Re: [PATCH v2 2/3] drm/stm: dsi: add support of an optional regulator

[Philippe CORNU <philippe.cornu@st.com>]

Hi Yannick,


On 5/10/19 6:16 PM, Philippe Cornu wrote:
> Dear Yannick,
> Thank you for your patch,
> 
> I like better the new shorter commit heading, thank you.
> 
> 
> On 5/10/19 4:20 PM, Yannick Fertré wrote:
>> Add support of an optional regulator for the phy part of the DSI
>> controller.
>>
>> Signed-off-by: Yannick Fertré <yannick.fertre@st.com>
>> ---
>>   drivers/gpu/drm/stm/dw_mipi_dsi-stm.c | 45 
>> ++++++++++++++++++++++++++++++-----
>>   1 file changed, 39 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c 
>> b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>> index 1bef73e..22bd095 100644
>> --- a/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>> +++ b/drivers/gpu/drm/stm/dw_mipi_dsi-stm.c
>> @@ -9,6 +9,7 @@
>>   #include <linux/clk.h>
>>   #include <linux/iopoll.h>
>>   #include <linux/module.h>
>> +#include <linux/regulator/consumer.h>
>>   #include <drm/drmP.h>
>>   #include <drm/drm_mipi_dsi.h>
>>   #include <drm/bridge/dw_mipi_dsi.h>
>> @@ -76,6 +77,7 @@ struct dw_mipi_dsi_stm {
>>       u32 hw_version;
>>       int lane_min_kbps;
>>       int lane_max_kbps;
>> +    struct regulator *vdd_supply;
>>   };
>>   static inline void dsi_write(struct dw_mipi_dsi_stm *dsi, u32 reg, 
>> u32 val)
>> @@ -318,17 +320,31 @@ static int dw_mipi_dsi_stm_probe(struct 
>> platform_device *pdev)
>>           return PTR_ERR(dsi->base);
>>       }
>> +    dsi->vdd_supply = devm_regulator_get_optional(dev, "phy-dsi");
>> +    if (IS_ERR(dsi->vdd_supply)) {
>> +        ret = PTR_ERR(dsi->vdd_supply);
>> +        if (ret != -EPROBE_DEFER)
>> +            DRM_ERROR("failed to request regulator: %d\n", ret);
>> +        return ret;
>> +    }


I did more tests on a stm32f469 disco board and this above code does not 
work (the ret value is -ENODEV)

Two possibilities then:
1) remove the _optional (but we have the "using dummy regulator" 
message, I am fine with it)

or
2) handle -ENODEV but do not forget to check vdd_supply!=NULL before 
calling all regulator_(enable/disable)

	if (ret != -ENODEV) {
		if (ret != -EPROBE_DEFER)
			DRM_ERROR("failed to request regulator: %d\n",
				ret);
			return ret;
		}
		dsi->vdd_supply = NULL;
	}

	if (dsi->vdd_supply) {
		ret = regulator_enable(dsi->vdd_supply);
		...


	if (dsi->vdd_supply)
		regulator_disable(dsi->vdd_supply);


I let you choose your favorite one.

Thank you,
Philippe

>> +
>> +    ret = regulator_enable(dsi->vdd_supply);
>> +    if (ret) {
>> +        DRM_ERROR("failed to enable regulator: %d\n", ret);
>> +        return ret;
>> +    }
>> +
>>       dsi->pllref_clk = devm_clk_get(dev, "ref");
>>       if (IS_ERR(dsi->pllref_clk)) {
>>           ret = PTR_ERR(dsi->pllref_clk);
>> -        dev_err(dev, "Unable to get pll reference clock: %d\n", ret);
>> -        return ret;
>> +        DRM_ERROR("Unable to get pll reference clock: %d\n", ret);
>> +        goto err_clk_get;
>>       }
>>       ret = clk_prepare_enable(dsi->pllref_clk);
>>       if (ret) {
>> -        dev_err(dev, "%s: Failed to enable pllref_clk\n", __func__);
>> -        return ret;
>> +        DRM_ERROR("%s: Failed to enable pllref_clk\n", __func__);
>> +        goto err_clk_get;
>>       }
>>       dw_mipi_dsi_stm_plat_data.base = dsi->base;
>> @@ -339,11 +355,19 @@ static int dw_mipi_dsi_stm_probe(struct 
>> platform_device *pdev)
>>       dsi->dsi = dw_mipi_dsi_probe(pdev, &dw_mipi_dsi_stm_plat_data);
>>       if (IS_ERR(dsi->dsi)) {
>>           DRM_ERROR("Failed to initialize mipi dsi host\n");
>> -        clk_disable_unprepare(dsi->pllref_clk);
>> -        return PTR_ERR(dsi->dsi);
>> +        ret = PTR_ERR(dsi->dsi);
>> +        goto err_dsi_probe;
>>       }
>>       return 0;
>> +
>> +err_dsi_probe:
>> +    clk_disable_unprepare(dsi->pllref_clk);
>> +err_clk_get:
>> +    regulator_disable(dsi->vdd_supply);
>> +
>> +    return ret;
>> +
>>   }
>>   static int dw_mipi_dsi_stm_remove(struct platform_device *pdev)
>> @@ -351,6 +375,7 @@ static int dw_mipi_dsi_stm_remove(struct 
>> platform_device *pdev)
>>       struct dw_mipi_dsi_stm *dsi = platform_get_drvdata(pdev);
>>       clk_disable_unprepare(dsi->pllref_clk);
>> +    regulator_disable(dsi->vdd_supply);
>>       dw_mipi_dsi_remove(dsi->dsi);
> 
> for a future patch: we may have a different order
>      dw_mipi_dsi_remove(dsi->dsi);
>      clk_disable_unprepare(dsi->pllref_clk);
>      regulator_disable(dsi->vdd_supply);
> 
>>       return 0;
>> @@ -363,6 +388,7 @@ static int __maybe_unused 
>> dw_mipi_dsi_stm_suspend(struct device *dev)
>>       DRM_DEBUG_DRIVER("\n");
>>       clk_disable_unprepare(dsi->pllref_clk);
>> +    regulator_disable(dsi->vdd_supply);
>>       return 0;
>>   }
>> @@ -370,9 +396,16 @@ static int __maybe_unused 
>> dw_mipi_dsi_stm_suspend(struct device *dev)
>>   static int __maybe_unudw_mipi_dsi_remove(dsi->dsi);sed 
>> dw_mipi_dsi_stm_resume(struct device *dev)
>>   {
>>       struct dw_mipi_dsi_stm *dsi = dw_mipi_dsi_stm_plat_data.priv_data;
>> +    int ret;
>>       DRM_DEBUG_DRIVER("\n");
>> +    ret = regulator_enable(dsi->vdd_supply);
>> +    if (ret) {
>> +        DRM_ERROR("failed to enable regulator: %d\n", ret);
>> +        return ret;
>> +    }
>> +
>>       clk_prepare_enable(dsi->pllref_clk);
> 
> for a future patch: we may check clk_prepare_enable return value.
> 
>>       return 0;
>>
> 
> 
> Acked-by: Philippe Cornu <philippe.cornu@st.com>
> 
> Philippe :)
> 
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