Re: [PATCH] usb: typec: fsa4480: Relax CHIP_ID check

["Luca Weiss" <luca.weiss@fairphone.com>]

On Sun Aug 18, 2024 at 10:21 PM CEST, Luca Weiss wrote:
> Some FSA4480-compatible chips like the OCP96011 used on Fairphone 5
> return 0x00 from the CHIP_ID register. Handle that gracefully and only
> fail probe when the I2C read has failed.
>
> With this the dev_dbg will print 0 but otherwise continue working.
>
>   [    0.251581] fsa4480 1-0042: Found FSA4480 v0.0 (Vendor ID = 0)

Short appendix: just checked the OCP96011 datasheet and it does mention
register 00H being "Device ID" and "Reset Value" being 0x00 so that's
expected behavior on this specific chip.

Regards
Luca

>
> Cc: stable@vger.kernel.org
> Fixes: e885f5f1f2b4 ("usb: typec: fsa4480: Check if the chip is really there")
> Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
> ---
>  drivers/usb/typec/mux/fsa4480.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.c
> index cd235339834b..f71dba8bf07c 100644
> --- a/drivers/usb/typec/mux/fsa4480.c
> +++ b/drivers/usb/typec/mux/fsa4480.c
> @@ -274,7 +274,7 @@ static int fsa4480_probe(struct i2c_client *client)
>  		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");
>  
>  	ret = regmap_read(fsa->regmap, FSA4480_DEVICE_ID, &val);
> -	if (ret || !val)
> +	if (ret)
>  		return dev_err_probe(dev, -ENODEV, "FSA4480 not found\n");
>  
>  	dev_dbg(dev, "Found FSA4480 v%lu.%lu (Vendor ID = %lu)\n",
>
> ---
> base-commit: ccdbf91fdf5a71881ef32b41797382c4edd6f670
> change-id: 20240818-fsa4480-chipid-fix-2c7cf5810135
>
> Best regards,