Hi Doug,
On Tue, Dec 10, 2024 at 6:09 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote:
> On Tue, Dec 10, 2024 at 6:19 AM Geert Uytterhoeven
> <geert+renesas@xxxxxxxxx> 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")
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> > ---
> > 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@xxxxxxxxx
> >
> > 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@xxxxxxxxxxxx>
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.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
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
