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

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Oct 18, 2024 at 03:36:48PM +0200, Geert Uytterhoeven wrote:
> Hi Laurent,
> 
> CC GregKH
> 
> On Fri, Oct 18, 2024 at 3:10 PM Laurent Pinchart
> <laurent.pinchart@ideasonboard.com> wrote:
> > On Fri, Oct 18, 2024 at 09:45:52AM +0200, Geert Uytterhoeven 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.
> >
> > Isn't this something that should be handled by the AUX core ? The code
> > below would otherwise need to be duplicated by all drivers, which seems
> > a burden we should avoid.
> 
> According to the documentation, this is the responsibility of the caller
> https://elixir.bootlin.com/linux/v6.11.4/source/include/linux/auxiliary_bus.h#L81
> I believe this is the same for platform devices.
> See also the example at
> https://elixir.bootlin.com/linux/v6.11.4/source/include/linux/auxiliary_bus.h#L116
> 
> Note: the platform bus supports PLATFORM_DEVID_AUTO, but the auxiliary
> bus does not.

Yes, it does not as it's up to the caller to create a unique name, like
your patch here does.  I'd argue that platform should also not do
automatic device ids, but that's a different argument :)

This change looks good to me!

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>