 
>         - ENABLED -> DESIRED (termination of authentication)
> As there is no other interface to tell anx7625 bridge driver, so the I think best place to handle
> ENABLE -> DESIRED in .atomic_disable().

I was looking for something like cdns_mhdp_connector_atomic_check(),
which switches to UNDESIRED if there is no new CRTC. Likewise i915
driver performs this in intel_hdcp_atomic_check() if there is a need for
modeset.

For the "termination of authentication" case see
cdns_mhdp_hdcp_check_link(), which detects if the HDCP got disabled by
HW and then updates the status accordingly.

> 
> > 
> > > as DRM doc said, kernel cannot change from ENABLE to UNDESIRE, so next
> > > patch, I'll change it to DESIRE in .atomic_disable().

This e.g. will result in HDCP being restarted for all modesets. Is this
an expected behaviour?

> > >
> > > Thanks!
> > > Xin
> > >
> > > > -----Original Message-----
> > > > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > > > Sent: Friday, December 13, 2024 6:47 PM
> > > > To: Xin Ji <xji@xxxxxxxxxxxxxxxx>
> > > > Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>; Neil Armstrong
> > > > <neil.armstrong@xxxxxxxxxx>; Robert Foss <rfoss@xxxxxxxxxx>; Laurent
> > > > Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>; Jonas Karlman
> > > > <jonas@xxxxxxxxx>; Jernej Skrabec <jernej.skrabec@xxxxxxxxx>;
> > > > Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>; Maxime Ripard
> > > > <mripard@xxxxxxxxxx>; Thomas Zimmermann <tzimmermann@xxxxxxx>;
> > David
> > > > Airlie <airlied@xxxxxxxxx>; Simona Vetter <simona@xxxxxxxx>; Bernie
> > > > Liang <bliang@xxxxxxxxxxxxxxxx>; Qilin Wen <qwen@xxxxxxxxxxxxxxxx>;
> > > > treapking@xxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux-
> > > > kernel@xxxxxxxxxxxxxxx
> > > > Subject: Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status at
> > > > atomic_enable()
> > > >
> > > > CAUTION: This email originated from outside of the organization.
> > > > Please do not click links or open attachments unless you recognize
> > > > the sender, and know the content is safe.
> > > >
> > > >
> > > > On Fri, Dec 13, 2024 at 10:06:36AM +0000, Xin Ji wrote:
> > > > > Hi Dmitry, thanks for the review, I made some changes which change
> > > > > ENABLE to DESIRE in .atomic_disable(), I'll upstream it after testing. Thanks!
> > > >
> > > > - Please don't top-post.
> > > >
> > > > - You still didn't explain, why do you want to do this change of HDCP
> > > >   status. Could you please provide an explanation before sending the
> > > >   next iteration?
> > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > > > > > Sent: Thursday, December 12, 2024 5:18 PM
> > > > > > To: Xin Ji <xji@xxxxxxxxxxxxxxxx>
> > > > > > Cc: Andrzej Hajda <andrzej.hajda@xxxxxxxxx>; Neil Armstrong
> > > > > > <neil.armstrong@xxxxxxxxxx>; Robert Foss <rfoss@xxxxxxxxxx>;
> > > > > > Laurent Pinchart <Laurent.pinchart@xxxxxxxxxxxxxxxx>; Jonas
> > > > > > Karlman <jonas@xxxxxxxxx>; Jernej Skrabec
> > > > > > <jernej.skrabec@xxxxxxxxx>; Maarten Lankhorst
> > > > > > <maarten.lankhorst@xxxxxxxxxxxxxxx>; Maxime Ripard
> > > > > > <mripard@xxxxxxxxxx>; Thomas Zimmermann <tzimmermann@xxxxxxx>;
> > > > David
> > > > > > Airlie <airlied@xxxxxxxxx>; Simona Vetter <simona@xxxxxxxx>;
> > > > > > Bernie Liang <bliang@xxxxxxxxxxxxxxxx>; Qilin Wen
> > > > > > <qwen@xxxxxxxxxxxxxxxx>; treapking@xxxxxxxxxx;
> > > > > > dri-devel@xxxxxxxxxxxxxxxxxxxxx; linux- kernel@xxxxxxxxxxxxxxx
> > > > > > Subject: Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status
> > > > > > at
> > > > > > atomic_enable()
> > > > > >
> > > > > > CAUTION: This email originated from outside of the organization.
> > > > > > Please do not click links or open attachments unless you
> > > > > > recognize the sender, and know the content is safe.
> > > > > >
> > > > > >
> > > > > > On Thu, Dec 12, 2024 at 01:51:10PM +0800, Xin Ji wrote:
> > > > > > > When user enabled HDCP feature, userspace will set HDCP
> > > > > > > content to DRM_MODE_CONTENT_PROTECTION_DESIRED. Next,
> > anx7625
> > > > > > > will
> > > > update
> > > > > > HDCP
> > > > > > > content to DRM_MODE_CONTENT_PROTECTION_ENABLED if down
> > > > stream
> > > > > > support
> > > > > > > HDCP feature.
> > > > > > >
> > > > > > > However once HDCP content turn to
> > > > > > DRM_MODE_CONTENT_PROTECTION_ENABLED
> > > > > > > userspace will not update the HDCP content to
> > > > > > > DRM_MODE_CONTENT_PROTECTION_UNDESIRED until monitor
> > > > disconnect.
> > > > > >
> > > > > > It seems you've ingored a part of the previous review comment.
> > > > > > It's the userspace who triggers the ENABLED -> UNDESIRED
> > > > > > transition, not the kernel side. The change to move HDCP
> > > > > > handling to atomic_enable() looks fine, the change to disable
> > > > > > HDCP is not (unless I misunderstand
> > > > something).
> > > > > >
> > > > > > >
> > > > > > > So, anx7625 driver move hdcp content value checking from
> > > > > > > bridge interface .atomic_check() to .atomic_enable(), then
> > > > > > > update hdcp content according from currently HDCP status. And
> > > > > > > also disabled HDCP in bridge interface .atomic_disable().
> > > > > > >
> > > > > > > Signed-off-by: Xin Ji <xji@xxxxxxxxxxxxxxxx>
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/bridge/analogix/anx7625.c | 74
> > > > > > > ++++++++++++++---------
> > > > > > >  1 file changed, 46 insertions(+), 28 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > > > > > b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > > > > > index a2675b121fe4..f96ce5665e8d 100644
> > > > > > > --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > > > > > +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> > > > > > > @@ -861,6 +861,22 @@ static int anx7625_hdcp_disable(struct
> > > > > > > anx7625_data
> > > > > > *ctx)
> > > > > > >                                TX_HDCP_CTRL0, ~HARD_AUTH_EN &
> > > > > > > 0xFF); }
> > > > > > >
> > > > > > > +static void anx7625_hdcp_disable_and_update_cp(struct
> > > > > > > +anx7625_data
> > > > > > > +*ctx) {
> > > > > > > +     struct device *dev = ctx->dev;
> > > > > > > +
> > > > > > > +     if (!ctx->connector)
> > > > > > > +             return;
> > > > > > > +
> > > > > > > +     anx7625_hdcp_disable(ctx);
> > > > > > > +
> > > > > > > +     ctx->hdcp_cp = DRM_MODE_CONTENT_PROTECTION_UNDESIRED;
> > > > > > > +     drm_hdcp_update_content_protection(ctx->connector,
> > > > > > > +                                        ctx->hdcp_cp);
> > > > > > > +
> > > > > > > +     dev_dbg(dev, "update CP to UNDESIRE\n"); }
> > > > > > > +
> > > > > > >  static int anx7625_hdcp_enable(struct anx7625_data *ctx)  {
> > > > > > >       u8 bcap;
> > > > > > > @@ -2149,34 +2165,6 @@ static int
> > > > > > > anx7625_connector_atomic_check(struct
> > > > > > anx7625_data *ctx,
> > > > > > >       if (cp == ctx->hdcp_cp)
> > > > > > >               return 0;
> > > > > > >
> > > > > > > -     if (cp == DRM_MODE_CONTENT_PROTECTION_DESIRED) {
> > > > > > > -             if (ctx->dp_en) {
> > > > > > > -                     dev_dbg(dev, "enable HDCP\n");
> > > > > > > -                     anx7625_hdcp_enable(ctx);
> > > > > > > -
> > > > > > > -                     queue_delayed_work(ctx->hdcp_workqueue,
> > > > > > > -                                        &ctx->hdcp_work,
> > > > > > > -                                        msecs_to_jiffies(2000));
> > > > > > > -             }
> > > > > > > -     }
> > > > > > > -
> > > > > > > -     if (cp == DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
> > > > > > > -             if (ctx->hdcp_cp !=
> > > > DRM_MODE_CONTENT_PROTECTION_ENABLED) {
> > > > > > > -                     dev_err(dev, "current CP is not ENABLED\n");
> > > > > > > -                     return -EINVAL;
> > > > > > > -             }
> > > > > > > -             anx7625_hdcp_disable(ctx);
> > > > > > > -             ctx->hdcp_cp =
> > DRM_MODE_CONTENT_PROTECTION_UNDESIRED;
> > > > > > > -             drm_hdcp_update_content_protection(ctx->connector,
> > > > > > > -                                                ctx->hdcp_cp);
> > > > > > > -             dev_dbg(dev, "update CP to UNDESIRE\n");
> > > > > > > -     }
> > > > > > > -
> > > > > > > -     if (cp == DRM_MODE_CONTENT_PROTECTION_ENABLED) {
> > > > > > > -             dev_err(dev, "Userspace illegal set to PROTECTION ENABLE\n");
> > > > > > > -             return -EINVAL;
> > > > > > > -     }
> > > > > > > -
> > > > > > >       return 0;
> > > > > > >  }
> > > > > > >
> > > > > > > @@ -2425,6 +2413,8 @@ static void
> > > > > > > anx7625_bridge_atomic_enable(struct
> > > > > > drm_bridge *bridge,
> > > > > > >       struct anx7625_data *ctx = bridge_to_anx7625(bridge);
> > > > > > >       struct device *dev = ctx->dev;
> > > > > > >       struct drm_connector *connector;
> > > > > > > +     struct drm_connector_state *conn_state;
> > > > > > > +     int cp;
> > > > > > >
> > > > > > >       dev_dbg(dev, "drm atomic enable\n");
> > > > > > >
> > > > > > > @@ -2439,6 +2429,32 @@ static void
> > > > > > > anx7625_bridge_atomic_enable(struct
> > > > > > drm_bridge *bridge,
> > > > > > >       _anx7625_hpd_polling(ctx, 5000 * 100);
> > > > > > >
> > > > > > >       anx7625_dp_start(ctx);
> > > > > > > +
> > > > > > > +     conn_state =
> > > > > > > + drm_atomic_get_new_connector_state(state->base.state,
> > > > > > > + connector);
> > > > > > > +
> > > > > > > +     if (WARN_ON(!conn_state))
> > > > > > > +             return;
> > > > > > > +
> > > > > > > +     cp = conn_state->content_protection;
> > > > > > > +     if (cp == DRM_MODE_CONTENT_PROTECTION_DESIRED) {
> > > > > > > +             if (ctx->dp_en) {
> > > > > > > +                     dev_dbg(dev, "enable HDCP\n");
> > > > > > > +                     anx7625_hdcp_enable(ctx);
> > > > > > > +
> > > > > > > +                     queue_delayed_work(ctx->hdcp_workqueue,
> > > > > > > +                                        &ctx->hdcp_work,
> > > > > > > +                                        msecs_to_jiffies(2000));
> > > > > > > +             }
> > > > > > > +     }
> > > > > > > +
> > > > > > > +     if (cp == DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
> > > > > > > +             if (ctx->hdcp_cp !=
> > > > DRM_MODE_CONTENT_PROTECTION_ENABLED) {
> > > > > > > +                     dev_err(dev, "current CP is not ENABLED\n");
> > > > > > > +                     return;
> > > > > > > +             }
> > > > > > > +
> > > > > > > +             anx7625_hdcp_disable_and_update_cp(ctx);
> > > > > > > +     }
> > > > > > >  }
> > > > > > >
> > > > > > >  static void anx7625_bridge_atomic_disable(struct drm_bridge
> > > > > > > *bridge, @@ -2449,6 +2465,8 @@ static void
> > > > > > > anx7625_bridge_atomic_disable(struct
> > > > > > > drm_bridge *bridge,
> > > > > > >
> > > > > > >       dev_dbg(dev, "drm atomic disable\n");
> > > > > > >
> > > > > > > +     anx7625_hdcp_disable_and_update_cp(ctx);
> > > > > > > +
> > > > > > >       ctx->connector = NULL;
> > > > > > >       anx7625_dp_stop(ctx);
> > > > > > >
> > > > > > > --
> > > > > > > 2.25.1
> > > > > > >
> > > > > >
> > > > > > --
> > > > > > With best wishes
> > > > > > Dmitry
> > > >
> > > > --
> > > > With best wishes
> > > > Dmitry
> > 
> > 
> > 
> > --
> > With best wishes
> > Dmitry

-- 
With best wishes
Dmitry



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