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

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Message-ID: <CAMuHMdW4w=zpLY0g6hdUN9-NTmmcpaqH5XxCCNSeu6oQsre8fw@mail.gmail.com>
Date: Tue, 7 Jan 2025 18:39:14 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Doug Anderson <dianders@...omium.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 Doug,

On Tue, Jan 7, 2025 at 6:27 PM Doug Anderson <dianders@...omium.org> wrote:
> On Wed, Dec 11, 2024 at 12:27 AM Geert Uytterhoeven
> <geert@...ux-m68k.org> wrote:
> > 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.

So the DRM tools don't use the latest version from linux-next yet...
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/scripts/checkpatch.pl?id=6356f18f09dc0781650c4f128ea48745fa48c415

> > > > 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

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds