> -----Original Message----- > From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > Sent: Tuesday, December 17, 2024 8:30 PM > To: Xin Ji <xji@xxxxxxxxxxxxxxxx> > Cc: Pin-yen Lin <treapking@xxxxxxxxxxxx>; 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() > > > On Tue, Dec 17, 2024 at 01:50:00AM +0000, Xin Ji wrote: > > > -----Original Message----- > > > From: Pin-yen Lin <treapking@xxxxxxxxxxxx> > > > Sent: Monday, December 16, 2024 8:05 PM > > > To: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > > > Cc: Xin Ji <xji@xxxxxxxxxxxxxxxx>; 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() > > > > > > > > > Hi Dmitry, > > > > > > On Mon, Dec 16, 2024 at 7:59 PM Dmitry Baryshkov > > > <dmitry.baryshkov@xxxxxxxxxx> wrote: > > > > > > > > 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_ > > > 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. > > Does that mean that you _have_ to reestablish HDCP after mode switching in > order for it to work? Hi Dmitry, anx7625 bridge IC will be power down after call .atomic_disable(), and all HDCP status will be lost on chip. So, we should reestablish HDCP again in .atomic_enable(). > > > > > > > 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. > > I'm probably still missing a reference to the standard (please excuse me, I don't > know it by heart). Is it a standard requirement to reauthenticate on the mode > switch? I'm not sure, but anx7625 have power cycle on the mode switch. All HDCP status Will be lost. > > BTW, while reading the anx7625 code, I noticed that there is a possible race > between .atomic_enable() / .atomic_disable() which set > ctx->connector and the hdcp_check_work_func() which reads ctx->connector > without any protection. OK, I'll upstream another patch. > > -- > With best wishes > Dmitry
