Hi,
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>
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.
-Doug
