Message-ID:
 <BY5PR04MB6739B4BEAEFD0292C1AC9E3FC7042@BY5PR04MB6739.namprd04.prod.outlook.com>
Date: Tue, 17 Dec 2024 01:50:00 +0000
From: Xin Ji <xji@...logixsemi.com>
To: Pin-yen Lin <treapking@...omium.org>, Dmitry Baryshkov
	<dmitry.baryshkov@...aro.org>
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"
	<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()

> -----Original Message-----
> From: Pin-yen Lin <treapking@...omium.org>
> Sent: Monday, December 16, 2024 8:05 PM
> 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; dri-devel@...ts.freedesktop.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_connecto
> r.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.
Hi Dmitry, the bridge driver is different with i915, anx7625 bridge driver
only implement some passive callback interface. There is no HDCP status
checking while do resolution switch.
> 
> 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.
The flow of resolution switch is:
    -> .atomic_disable().
        -> .atomic_enable().
            -> HDCP status check and enable.
As resolution switch is triggered by user space, at this moment, the HDCP
works fine(cannot get disabled event from HW). So, I think, .atomic_disable() is
the best place to do termination of authentication (turn HDCP status to DESIRED).
This is the only entrance which can do termination of authentication, I cannot
find others.

> >
> > > > >
> > > > > 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

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