Re: [PATCH 1/2] usb: dwc2: Make having a phy optional

[Jules Maselbas <jmaselbas@kalray.eu>]

Hi Daniel,

On Wed, Sep 08, 2021 at 09:46:21AM +0200, Daniel Brát wrote:
> Despite using 'phy_optional_get' to get a 'usb2_phy' inside its probe,
> the driver would fail if it didnt find it. Also, there is no Kconfig
> dependency on 'CONFIG_GENERIC_PHY', so without it defined te phy
> functions are unimplemented and always return -ENOSYS making dwc2 probe
> always fail too. Since the 'dwc2->phy' is optional, the driver was
> modified to reflect this.
> Tested working on Raspberry Pi 3B+.
> 
> Signed-off-by: Daniel Brát <danek.brat@gmail.com>
> ---
>  drivers/usb/dwc2/dwc2.c | 38 ++++++++++++++++++++++----------------
>  1 file changed, 22 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/usb/dwc2/dwc2.c b/drivers/usb/dwc2/dwc2.c
> index 9893977b8..8f3f8da00 100644
> --- a/drivers/usb/dwc2/dwc2.c
> +++ b/drivers/usb/dwc2/dwc2.c
> @@ -72,20 +72,22 @@ static int dwc2_probe(struct device_d *dev)
>  	if (ret)
>  		goto clk_disable;
>  
> -	dwc2->phy = phy_optional_get(dev, "usb2-phy");
> -	if (IS_ERR(dwc2->phy)) {
> -		ret = PTR_ERR(dwc2->phy);
> -		goto clk_disable;
> +	if (IS_ENABLED(CONFIG_GENERIC_PHY)) {
> +		dwc2->phy = phy_optional_get(dev, "usb2-phy");
> +		if (!dwc2->phy || IS_ERR(dwc2->phy)) {
I think a better way to fix this would be have phy_optional_get to
return NULL when CONFIG_GENERIC_PHY is not enabled. That way this
fix is not limited to dwc2 driver.

NULL is an expected return value for phy_optional_get when there is
no phy, so that must not cause any issue in the driver.

> +			dev_warn(dev, "Didnt find any 'usb2-phy'\n");
> +			dwc2->phy = NULL;
> +		} else {
> +			ret = phy_power_on(dwc2->phy);
> +			if (ret)
> +				goto clk_disable;
> +
> +			ret = phy_init(dwc2->phy);
> +			if (ret)
> +				goto phy_power_off;
> +		}
>  	}
>  
> -	ret = phy_power_on(dwc2->phy);
> -	if (ret)
> -		goto clk_disable;
> -
> -	ret = phy_init(dwc2->phy);
> -	if (ret)
> -		goto phy_power_off;
> -
>  	ret = dwc2_check_core_version(dwc2);
>  	if (ret)
>  		goto error;
> @@ -120,9 +122,11 @@ static int dwc2_probe(struct device_d *dev)
>  
>  	return 0;
>  error:
> -	phy_exit(dwc2->phy);
> +	if (dwc2->phy)
> +		phy_exit(dwc2->phy);
This is not needed as phy_exit already tests for NULL phy.

>  phy_power_off:
> -	phy_power_off(dwc2->phy);
> +	if (dwc2->phy)
> +		phy_power_off(dwc2->phy);
Same for phy_power_off

>  clk_disable:
>  	clk_disable(dwc2->clk);
>  clk_put:
> @@ -140,8 +144,10 @@ static void dwc2_remove(struct device_d *dev)
>  	dwc2_host_uninit(dwc2);
>  	dwc2_gadget_uninit(dwc2);
>  
> -	phy_exit(dwc2->phy);
> -	phy_power_off(dwc2->phy);
> +	if (dwc2->phy) {
> +		phy_exit(dwc2->phy);
> +		phy_power_off(dwc2->phy);
> +	}
Same as above

>  }
>  
>  static const struct of_device_id dwc2_platform_dt_ids[] = {
> -- 
> 2.17.1
> 
> 
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