linux-kernel - Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status at atomic

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Message-ID: <CAEXTbpf3Bipid7bgnYzGJ6C6d+pgPcA2mjwFijSBwz_6Ub4aaw@mail.gmail.com>
Date: Mon, 16 Dec 2024 20:05:00 +0800
From: Pin-yen Lin <treapking@...omium.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Xin Ji <xji@...logixsemi.com>, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	Laurent Pinchart <Laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Bernie Liang <bliang@...logixsemi.com>, Qilin Wen <qwen@...logixsemi.com>, 
	"treapking@...gle.com" <treapking@...gle.com>, 
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status at atomic_enable()

Hi Dmitry,

On Mon, Dec 16, 2024 at 7:59 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Mon, Dec 16, 2024 at 08:33:23AM +0000, Xin Ji wrote:
> > > -----Original Message-----
> > > From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > > Sent: Friday, December 13, 2024 9:17 PM
> > > To: Xin Ji <xji@...logixsemi.com>
> > > Cc: Andrzej Hajda <andrzej.hajda@...el.com>; Neil Armstrong
> > > <neil.armstrong@...aro.org>; Robert Foss <rfoss@...nel.org>; Laurent Pinchart
> > > <Laurent.pinchart@...asonboard.com>; Jonas Karlman <jonas@...boo.se>;
> > > Jernej Skrabec <jernej.skrabec@...il.com>; Maarten Lankhorst
> > > <maarten.lankhorst@...ux.intel.com>; Maxime Ripard <mripard@...nel.org>;
> > > Thomas Zimmermann <tzimmermann@...e.de>; David Airlie
> > > <airlied@...il.com>; Simona Vetter <simona@...ll.ch>; Bernie Liang
> > > <bliang@...logixsemi.com>; Qilin Wen <qwen@...logixsemi.com>;
> > > treapking@...gle.com; dri-devel@...ts.freedesktop.org; linux-
> > > kernel@...r.kernel.org
> > > 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@...logixsemi.com> 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.

I believe you mean "DESIRED" here.
>
> 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?

The bridge could be powered off between .atomic_disable() and
.atomic_enable(), though I'm not sure if this would be a concern for
anx7625. I'll let Xin to comment on this.
>
> > > >
> > > > Thanks!
> > > > Xin
> > > >
> > > > > -----Original Message-----
> > > > > From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > > > > Sent: Friday, December 13, 2024 6:47 PM
> > > > > To: Xin Ji <xji@...logixsemi.com>
> > > > > Cc: Andrzej Hajda <andrzej.hajda@...el.com>; Neil Armstrong
> > > > > <neil.armstrong@...aro.org>; Robert Foss <rfoss@...nel.org>; Laurent
> > > > > Pinchart <Laurent.pinchart@...asonboard.com>; Jonas Karlman
> > > > > <jonas@...boo.se>; Jernej Skrabec <jernej.skrabec@...il.com>;
> > > > > Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>; Maxime Ripard
> > > > > <mripard@...nel.org>; Thomas Zimmermann <tzimmermann@...e.de>;
> > > David
> > > > > Airlie <airlied@...il.com>; Simona Vetter <simona@...ll.ch>; Bernie
> > > > > Liang <bliang@...logixsemi.com>; Qilin Wen <qwen@...logixsemi.com>;
> > > > > treapking@...gle.com; dri-devel@...ts.freedesktop.org; linux-
> > > > > kernel@...r.kernel.org
> > > > > 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@...aro.org>
> > > > > > > Sent: Thursday, December 12, 2024 5:18 PM
> > > > > > > To: Xin Ji <xji@...logixsemi.com>
> > > > > > > Cc: Andrzej Hajda <andrzej.hajda@...el.com>; Neil Armstrong
> > > > > > > <neil.armstrong@...aro.org>; Robert Foss <rfoss@...nel.org>;
> > > > > > > Laurent Pinchart <Laurent.pinchart@...asonboard.com>; Jonas
> > > > > > > Karlman <jonas@...boo.se>; Jernej Skrabec
> > > > > > > <jernej.skrabec@...il.com>; Maarten Lankhorst
> > > > > > > <maarten.lankhorst@...ux.intel.com>; Maxime Ripard
> > > > > > > <mripard@...nel.org>; Thomas Zimmermann <tzimmermann@...e.de>;
> > > > > David
> > > > > > > Airlie <airlied@...il.com>; Simona Vetter <simona@...ll.ch>;
> > > > > > > Bernie Liang <bliang@...logixsemi.com>; Qilin Wen
> > > > > > > <qwen@...logixsemi.com>; treapking@...gle.com;
> > > > > > > dri-devel@...ts.freedesktop.org; linux- kernel@...r.kernel.org
> > > > > > > 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@...logixsemi.com>
> > > > > > > > ---
> > > > > > > >  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

Regards,
Pin-yen