linux-kernel - Re: [PATCH v2] drm/bridge: ti-sn65dsi86: Fix multiple instances

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

Message-ID: <CAD=FV=VONgQgohhtO07tQ4Paif_v1h+xrdAT8S8amkCc5rfgGw@mail.gmail.com>
Date: Tue, 7 Jan 2025 09:21:36 -0800
From: Doug Anderson <dianders@...omium.org>
To: Geert Uytterhoeven <geert@...ux-m68k.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>, 
	Linus Walleij <linus.walleij@...aro.org>, Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
	Wolfram Sang <wsa+renesas@...g-engineering.com>, 
	Luca Ceresoli <luca.ceresoli@...tlin.com>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
	Greg KH <gregkh@...uxfoundation.org>, dri-devel@...ts.freedesktop.org, 
	linux-renesas-soc@...r.kernel.org, linux-i2c@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/bridge: ti-sn65dsi86: Fix multiple instances

Hi

On Wed, Dec 11, 2024 at 12:27 AM Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
>
> Hi Doug,
>
> On Tue, Dec 10, 2024 at 6:09 PM Doug Anderson <dianders@...omium.org> wrote:
> > On Tue, Dec 10, 2024 at 6:19 AM Geert Uytterhoeven
> > <geert+renesas@...der.be> wrote:
> > > Each bridge instance creates up to four auxiliary devices with different
> > > names.  However, their IDs are always zero, causing duplicate filename
> > > errors when a system has multiple bridges:
> > >
> > >     sysfs: cannot create duplicate filename '/bus/auxiliary/devices/ti_sn65dsi86.gpio.0'
> > >
> > > Fix this by using a unique instance ID per bridge instance.  The
> > > instance ID is derived from the I2C adapter number and the bridge's I2C
> > > address, to support multiple instances on the same bus.
> > >
> > > Fixes: bf73537f411b0d4f ("drm/bridge: ti-sn65dsi86: Break GPIO and MIPI-to-eDP bridge into sub-drivers")

When I applied the patch, the DRM tools ran checkpatch in strict mode
which pointed out that you have too many digits in your "Fixes" hash.
I've adjusted them to make checkpatch happy.


> > > Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> > > ---
> > > On the White Hawk development board:
> > >
> > >     /sys/bus/auxiliary/devices/
> > >     |-- ti_sn65dsi86.aux.1068
> > >     |-- ti_sn65dsi86.aux.4140
> > >     |-- ti_sn65dsi86.bridge.1068
> > >     |-- ti_sn65dsi86.bridge.4140
> > >     |-- ti_sn65dsi86.gpio.1068
> > >     |-- ti_sn65dsi86.gpio.4140
> > >     |-- ti_sn65dsi86.pwm.1068
> > >     `-- ti_sn65dsi86.pwm.4140
> > >
> > > Discussion after v1:
> > >   - https://lore.kernel.org/8c2df6a903f87d4932586b25f1d3bd548fe8e6d1.1729180470.git.geert+renesas@glider.be
> > >
> > > Notes:
> > >   - While the bridge supports only two possible I2C addresses, I2C
> > >     translators may be present, increasing the address space.  Hence the
> > >     instance ID calculation assumes 10-bit addressing.  Perhaps it makes
> > >     sense to introduce a global I2C helper function for this?
> > >
> > >   - I think this is the simplest solution.  If/when the auxiliary bus
> > >     receives support à la PLATFORM_DEVID_AUTO, the driver can be
> > >     updated.
> > >
> > > v2:
> > >   - Use I2C adapter/address instead of ida_alloc().
> > > ---
> > >  drivers/gpu/drm/bridge/ti-sn65dsi86.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> >
> > While I agree with Laurent that having a more automatic solution would
> > be nice, this is small and fixes a real problem. I'd be of the opinion
> > that we should land it.
> >
> > Reviewed-by: Douglas Anderson <dianders@...omium.org>
>
> Thanks!
>
> > If I personally end up being the person to land it, I'll likely wait
> > until January since I'll be on vacation soon for the holidays and I
> > don't want to check something that's slightly controversial in and
> > then disappear. If someone else feels it's ready to land before then I
> > have no objections.
>
> There is no need to hurry. The only board I have that needs this has
> another issue in its second display pipeline, which will require a
> new driver no one is working on yet.

As promised, I've landed this. In this case I've landed in
drm-misc-next. Even though it's a fix since it didn't sound urgent
enough to land in drm-misc-fixes. Since it changes sysfs paths
slightly, it feels like it would be good to give it extra bake time
and not rush it as a fix.

[1/1] drm/bridge: ti-sn65dsi86: Fix multiple instances
      commit: 574f5ee2c85a00a579549d50e9fc9c6c072ee4c4

-Doug