On Tue, Dec 10, 2024 at 03:18:46PM +0100, 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. 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.
As I'd like to get a proper solution for this I'm not going to ack this
patch, but I won't nack it either.
> v2:
> - Use I2C adapter/address instead of ida_alloc().
> ---
> drivers/gpu/drm/bridge/ti-sn65dsi86.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi86.c b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> index 9e31f750fd889745..fb452d1b46995673 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi86.c
> @@ -480,6 +480,7 @@ static int ti_sn65dsi86_add_aux_device(struct ti_sn65dsi86 *pdata,
> const char *name)
> {
> struct device *dev = pdata->dev;
> + const struct i2c_client *client = to_i2c_client(dev);
> struct auxiliary_device *aux;
> int ret;
>
> @@ -488,6 +489,7 @@ static int ti_sn65dsi86_add_aux_device(struct ti_sn65dsi86 *pdata,
> return -ENOMEM;
>
> aux->name = name;
> + aux->id = (client->adapter->nr << 10) | client->addr;
> aux->dev.parent = dev;
> aux->dev.release = ti_sn65dsi86_aux_device_release;
> device_set_of_node_from_dev(&aux->dev, dev);
--
Regards,
Laurent Pinchart
