linux-kernel - Re: [PATCH v6] drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort connector type

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAD=FV=UiTh+HUoxWEmn8r-9wJtJqN0cnnZ_fKYZCt20NHGrZAQ@mail.gmail.com>
Date: Wed, 25 Jun 2025 07:52:26 -0700
From: Doug Anderson <dianders@...omium.org>
To: Jayesh Choudhary <j-choudhary@...com>
Cc: andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, dri-devel@...ts.freedesktop.org, 
	devarsht@...com, tomi.valkeinen@...asonboard.com, 
	kieran.bingham+renesas@...asonboard.com, ernest.vanhoecke@...adex.com, 
	jonas@...boo.se, jernej.skrabec@...il.com, maarten.lankhorst@...ux.intel.com, 
	mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch, 
	linux-kernel@...r.kernel.org, max.oss.09@...il.com, geert@...ux-m68k.org
Subject: Re: [PATCH v6] drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort
 connector type

Hi,

On Tue, Jun 24, 2025 at 1:59 PM Doug Anderson <dianders@...omium.org> wrote:
>
> Hi,
>
> On Mon, Jun 23, 2025 at 9:48 PM Jayesh Choudhary <j-choudhary@...com> wrote:
> >
> > By default, HPD was disabled on SN65DSI86 bridge. When the driver was
> > added (commit "a095f15c00e27"), the HPD_DISABLE bit was set in pre-enable
> > call which was moved to other function calls subsequently.
> > Later on, commit "c312b0df3b13" added detect utility for DP mode. But with
> > HPD_DISABLE bit set, all the HPD events are disabled[0] and the debounced
> > state always return 1 (always connected state).
> >
> > Set HPD_DISABLE bit conditionally based on display sink's connector type.
> > Since the HPD_STATE is reflected correctly only after waiting for debounce
> > time (~100-400ms) and adding this delay in detect() is not feasible
> > owing to the performace impact (glitches and frame drop), remove runtime
> > calls in detect() and add hpd_enable()/disable() bridge hooks with runtime
> > calls, to detect hpd properly without any delay.
> >
> > [0]: <https://www.ti.com/lit/gpn/SN65DSI86> (Pg. 32)
> >
> > Fixes: c312b0df3b13 ("drm/bridge: ti-sn65dsi86: Implement bridge connector operations for DP")
> > Cc: Max Krummenacher <max.krummenacher@...adex.com>
> > Reviewed-by: Douglas Anderson <dianders@...omium.org>
> > Tested-by: Ernest Van Hoecke <ernest.vanhoecke@...adex.com>
> > Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
> > ---
> >
> > Changelog v5->v6:
> > - Drop pm_runtime_mark_last_busy()
> > - Pick up tags
> >
> > v5 patch link:
> > <https://lore.kernel.org/all/20250616093240.499094-1-j-choudhary@ti.com/>
> >
> > Changelog v4->v5:
> > - Make suspend asynchronous in hpd_disable()
> > - Update HPD_DISABLE in probe function to address the case for when
> >   comms are already enabled. Comments taken verbatim from [2]
> > - Update comments
> >
> > v4 patch link:
> > <https://lore.kernel.org/all/20250611052947.5776-1-j-choudhary@ti.com/>
> >
> > Changelog v3->v4:
> > - Remove "no-hpd" support due to backward compatibility issues
> > - Change the conditional from "no-hpd" back to connector type
> >   but still address [1]
> >
> > v3 patch link:
> > <https://lore.kernel.org/all/20250529110418.481756-1-j-choudhary@ti.com/>
> >
> > Changelog v2->v3:
> > - Change conditional based on no-hpd property to address [1]
> > - Remove runtime calls in detect() with appropriate comments
> > - Add hpd_enable() and hpd_disable() in drm_bridge_funcs
> >
> > v2 patch link:
> > <https://lore.kernel.org/all/20250508115433.449102-1-j-choudhary@ti.com/>
> >
> > Changelog v1->v2:
> > - Drop additional property in bindings and use conditional.
> > - Instead of register read for HPD state, use dpcd read which returns 0
> >   for success and error codes for no connection
> > - Add relevant history for the required change in commit message
> > - Drop RFC subject-prefix in v2
> > - Add "Cc:" tag
> >
> > v1 patch link:
> > <https://lore.kernel.org/all/20250424105432.255309-1-j-choudhary@ti.com/>
> >
> > [1]: <https://lore.kernel.org/all/mwh35anw57d6nvre3sguetzq3miu4kd43rokegvul7fk266lys@5h2euthpk7vq/>
> > [2]: <https://lore.kernel.org/all/CAD=FV=WvH73d78De3PrbiG7b6OaS_BysGtxQ=mJTj4z-h0LYWA@mail.gmail.com/>
> >
> >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 69 +++++++++++++++++++++++----
> >  1 file changed, 60 insertions(+), 9 deletions(-)
>
> I'll plan to push this to drm-misc-fixes tomorrow morning unless there
> are any objections or requests for me to wait.

Pushed to drm-misc-fixes:

[1/1] drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort connector type
      commit: 55e8ff842051b1150461d7595d8f1d033c69d66b