[PATCH v2 0/3] mmc: usdhi6rol0: UHS support

[PATCH v2 0/3] mmc: usdhi6rol0: UHS support

[Lars Persson]

This patch set adds UHS support to the usdhi6rol0 driver, with control of the
regulator and pin state settings.

Changes since v1:
- Use mmc_regulator_set_vqmmc().

Lars Persson (3):
  mmc: dt: usdhi6rol0: add optional pinctrl binding
  mmc: usdhi6rol0: add support for UHS modes
  mmc: usdhi6rol0: add pinctrl to set pin drive strength

 .../devicetree/bindings/mmc/usdhi6rol0.txt         |  4 ++
 drivers/mmc/host/usdhi6rol0.c                      | 51 ++++++++++++++++++++++
 2 files changed, 55 insertions(+)

-- 
2.1.4

[PATCH v2 1/3] mmc: dt: usdhi6rol0: add optional pinctrl binding

[Lars Persson]

Add a pinctrl binding to specify different pin settings for high speed
modes and UHS modes.

Signed-off-by: Lars Persson <larper-VrBV9hrLPhE@public.gmane.org>
---
 Documentation/devicetree/bindings/mmc/usdhi6rol0.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt b/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt
index 8babdaa..9dd9478 100644
--- a/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt
+++ b/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt
@@ -12,6 +12,10 @@ Optional properties:
 
 - vmmc-supply:	a phandle of a regulator, supplying Vcc to the card
 - vqmmc-supply:	a phandle of a regulator, supplying VccQ to the card
+- pinctrl-names: Must contain a "default" entry and optionally a "pins_uhs"
+                 entry for the UHS pin configuration.
+- pinctrl-N: One property for each name listed in pinctrl-names, see
+             ../pinctrl/pinctrl-bindings.txt.
 
 Additionally any standard mmc bindings from mmc.txt can be used.
 
-- 
2.1.4

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Re: [PATCH v2 1/3] mmc: dt: usdhi6rol0: add optional pinctrl binding

[Ulf Hansson]

On 18 April 2016 at 15:44, Lars Persson <lars.persson@axis.com> wrote:
> Add a pinctrl binding to specify different pin settings for high speed
> modes and UHS modes.
>
> Signed-off-by: Lars Persson <larper@axis.com>
> ---
>  Documentation/devicetree/bindings/mmc/usdhi6rol0.txt | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt b/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt
> index 8babdaa..9dd9478 100644
> --- a/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt
> +++ b/Documentation/devicetree/bindings/mmc/usdhi6rol0.txt
> @@ -12,6 +12,10 @@ Optional properties:
>
>  - vmmc-supply: a phandle of a regulator, supplying Vcc to the card
>  - vqmmc-supply:        a phandle of a regulator, supplying VccQ to the card
> +- pinctrl-names: Must contain a "default" entry and optionally a "pins_uhs"

"state_uhs" is becoming more and more widely deployed, I suggest you
use that as well.

Moreover, I am reviewing patch 3/3 and I think some more clarification
is needed here, on whether what is required and optional. See those
comment on patch 3/3.

> +                 entry for the UHS pin configuration.
> +- pinctrl-N: One property for each name listed in pinctrl-names, see
> +             ../pinctrl/pinctrl-bindings.txt.
>
>  Additionally any standard mmc bindings from mmc.txt can be used.
>
> --
> 2.1.4
>

Kind regards
Uffe

[PATCH v2 2/3] mmc: usdhi6rol0: add support for UHS modes

[Lars Persson]

Add a start_signal_voltage_switch() operation to support enabling of
UHS modes.

Signed-off-by: Lars Persson <larper@axis.com>
---
 drivers/mmc/host/usdhi6rol0.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
index 807c06e..2585ea4 100644
--- a/drivers/mmc/host/usdhi6rol0.c
+++ b/drivers/mmc/host/usdhi6rol0.c
@@ -1147,12 +1147,25 @@ static void usdhi6_enable_sdio_irq(struct mmc_host *mmc, int enable)
 	}
 }
 
+static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+	int ret;
+
+	ret = mmc_regulator_set_vqmmc(mmc, ios);
+
+	if (ret < 0)
+		dev_warn(mmc_dev(mmc), "Voltage switch failed: %d\n", ret);
+
+	return ret;
+}
+
 static struct mmc_host_ops usdhi6_ops = {
 	.request	= usdhi6_request,
 	.set_ios	= usdhi6_set_ios,
 	.get_cd		= usdhi6_get_cd,
 	.get_ro		= usdhi6_get_ro,
 	.enable_sdio_irq = usdhi6_enable_sdio_irq,
+	.start_signal_voltage_switch = usdhi6_sig_volt_switch,
 };
 
 /*			State machine handlers				*/
-- 
2.1.4

[PATCH v2 3/3] mmc: usdhi6rol0: add pinctrl to set pin drive strength

[Lars Persson]

Some boards need different pin drive strength for the UHS mode. Add an
optional pinctrl setting with two pin states covering UHS speeds and
other speeds.

Signed-off-by: Lars Persson <larper@axis.com>
---
 drivers/mmc/host/usdhi6rol0.c | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
index 2585ea4..e8a5c8f 100644
--- a/drivers/mmc/host/usdhi6rol0.c
+++ b/drivers/mmc/host/usdhi6rol0.c
@@ -22,6 +22,7 @@
 #include <linux/mmc/sdio.h>
 #include <linux/module.h>
 #include <linux/pagemap.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/scatterlist.h>
 #include <linux/string.h>
@@ -198,6 +199,11 @@ struct usdhi6_host {
 	struct dma_chan *chan_rx;
 	struct dma_chan *chan_tx;
 	bool dma_active;
+
+	/* Pin control */
+	struct pinctrl *pinctrl;
+	struct pinctrl_state *pins_default;
+	struct pinctrl_state *pins_uhs;
 };
 
 /*			I/O primitives					*/
@@ -1147,14 +1153,39 @@ static void usdhi6_enable_sdio_irq(struct mmc_host *mmc, int enable)
 	}
 }
 
+static int usdhi6_set_pinstates(struct usdhi6_host *host, int voltage)
+{
+	if (IS_ERR(host->pinctrl) || IS_ERR(host->pins_default) ||
+	    IS_ERR(host->pins_uhs))
+		return 0;
+
+	switch (voltage) {
+	case MMC_SIGNAL_VOLTAGE_180:
+	case MMC_SIGNAL_VOLTAGE_120:
+		return pinctrl_select_state(host->pinctrl,
+					    host->pins_uhs);
+
+	default:
+		return pinctrl_select_state(host->pinctrl,
+					    host->pins_default);
+	}
+}
+
 static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	int ret;
 
 	ret = mmc_regulator_set_vqmmc(mmc, ios);
 
-	if (ret < 0)
+	if (ret < 0) {
 		dev_warn(mmc_dev(mmc), "Voltage switch failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = usdhi6_set_pinstates(mmc_priv(mmc), ios->signal_voltage);
+	if (ret)
+		dev_warn_once(mmc_dev(mmc),
+			      "Failed to set pinstate err=%d\n", ret);
 
 	return ret;
 }
@@ -1817,6 +1848,13 @@ static int usdhi6_probe(struct platform_device *pdev)
 		mmc->f_max = host->imclk;
 	mmc->f_min = host->imclk / 512;
 
+	host->pinctrl = devm_pinctrl_get(&pdev->dev);
+	if (!IS_ERR(host->pinctrl)) {
+		host->pins_default = pinctrl_lookup_state(host->pinctrl,
+							  PINCTRL_STATE_DEFAULT);
+		host->pins_uhs     = pinctrl_lookup_state(host->pinctrl,
+							  "pins_uhs");
+	}
 	platform_set_drvdata(pdev, host);
 
 	ret = mmc_add_host(mmc);
-- 
2.1.4

Re: [PATCH v2 3/3] mmc: usdhi6rol0: add pinctrl to set pin drive strength

[Ulf Hansson]

On 18 April 2016 at 15:44, Lars Persson <lars.persson@axis.com> wrote:
> Some boards need different pin drive strength for the UHS mode. Add an
> optional pinctrl setting with two pin states covering UHS speeds and
> other speeds.
>
> Signed-off-by: Lars Persson <larper@axis.com>
> ---
>  drivers/mmc/host/usdhi6rol0.c | 40 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
> index 2585ea4..e8a5c8f 100644
> --- a/drivers/mmc/host/usdhi6rol0.c
> +++ b/drivers/mmc/host/usdhi6rol0.c
> @@ -22,6 +22,7 @@
>  #include <linux/mmc/sdio.h>
>  #include <linux/module.h>
>  #include <linux/pagemap.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/scatterlist.h>
>  #include <linux/string.h>
> @@ -198,6 +199,11 @@ struct usdhi6_host {
>         struct dma_chan *chan_rx;
>         struct dma_chan *chan_tx;
>         bool dma_active;
> +
> +       /* Pin control */
> +       struct pinctrl *pinctrl;
> +       struct pinctrl_state *pins_default;
> +       struct pinctrl_state *pins_uhs;
>  };
>
>  /*                     I/O primitives                                  */
> @@ -1147,14 +1153,39 @@ static void usdhi6_enable_sdio_irq(struct mmc_host *mmc, int enable)
>         }
>  }
>
> +static int usdhi6_set_pinstates(struct usdhi6_host *host, int voltage)
> +{
> +       if (IS_ERR(host->pinctrl) || IS_ERR(host->pins_default) ||
> +           IS_ERR(host->pins_uhs))

So this means, if you have UHS support you need both default and uhs
pins. That makes sense but it's not according to the DT documentation
in patch 1/3.

> +               return 0;
> +
> +       switch (voltage) {
> +       case MMC_SIGNAL_VOLTAGE_180:
> +       case MMC_SIGNAL_VOLTAGE_120:
> +               return pinctrl_select_state(host->pinctrl,
> +                                           host->pins_uhs);
> +
> +       default:
> +               return pinctrl_select_state(host->pinctrl,
> +                                           host->pins_default);
> +       }
> +}
> +
>  static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>  {
>         int ret;
>
>         ret = mmc_regulator_set_vqmmc(mmc, ios);

What if you don't have pins for default and uhs state? Should you
verify that's the case before deciding to switch voltage?

>
> -       if (ret < 0)
> +       if (ret < 0) {
>                 dev_warn(mmc_dev(mmc), "Voltage switch failed: %d\n", ret);
> +               return ret;
> +       }
> +
> +       ret = usdhi6_set_pinstates(mmc_priv(mmc), ios->signal_voltage);
> +       if (ret)
> +               dev_warn_once(mmc_dev(mmc),
> +                             "Failed to set pinstate err=%d\n", ret);
>
>         return ret;
>  }
> @@ -1817,6 +1848,13 @@ static int usdhi6_probe(struct platform_device *pdev)
>                 mmc->f_max = host->imclk;
>         mmc->f_min = host->imclk / 512;
>
> +       host->pinctrl = devm_pinctrl_get(&pdev->dev);
> +       if (!IS_ERR(host->pinctrl)) {
> +               host->pins_default = pinctrl_lookup_state(host->pinctrl,
> +                                                         PINCTRL_STATE_DEFAULT);

According to the DT documentation in patch 1/3, the default pins
should be required and not optional. I assume you want them to be
optional, but required when supporting UHS, right?

> +               host->pins_uhs     = pinctrl_lookup_state(host->pinctrl,
> +                                                         "pins_uhs");
> +       }
>         platform_set_drvdata(pdev, host);
>
>         ret = mmc_add_host(mmc);
> --
> 2.1.4
>

Kind regards
Uffe

Re: [PATCH v2 3/3] mmc: usdhi6rol0: add pinctrl to set pin drive strength

[Lars Persson]

> 19 apr. 2016 at 11:45 Ulf Hansson <ulf.hansson@linaro.org> wrote:
> 
>> On 18 April 2016 at 15:44, Lars Persson <lars.persson@axis.com> wrote:
>> Some boards need different pin drive strength for the UHS mode. Add an
>> optional pinctrl setting with two pin states covering UHS speeds and
>> other speeds.
>> 
>> Signed-off-by: Lars Persson <larper@axis.com>
>> ---
>> drivers/mmc/host/usdhi6rol0.c | 40 +++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 39 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/mmc/host/usdhi6rol0.c b/drivers/mmc/host/usdhi6rol0.c
>> index 2585ea4..e8a5c8f 100644
>> --- a/drivers/mmc/host/usdhi6rol0.c
>> +++ b/drivers/mmc/host/usdhi6rol0.c
>> @@ -22,6 +22,7 @@
>> #include <linux/mmc/sdio.h>
>> #include <linux/module.h>
>> #include <linux/pagemap.h>
>> +#include <linux/pinctrl/consumer.h>
>> #include <linux/platform_device.h>
>> #include <linux/scatterlist.h>
>> #include <linux/string.h>
>> @@ -198,6 +199,11 @@ struct usdhi6_host {
>>        struct dma_chan *chan_rx;
>>        struct dma_chan *chan_tx;
>>        bool dma_active;
>> +
>> +       /* Pin control */
>> +       struct pinctrl *pinctrl;
>> +       struct pinctrl_state *pins_default;
>> +       struct pinctrl_state *pins_uhs;
>> };
>> 
>> /*                     I/O primitives                                  */
>> @@ -1147,14 +1153,39 @@ static void usdhi6_enable_sdio_irq(struct mmc_host *mmc, int enable)
>>        }
>> }
>> 
>> +static int usdhi6_set_pinstates(struct usdhi6_host *host, int voltage)
>> +{
>> +       if (IS_ERR(host->pinctrl) || IS_ERR(host->pins_default) ||
>> +           IS_ERR(host->pins_uhs))
> 
> So this means, if you have UHS support you need both default and uhs
> pins. That makes sense but it's not according to the DT documentation
> in patch 1/3.

No. It means that if this particular board requires distinct settings for UHS then both pin states need to be defined. Otherwise we assume that the default settings are fine also for UHS.

> 
>> +               return 0;
>> +
>> +       switch (voltage) {
>> +       case MMC_SIGNAL_VOLTAGE_180:
>> +       case MMC_SIGNAL_VOLTAGE_120:
>> +               return pinctrl_select_state(host->pinctrl,
>> +                                           host->pins_uhs);
>> +
>> +       default:
>> +               return pinctrl_select_state(host->pinctrl,
>> +                                           host->pins_default);
>> +       }
>> +}
>> +
>> static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>> {
>>        int ret;
>> 
>>        ret = mmc_regulator_set_vqmmc(mmc, ios);
> 
> What if you don't have pins for default and uhs state? Should you
> verify that's the case before deciding to switch voltage

No see my reply above.

> 
>> 
>> -       if (ret < 0)
>> +       if (ret < 0) {
>>                dev_warn(mmc_dev(mmc), "Voltage switch failed: %d\n", ret);
>> +               return ret;
>> +       }
>> +
>> +       ret = usdhi6_set_pinstates(mmc_priv(mmc), ios->signal_voltage);
>> +       if (ret)
>> +               dev_warn_once(mmc_dev(mmc),
>> +                             "Failed to set pinstate err=%d\n", ret);
>> 
>>        return ret;
>> }
>> @@ -1817,6 +1848,13 @@ static int usdhi6_probe(struct platform_device *pdev)
>>                mmc->f_max = host->imclk;
>>        mmc->f_min = host->imclk / 512;
>> 
>> +       host->pinctrl = devm_pinctrl_get(&pdev->dev);
>> +       if (!IS_ERR(host->pinctrl)) {
>> +               host->pins_default = pinctrl_lookup_state(host->pinctrl,
>> +                                                         PINCTRL_STATE_DEFAULT);
> 
> According to the DT documentation in patch 1/3, the default pins
> should be required and not optional. I assume you want them to be
> optional, but required when supporting UHS, right?

Yes the default is required only when a UHS pin state is defined. Hence all the pinctrl parameters are listed as optional, but the presence of a pinctrl-names parameter makes the default pins required.

Thanks.

- Lars

Re: [PATCH v2 3/3] mmc: usdhi6rol0: add pinctrl to set pin drive strength

[Ulf Hansson]

[...]

>>>
>>> +static int usdhi6_set_pinstates(struct usdhi6_host *host, int voltage)
>>> +{
>>> +       if (IS_ERR(host->pinctrl) || IS_ERR(host->pins_default) ||
>>> +           IS_ERR(host->pins_uhs))
>>
>> So this means, if you have UHS support you need both default and uhs
>> pins. That makes sense but it's not according to the DT documentation
>> in patch 1/3.
>
> No. It means that if this particular board requires distinct settings for UHS then both pin states need to be defined. Otherwise we assume that the default settings are fine also for UHS.

I see.

I would rather see that you bail out in ->probe() when
IS_ERR(host->pinctrl) instead of testing for that here.

Conforming to the policy you describe here, you should only need to
test for IS_ERR(host->pins_uhs), as host->pins_default shall then be
implicitly covered by that test.

>
>>
>>> +               return 0;
>>> +
>>> +       switch (voltage) {
>>> +       case MMC_SIGNAL_VOLTAGE_180:
>>> +       case MMC_SIGNAL_VOLTAGE_120:
>>> +               return pinctrl_select_state(host->pinctrl,
>>> +                                           host->pins_uhs);
>>> +
>>> +       default:
>>> +               return pinctrl_select_state(host->pinctrl,
>>> +                                           host->pins_default);
>>> +       }
>>> +}
>>> +
>>> static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>>> {
>>>        int ret;
>>>
>>>        ret = mmc_regulator_set_vqmmc(mmc, ios);
>>
>> What if you don't have pins for default and uhs state? Should you
>> verify that's the case before deciding to switch voltage
>
> No see my reply above.

Okay!

>
>>
>>>
>>> -       if (ret < 0)
>>> +       if (ret < 0) {
>>>                dev_warn(mmc_dev(mmc), "Voltage switch failed: %d\n", ret);
>>> +               return ret;
>>> +       }
>>> +
>>> +       ret = usdhi6_set_pinstates(mmc_priv(mmc), ios->signal_voltage);
>>> +       if (ret)
>>> +               dev_warn_once(mmc_dev(mmc),
>>> +                             "Failed to set pinstate err=%d\n", ret);
>>>
>>>        return ret;
>>> }
>>> @@ -1817,6 +1848,13 @@ static int usdhi6_probe(struct platform_device *pdev)
>>>                mmc->f_max = host->imclk;
>>>        mmc->f_min = host->imclk / 512;
>>>
>>> +       host->pinctrl = devm_pinctrl_get(&pdev->dev);
>>> +       if (!IS_ERR(host->pinctrl)) {
>>> +               host->pins_default = pinctrl_lookup_state(host->pinctrl,
>>> +                                                         PINCTRL_STATE_DEFAULT);
>>
>> According to the DT documentation in patch 1/3, the default pins
>> should be required and not optional. I assume you want them to be
>> optional, but required when supporting UHS, right?
>
> Yes the default is required only when a UHS pin state is defined. Hence all the pinctrl parameters are listed as optional, but the presence of a pinctrl-names parameter makes the default pins required.

I am not sure why you say default state is required when pinctrl-names
is defined. It's rather a recommendation and it's being selected by
the driver core if it exist.

Please update the patch for DT documentation to reflect the policy.
Moreover you need to deploy this policy properly here and you also
need to add error handling.

In more detail.
1. Check for errors from devm_pinctrl_get() and propagate them.
2. Check if "state_uhs" can be fetched and if so try also to fetch
default state. If the latter fails you need propagate that as an error
as well.

Does that make sense?

Kind regards
Uffe

Re: [PATCH v2 3/3] mmc: usdhi6rol0: add pinctrl to set pin drive strength

[Lars Persson]

On 04/20/2016 02:15 PM, Ulf Hansson wrote:
> [...]
>
>>>>
>>>> +static int usdhi6_set_pinstates(struct usdhi6_host *host, int voltage)
>>>> +{
>>>> +       if (IS_ERR(host->pinctrl) || IS_ERR(host->pins_default) ||
>>>> +           IS_ERR(host->pins_uhs))
>>>
>>> So this means, if you have UHS support you need both default and uhs
>>> pins. That makes sense but it's not according to the DT documentation
>>> in patch 1/3.
>>
>> No. It means that if this particular board requires distinct settings for UHS then both pin states need to be defined. Otherwise we assume that the default settings are fine also for UHS.
>
> I see.
>
> I would rather see that you bail out in ->probe() when
> IS_ERR(host->pinctrl) instead of testing for that here.
>
> Conforming to the policy you describe here, you should only need to
> test for IS_ERR(host->pins_uhs), as host->pins_default shall then be
> implicitly covered by that test.

Ok.

>
>>
>>>
>>>> +               return 0;
>>>> +
>>>> +       switch (voltage) {
>>>> +       case MMC_SIGNAL_VOLTAGE_180:
>>>> +       case MMC_SIGNAL_VOLTAGE_120:
>>>> +               return pinctrl_select_state(host->pinctrl,
>>>> +                                           host->pins_uhs);
>>>> +
>>>> +       default:
>>>> +               return pinctrl_select_state(host->pinctrl,
>>>> +                                           host->pins_default);
>>>> +       }
>>>> +}
>>>> +
>>>> static int usdhi6_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>>>> {
>>>>         int ret;
>>>>
>>>>         ret = mmc_regulator_set_vqmmc(mmc, ios);
>>>
>>> What if you don't have pins for default and uhs state? Should you
>>> verify that's the case before deciding to switch voltage
>>
>> No see my reply above.
>
> Okay!
>
>>
>>>
>>>>
>>>> -       if (ret < 0)
>>>> +       if (ret < 0) {
>>>>                 dev_warn(mmc_dev(mmc), "Voltage switch failed: %d\n", ret);
>>>> +               return ret;
>>>> +       }
>>>> +
>>>> +       ret = usdhi6_set_pinstates(mmc_priv(mmc), ios->signal_voltage);
>>>> +       if (ret)
>>>> +               dev_warn_once(mmc_dev(mmc),
>>>> +                             "Failed to set pinstate err=%d\n", ret);
>>>>
>>>>         return ret;
>>>> }
>>>> @@ -1817,6 +1848,13 @@ static int usdhi6_probe(struct platform_device *pdev)
>>>>                 mmc->f_max = host->imclk;
>>>>         mmc->f_min = host->imclk / 512;
>>>>
>>>> +       host->pinctrl = devm_pinctrl_get(&pdev->dev);
>>>> +       if (!IS_ERR(host->pinctrl)) {
>>>> +               host->pins_default = pinctrl_lookup_state(host->pinctrl,
>>>> +                                                         PINCTRL_STATE_DEFAULT);
>>>
>>> According to the DT documentation in patch 1/3, the default pins
>>> should be required and not optional. I assume you want them to be
>>> optional, but required when supporting UHS, right?
>>
>> Yes the default is required only when a UHS pin state is defined. Hence all the pinctrl parameters are listed as optional, but the presence of a pinctrl-names parameter makes the default pins required.
>
> I am not sure why you say default state is required when pinctrl-names
> is defined. It's rather a recommendation and it's being selected by
> the driver core if it exist.

I considered the two use-cases for pinctrl in this driver:
- Only using default and letting the core select it.
- Using it for UHS in which case default and pins_uhs are required.

Both cases need the default, that is why it was listed as required. But 
I will change this based on your feedback.

>
> Please update the patch for DT documentation to reflect the policy.
> Moreover you need to deploy this policy properly here and you also
> need to add error handling.
>
> In more detail.
> 1. Check for errors from devm_pinctrl_get() and propagate them.
> 2. Check if "state_uhs" can be fetched and if so try also to fetch
> default state. If the latter fails you need propagate that as an error
> as well.
>
> Does that make sense?

OK, I will implement this error checking.

- Lars

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