Re: [PATCH 2/3] usb: typec: ps883x: fix missing accessibility check

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Tue, Feb 18, 2025 at 04:29:32PM +0100, Johan Hovold wrote:
> Make sure that the retimer is accessible before registering to avoid
> having later consumer calls fail to configure it, something which, for
> example, can lead to a hotplugged display not being recognised:
> 
> 	[drm:msm_dp_panel_read_sink_caps [msm]] *ERROR* read dpcd failed -110
> 
> Fixes: 257a087c8b52 ("usb: typec: Add support for Parade PS8830 Type-C Retimer")
> Cc: Abel Vesa <abel.vesa@linaro.org>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  drivers/usb/typec/mux/ps883x.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/drivers/usb/typec/mux/ps883x.c b/drivers/usb/typec/mux/ps883x.c
> index 274de7abe585..f8b47187f4cf 100644
> --- a/drivers/usb/typec/mux/ps883x.c
> +++ b/drivers/usb/typec/mux/ps883x.c
> @@ -291,6 +291,7 @@ static int ps883x_retimer_probe(struct i2c_client *client)
>  	struct typec_switch_desc sw_desc = { };
>  	struct typec_retimer_desc rtmr_desc = { };
>  	struct ps883x_retimer *retimer;
> +	unsigned int val;
>  	int ret;
>  
>  	retimer = devm_kzalloc(dev, sizeof(*retimer), GFP_KERNEL);
> @@ -360,6 +361,16 @@ static int ps883x_retimer_probe(struct i2c_client *client)
>  
>  		/* firmware initialization delay */
>  		msleep(60);
> +
> +		/* make sure device is accessible */
> +		ret = regmap_read(retimer->regmap, REG_USB_PORT_CONN_STATUS_0,
> +				  &val);
> +		if (ret) {
> +			dev_err(dev, "failed to read conn_status_0: %d\n", ret);
> +			if (ret == -ENXIO)
> +				ret = -EIO;
> +			goto err_clk_disable;
> +		}
>  	}
>  
>  	sw_desc.drvdata = retimer;
> -- 
> 2.45.3

-- 
heikki