Re: [PATCH v3 2/3] mmc: sdhci-of-arasan: add phy support for sdhci-of-arasan

[Ulf Hansson]

+ Kishon

On 20 October 2015 at 09:05, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote:
> This patch adds Generic PHY access for sdhci-of-arasan. Driver
> can get PHY handler from dt-binding, and power-on/init the PHY.
> Also we add pm ops for PHY here if CONFIG_PM_SLEEP is enabled.
> Currently, it's just mandatory for arasan,sdhci-5.1.
>
> Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
>
> Serise-changes: 3
> - remove phy_init/exit for suspend/resume
> - adjust phy_int/power_on seq to make code more reasonable
> - simplify suspend/resume_phy
>
> Serise-changes: 2
> - Keep phy as a mandatory requirement for arasan,sdhci-5.1
>
> ---
>
> Changes in v2: None
>
>  drivers/mmc/host/sdhci-of-arasan.c | 87 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 87 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index 75379cb..85bd0f9d 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -21,6 +21,7 @@
>
>  #include <linux/module.h>
>  #include <linux/of_device.h>
> +#include <linux/phy/phy.h>
>  #include "sdhci-pltfm.h"
>
>  #define SDHCI_ARASAN_CLK_CTRL_OFFSET   0x2c
> @@ -35,6 +36,7 @@
>   */
>  struct sdhci_arasan_data {
>         struct clk      *clk_ahb;
> +       struct phy      *phy;
>  };
>
>  static unsigned int sdhci_arasan_get_timeout_clock(struct sdhci_host *host)
> @@ -70,6 +72,42 @@ static struct sdhci_pltfm_data sdhci_arasan_pdata = {
>
>  #ifdef CONFIG_PM_SLEEP
>  /**
> +  * sdhci_arasan_suspend_phy - Suspend phy method for the driver
> +  * @phy:        Handler of phy structure
> +  * Returns 0 on success and error value on error
> +  *
> +  * Put the phy in a deactive state.
> +  */
> +static int sdhci_arasan_suspend_phy(struct phy *phy)
> +{
> +       int ret = 0;
> +
> +       ret = phy_power_off(phy);
> +       if (ret)

This is an odd error handling, should you really do phy_power_on()?

> +               phy_power_on(phy);
> +
> +       return ret;
> +}
> +
> +/**
> +  * sdhci_arasan_resume_phy - Resume phy method for the driver
> +  * @phy:        Handler of phy structure
> +  * Returns 0 on success and error value on error
> +  *
> +  * Put the phy in a active state.
> +  */
> +static int sdhci_arasan_resume_phy(struct phy *phy)
> +{
> +       int ret = 0;
> +
> +       ret = phy_power_on(phy);
> +       if (ret)

Similar comment as above.

> +               phy_power_off(phy);
> +
> +       return ret;
> +}
> +
> +/**
>   * sdhci_arasan_suspend - Suspend method for the driver
>   * @dev:       Address of the device structure
>   * Returns 0 on success and error value on error
> @@ -88,6 +126,15 @@ static int sdhci_arasan_suspend(struct device *dev)
>         if (ret)
>                 return ret;
>
> +       if (!IS_ERR(sdhci_arasan->phy)) {
> +               ret = sdhci_arasan_suspend_phy(sdhci_arasan->phy);
> +               if (ret) {
> +                       dev_err(dev, "Cannot suspend phy.\n");
> +                       sdhci_resume_host(host);

This is an odd error handling, why do sdhci_resume_host()?

> +                       return ret;
> +               }
> +       }
> +
>         clk_disable(pltfm_host->clk);
>         clk_disable(sdhci_arasan->clk_ahb);
>
> @@ -122,6 +169,16 @@ static int sdhci_arasan_resume(struct device *dev)
>                 return ret;
>         }
>
> +       if (!IS_ERR(sdhci_arasan->phy)) {
> +               ret = sdhci_arasan_resume_phy(sdhci_arasan->phy);
> +               if (ret) {
> +                       dev_err(dev, "Cannot resume phy.\n");
> +                       clk_disable(sdhci_arasan->clk_ahb);
> +                       clk_disable(pltfm_host->clk);
> +                       return ret;

The error handling is starting to be a bit complex in
sdhci_arasan_resume(), perhaps it's time to add some labels to make
the code more readable?

> +               }
> +       }
> +
>         return sdhci_resume_host(host);
>  }
>  #endif /* ! CONFIG_PM_SLEEP */
> @@ -166,6 +223,33 @@ static int sdhci_arasan_probe(struct platform_device *pdev)
>                 goto clk_dis_ahb;
>         }
>
> +       sdhci_arasan->phy = NULL;

NULL isn't an error. You probably want something like:
sdhci_arasan->phy = ERR_PTR(-ENODEV);

Although, I just realize that the phy API works a bit differently than
other APIs. More precisely, instead of returning an error while you
provide a NULL pointer to the APIs, it will treat it as a NOOP and
return a non-error code (at least according to the documentation). I
don't know why the phy API is different, but to me I prefer to use the
regular kernel style and thus, please adopt to my suggestion above.

> +       if (of_device_is_compatible(pdev->dev.of_node,
> +                                   "arasan,sdhci-5.1")) {
> +               sdhci_arasan->phy = devm_phy_get(&pdev->dev,
> +                                                "phy_arasan");
> +               if (IS_ERR(sdhci_arasan->phy)) {
> +                       ret = -ENODEV;

You should give "ret" the error code from devm_phy_get(), via
PTR_ERR(sdhci_arasan->phy).

> +                       dev_err(&pdev->dev, "No phy for arasan,sdhci-5.1.\n");
> +                       goto clk_dis_ahb;
> +               }
> +
> +               ret = phy_init(sdhci_arasan->phy);
> +               if (ret < 0) {
> +                       dev_err(&pdev->dev, "phy_init err.\n");
> +                       phy_exit(sdhci_arasan->phy);

phy_exit(), that seems like and odd error handling as the phy_init() failed.

> +                       goto clk_dis_ahb;
> +               }
> +
> +               ret = phy_power_on(sdhci_arasan->phy);
> +               if (ret < 0) {
> +                       dev_err(&pdev->dev, "phy_power_on err.\n");
> +                       phy_power_off(sdhci_arasan->phy);

Similar comment as above.

> +                       phy_exit(sdhci_arasan->phy);
> +                       goto clk_dis_ahb;
> +               }
> +       }
> +

I believe you need at least phy_exit() if a failure occurs after this
point!? Perhaps some new error labels will deal with this nicely!?

>         host = sdhci_pltfm_init(pdev, &sdhci_arasan_pdata, 0);
>         if (IS_ERR(host)) {
>                 ret = PTR_ERR(host);
> @@ -210,6 +294,9 @@ static int sdhci_arasan_remove(struct platform_device *pdev)
>         struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>         struct sdhci_arasan_data *sdhci_arasan = pltfm_host->priv;
>
> +       if (!IS_ERR(sdhci_arasan->phy))
> +               phy_exit(sdhci_arasan->phy);
> +
>         clk_disable_unprepare(sdhci_arasan->clk_ahb);
>
>         return sdhci_pltfm_unregister(pdev);
> --
> 2.3.7
>
>
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