> -----Original Message----- > From: Dmitry Baryshkov <[email protected]> > Sent: Wednesday, December 18, 2024 6:32 PM > To: Xin Ji <[email protected]> > Cc: Pin-yen Lin <[email protected]>; Andrzej Hajda > <[email protected]>; Neil Armstrong <[email protected]>; > Robert Foss <[email protected]>; Laurent Pinchart > <[email protected]>; Jonas Karlman <[email protected]>; > Jernej Skrabec <[email protected]>; Maarten Lankhorst > <[email protected]>; Maxime Ripard <[email protected]>; > Thomas Zimmermann <[email protected]>; David Airlie > <[email protected]>; Simona Vetter <[email protected]>; Bernie Liang > <[email protected]>; Qilin Wen <[email protected]>; > [email protected]; [email protected]; linux- > [email protected] > Subject: Re: [PATCH v3] drm/bridge:anx7625: Update HDCP status at > atomic_enable() > > > On Wed, 18 Dec 2024 at 10:46, Xin Ji <[email protected]> wrote: > > > > > -----Original Message----- > > > From: Dmitry Baryshkov <[email protected]> > > > Sent: Tuesday, December 17, 2024 8:30 PM > > > To: Xin Ji <[email protected]> > > > Cc: Pin-yen Lin <[email protected]>; Andrzej Hajda > > > <[email protected]>; Neil Armstrong > > > <[email protected]>; Robert Foss <[email protected]>; Laurent > > > Pinchart <[email protected]>; Jonas Karlman > > > <[email protected]>; Jernej Skrabec <[email protected]>; > > > Maarten Lankhorst <[email protected]>; Maxime Ripard > > > <[email protected]>; Thomas Zimmermann <[email protected]>; > David > > > Airlie <[email protected]>; Simona Vetter <[email protected]>; Bernie > > > Liang <[email protected]>; Qilin Wen <[email protected]>; > > > [email protected]; [email protected]; linux- > > > [email protected] > > > 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 <[email protected]> > > > > > Sent: Monday, December 16, 2024 8:05 PM > > > > > To: Dmitry Baryshkov <[email protected]> > > > > > Cc: Xin Ji <[email protected]>; Andrzej Hajda > > > > > <[email protected]>; Neil Armstrong > > > > > <[email protected]>; Robert Foss <[email protected]>; > > > > > Laurent Pinchart <[email protected]>; Jonas > > > > > Karlman <[email protected]>; Jernej Skrabec > > > > > <[email protected]>; Maarten Lankhorst > > > > > <[email protected]>; Maxime Ripard > > > > > <[email protected]>; Thomas Zimmermann <[email protected]>; > > > David > > > > > Airlie <[email protected]>; Simona Vetter <[email protected]>; > > > > > Bernie Liang <[email protected]>; Qilin Wen > > > > > <[email protected]>; [email protected]; > > > > > [email protected]; linux- [email protected] > > > > > 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 > > > > > <[email protected]> wrote: > > > > > > > > > > > > On Mon, Dec 16, 2024 at 08:33:23AM +0000, Xin Ji wrote: > > > > > > > > -----Original Message----- > > > > > > > > From: Dmitry Baryshkov <[email protected]> > > > > > > > > Sent: Friday, December 13, 2024 9:17 PM > > > > > > > > To: Xin Ji <[email protected]> > > > > > > > > Cc: Andrzej Hajda <[email protected]>; Neil > > > > > > > > Armstrong <[email protected]>; Robert Foss > > > > > > > > <[email protected]>; Laurent Pinchart > > > > > > > > <[email protected]>; Jonas Karlman > > > > > > > > <[email protected]>; Jernej Skrabec > > > > > > > > <[email protected]>; Maarten Lankhorst > > > > > > > > <[email protected]>; Maxime Ripard > > > > > > > > <[email protected]>; Thomas Zimmermann > > > <[email protected]>; > > > > > > > > David Airlie <[email protected]>; Simona Vetter > > > > > > > > <[email protected]>; Bernie Liang <[email protected]>; > > > > > > > > Qilin Wen <[email protected]>; [email protected]; > > > > > > > > [email protected]; linux- > > > > > > > > [email protected] > > > > > > > > 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 <[email protected]> > > > > > > > > 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(). > > Finally! This phrase should be in the commit message. Hi Dmitry, OK, I'll add it in the commit message and send new patch. Thanks, Xin
> > > > > > > > > > > > > > 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->ctx->connector > > > without any protection. > > OK, I'll upstream another patch. > > > > > > -- > > > With best wishes > > > Dmitry > > > > -- > With best wishes > Dmitry
