[PATCH v3 1/3] phy: qcom-snps-femto-v2: properly enable ref clock

[Bjorn Andersson]

On Thu, Jun 22, 2023 at 03:40:18PM -0400, Adrien Thierry wrote:
> The driver is not enabling the ref clock, which thus gets disabled by
> the clk_disable_unused initcall. This leads to the dwc3 controller
> failing to initialize if probed after clk_disable_unused is called, for
> instance when the driver is built as a module.
> 
> To fix this, switch to the clk_bulk API to handle both cfg_ahb and ref
> clocks at the proper places.
> 
> Note that the cfg_ahb clock is currently not used by any device tree
> instantiation of the PHY. Work needs to be done separately to fix this.
> 
> Link: https://lore.kernel.org/linux-arm-msm/ZEqvy+khHeTkC2hf@fedora/
> Fixes: 51e8114f80d0 ("phy: qcom-snps: Add SNPS USB PHY driver for QCOM based SOCs")
> Reviewed-by: Andrew Halaney <ahalaney at redhat.com>
> Signed-off-by: Adrien Thierry <athierry at redhat.com>
> ---
>  drivers/phy/qualcomm/phy-qcom-snps-femto-v2.c | 67 ++++++++++++++-----
>  1 file changed, 49 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/phy/qualcomm/phy-qcom-snps-femto-v2.c b/drivers/phy/qualcomm/phy-qcom-snps-femto-v2.c
> index 6c237f3cc66d..ce1d2f8b568a 100644
> --- a/drivers/phy/qualcomm/phy-qcom-snps-femto-v2.c
> +++ b/drivers/phy/qualcomm/phy-qcom-snps-femto-v2.c
> @@ -110,11 +110,13 @@ struct phy_override_seq {
>  /**
>   * struct qcom_snps_hsphy - snps hs phy attributes
>   *
> + * @dev: device structure
> + *
>   * @phy: generic phy
>   * @base: iomapped memory space for snps hs phy
>   *
> - * @cfg_ahb_clk: AHB2PHY interface clock
> - * @ref_clk: phy reference clock
> + * @num_clks: number of clocks
> + * @clks: array of clocks
>   * @phy_reset: phy reset control
>   * @vregs: regulator supplies bulk data
>   * @phy_initialized: if PHY has been initialized correctly
> @@ -122,11 +124,13 @@ struct phy_override_seq {
>   * @update_seq_cfg: tuning parameters for phy init
>   */
>  struct qcom_snps_hsphy {
> +	struct device *dev;
> +
>  	struct phy *phy;
>  	void __iomem *base;
>  
> -	struct clk *cfg_ahb_clk;
> -	struct clk *ref_clk;
> +	int num_clks;
> +	struct clk_bulk_data *clks;
>  	struct reset_control *phy_reset;
>  	struct regulator_bulk_data vregs[SNPS_HS_NUM_VREGS];
>  
> @@ -135,6 +139,32 @@ struct qcom_snps_hsphy {
>  	struct phy_override_seq update_seq_cfg[NUM_HSPHY_TUNING_PARAMS];
>  };
>  
> +static int qcom_snps_hsphy_clk_init(struct qcom_snps_hsphy *hsphy)
> +{
> +	struct device *dev = hsphy->dev;
> +
> +	hsphy->num_clks = 2;
> +	hsphy->clks = devm_kcalloc(dev, hsphy->num_clks, sizeof(*hsphy->clks), GFP_KERNEL);

This is ok, but it it wouldn't be wrong to just make clks[2] in the
context struct...

> +	if (!hsphy->clks)
> +		return -ENOMEM;
> +
> +	/*
> +	 * HACK: For cfg_ahb clock, use devm_clk_get_optional() because currently no device

Doesn't look to hacky to me, this is how you use the API if you need to
do what you propose. So I would suggest dropping "HACK: For cfg_ahb
clock, ". The remainder of the comment is good to keep (if anything it's
a TODO, to drop this sometime in the future).

> +	 * tree instantiation of the PHY is using the clock. This needs to be fixed in order
> +	 * for this code to be able to use devm_clk_bulk_get().
> +	 */
> +	hsphy->clks[0].id = "cfg_ahb";
> +	hsphy->clks[0].clk = devm_clk_get_optional(dev, "cfg_ahb");

The clock is optional, but you still need to check for IS_ERR() in case
it's specified and there's an issue acquiring it.

> +
> +	hsphy->clks[1].id = "ref";
> +	hsphy->clks[1].clk = devm_clk_get(dev, "ref");
> +	if (IS_ERR(hsphy->clks[1].clk))
> +		return dev_err_probe(dev, PTR_ERR(hsphy->clks[1].clk),
> +				     "failed to get ref clk\n");
> +
> +	return 0;
> +}
> +
>  static inline void qcom_snps_hsphy_write_mask(void __iomem *base, u32 offset,
>  						u32 mask, u32 val)
>  {
> @@ -165,7 +195,7 @@ static int qcom_snps_hsphy_suspend(struct qcom_snps_hsphy *hsphy)
>  					   0, USB2_AUTO_RESUME);
>  	}
>  
> -	clk_disable_unprepare(hsphy->cfg_ahb_clk);
> +	clk_bulk_disable_unprepare(hsphy->num_clks, hsphy->clks);
>  	return 0;
>  }
>  
> @@ -175,9 +205,9 @@ static int qcom_snps_hsphy_resume(struct qcom_snps_hsphy *hsphy)
>  
>  	dev_dbg(&hsphy->phy->dev, "Resume QCOM SNPS PHY, mode\n");
>  
> -	ret = clk_prepare_enable(hsphy->cfg_ahb_clk);
> +	ret = clk_bulk_prepare_enable(hsphy->num_clks, hsphy->clks);
>  	if (ret) {
> -		dev_err(&hsphy->phy->dev, "failed to enable cfg ahb clock\n");
> +		dev_err(&hsphy->phy->dev, "failed to enable clocks\n");

You can omit this print completely, because clk_bulk_prepare() and
friends will log an error line telling you which clock failed to prepare
already.

>  		return ret;
>  	}
>  
> @@ -374,16 +404,16 @@ static int qcom_snps_hsphy_init(struct phy *phy)
>  	if (ret)
>  		return ret;
>  
> -	ret = clk_prepare_enable(hsphy->cfg_ahb_clk);
> +	ret = clk_bulk_prepare_enable(hsphy->num_clks, hsphy->clks);
>  	if (ret) {
> -		dev_err(&phy->dev, "failed to enable cfg ahb clock, %d\n", ret);
> +		dev_err(&phy->dev, "failed to enable clocks, %d\n", ret);

Here as well.

Regards,
Bjorn

>  		goto poweroff_phy;
>  	}
>  
>  	ret = reset_control_assert(hsphy->phy_reset);
>  	if (ret) {
>  		dev_err(&phy->dev, "failed to assert phy_reset, %d\n", ret);
> -		goto disable_ahb_clk;
> +		goto disable_clks;
>  	}
>  
>  	usleep_range(100, 150);
> @@ -391,7 +421,7 @@ static int qcom_snps_hsphy_init(struct phy *phy)
>  	ret = reset_control_deassert(hsphy->phy_reset);
>  	if (ret) {
>  		dev_err(&phy->dev, "failed to de-assert phy_reset, %d\n", ret);
> -		goto disable_ahb_clk;
> +		goto disable_clks;
>  	}
>  
>  	qcom_snps_hsphy_write_mask(hsphy->base, USB2_PHY_USB_PHY_CFG0,
> @@ -448,8 +478,8 @@ static int qcom_snps_hsphy_init(struct phy *phy)
>  
>  	return 0;
>  
> -disable_ahb_clk:
> -	clk_disable_unprepare(hsphy->cfg_ahb_clk);
> +disable_clks:
> +	clk_bulk_disable_unprepare(hsphy->num_clks, hsphy->clks);
>  poweroff_phy:
>  	regulator_bulk_disable(ARRAY_SIZE(hsphy->vregs), hsphy->vregs);
>  
> @@ -461,7 +491,7 @@ static int qcom_snps_hsphy_exit(struct phy *phy)
>  	struct qcom_snps_hsphy *hsphy = phy_get_drvdata(phy);
>  
>  	reset_control_assert(hsphy->phy_reset);
> -	clk_disable_unprepare(hsphy->cfg_ahb_clk);
> +	clk_bulk_disable_unprepare(hsphy->num_clks, hsphy->clks);
>  	regulator_bulk_disable(ARRAY_SIZE(hsphy->vregs), hsphy->vregs);
>  	hsphy->phy_initialized = false;
>  
> @@ -554,14 +584,15 @@ static int qcom_snps_hsphy_probe(struct platform_device *pdev)
>  	if (!hsphy)
>  		return -ENOMEM;
>  
> +	hsphy->dev = dev;
> +
>  	hsphy->base = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(hsphy->base))
>  		return PTR_ERR(hsphy->base);
>  
> -	hsphy->ref_clk = devm_clk_get(dev, "ref");
> -	if (IS_ERR(hsphy->ref_clk))
> -		return dev_err_probe(dev, PTR_ERR(hsphy->ref_clk),
> -				     "failed to get ref clk\n");
> +	ret = qcom_snps_hsphy_clk_init(hsphy);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to initialize clocks\n");
>  
>  	hsphy->phy_reset = devm_reset_control_get_exclusive(&pdev->dev, NULL);
>  	if (IS_ERR(hsphy->phy_reset)) {
> -- 
> 2.40.1
>