Re: [PATCH] drm/bridge: anx7625: Don't log an error when DSI host can't be found

[AngeloGioacchino Del Regno]

Il 26/02/24 22:20, Nícolas F. R. A. Prado ha scritto:
> Given that failing to find a DSI host causes the driver to defer probe,
> make use of dev_err_probe() to log the reason. This makes the defer
> probe reason available and avoids alerting userspace about something
> that is not necessarily an error.
>
> Fixes: 269332997a16 ("drm/bridge: anx7625: Return -EPROBE_DEFER if the dsi host was not found")
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@xxxxxxxxxxxxx>
> ---
>   drivers/gpu/drm/bridge/analogix/anx7625.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index 29d91493b101..4ee5614a2623 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -2076,10 +2076,8 @@ static int anx7625_setup_dsi_device(struct anx7625_data *ctx)
>   	};
>   
>   	host = of_find_mipi_dsi_host_by_node(ctx->pdata.mipi_host_node);
> -	if (!host) {
> -		DRM_DEV_ERROR(dev, "fail to find dsi host.\n");
> -		return -EPROBE_DEFER;
> -	}
> +	if (!host)
> +		return dev_err_probe(dev, -EPROBE_DEFER, "fail to find dsi host.\n");

Agreed, but while at it:
 1. This is not the only driver doing this, so you might as well go fix all of them
    in a series (toshiba tcxxxx, lontium, chipone.... check them, the error message
    is exactly the same even, that'd take 3 seconds);
 2. I've just noticed that, in this driver, of_node_put() is never called for the
    `mipi_host_node`, so the reference is never dropped... but that can come later
    and not necessarily in the eventual series that fixes the err message strategy.

In the meanwhile, for this commit

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>

>   
>   	dsi = devm_mipi_dsi_device_register_full(dev, host, &info);
>   	if (IS_ERR(dsi)) {
>
> ---
> base-commit: 2ae0a045e6814c8c1d676d6153c605a65746aa29
> change-id: 20240226-anx7625-defer-log-no-dsi-host-c3f9ccbcb287
>
> Best regards,