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

[Shawn Lin <shawn.lin@rock-chips.com>]

On 2015/10/20 16:39, Ulf Hansson wrote:
> + Kishon
>
> On 20 October 2015 at 09:05, Shawn Lin <shawn.lin@rock-chips.com> 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@rock-chips.com>
>>
>> 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()?
>

Thanks for these helpful comments.

Michal also mentioned this odd error handling. Well, I can't say whether 
it's okay, but at least large numbers of drivers which adopt generic phy 
interfaces don't even test the return value of power_off/on.

Anyway, remove this err handling is okay to me.
I will do it.

>> +               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.

Ditto.

>
>> +               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()?

right, no need there, sorry for the bit.

>
>> +                       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?

Agreed.

>
>> +               }
>> +       }
>> +
>>          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.
>

Got it.

>> +       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).

Ah, yes.

>
>> +                       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.

As above, I am going to remove it.

>
>> +                       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!?

right, I will do it.

>
>>          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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>


-- 
Best Regards
Shawn Lin