Re: [PATCH v3 2/7] mmc: sdhci-of-k1: add regulator and pinctrl voltage switching support

[Adrian Hunter <adrian.hunter@intel.com>]

On 20/03/2026 11:17, Iker Pedrosa wrote:
> El mar, 17 mar 2026 a las 12:28, Adrian Hunter
> (<adrian.hunter@intel.com>) escribió:
>>
>> On 16/03/2026 16:03, Iker Pedrosa wrote:
>>> Add voltage switching infrastructure for UHS-I modes by integrating both
>>> regulator framework (for supply voltage control) and pinctrl state
>>> switching (for pin drive strength optimization).
>>>
>>> - Add regulator supply parsing and voltage switching callback
>>> - Add optional pinctrl state switching between "default" (3.3V) and
>>>   "state_uhs" (1.8V) configurations
>>> - Enable coordinated voltage and pin configuration changes for UHS modes
>>>
>>> This provides complete voltage switching support while maintaining
>>> backward compatibility when pinctrl states are not defined.
>>>
>>> Tested-by: Anand Moon <linux.amoon@gmail.com>
>>> Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
>>> ---
>>>  drivers/mmc/host/sdhci-of-k1.c | 58 ++++++++++++++++++++++++++++++++++++++++++
>>>  1 file changed, 58 insertions(+)
>>>
>>> diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c
>>> index 0dd06fc19b8574ae1b00f7e5d09b7d4c87d06770..01afdadcf70796704b272ee5a31543afd5e01188 100644
>>> --- a/drivers/mmc/host/sdhci-of-k1.c
>>> +++ b/drivers/mmc/host/sdhci-of-k1.c
>>> @@ -16,6 +16,7 @@
>>>  #include <linux/of.h>
>>>  #include <linux/of_device.h>
>>>  #include <linux/reset.h>
>>> +#include <linux/pinctrl/consumer.h>
>>>  #include <linux/platform_device.h>
>>>
>>>  #include "sdhci.h"
>>> @@ -71,6 +72,9 @@
>>>  struct spacemit_sdhci_host {
>>>       struct clk *clk_core;
>>>       struct clk *clk_io;
>>> +     struct pinctrl *pinctrl;
>>> +     struct pinctrl_state *pinctrl_default;
>>> +     struct pinctrl_state *pinctrl_uhs;
>>>  };
>>>
>>>  /* All helper functions will update clr/set while preserve rest bits */
>>> @@ -219,6 +223,33 @@ static void spacemit_sdhci_pre_hs400_to_hs200(struct mmc_host *mmc)
>>>                              SPACEMIT_SDHC_PHY_CTRL_REG);
>>>  }
>>>
>>> +static void spacemit_sdhci_voltage_switch(struct sdhci_host *host)
>>> +{
>>> +     struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>> +     struct spacemit_sdhci_host *sdhst = sdhci_pltfm_priv(pltfm_host);
>>> +     struct mmc_ios *ios = &host->mmc->ios;
>>> +     int ret;
>>> +
>>> +     if (!sdhst->pinctrl)
>>> +             return;
>>> +
>>> +     if (ios->signal_voltage != MMC_SIGNAL_VOLTAGE_180) {
>>> +             dev_warn(mmc_dev(host->mmc), "unsupported voltage %d\n",
>>> +                      ios->signal_voltage);
>>> +             return;
>>> +     }
>>
>> In V2, I put "->voltage_switch() is called only for
>> ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180" by
>> which I meant that it does not allow the driver to
>> switch pin state back for 3.3V.
>>
>> So you probably need an approach similar to the original
>> spacemit_sdhci_start_signal_voltage_switch() in:
>>
>>         https://lore.kernel.org/linux-mmc/20260302-orangepi-sd-card-uhs-v1-4-89c219973c0c@gmail.com/
> 
> Thank you for the feedback. I want to make sure I understand this
> point correctly to avoid going in circles.
> 
> In the v2 feedback , you mentioned that "->voltage_switch() is called
> only for ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180", which I
> understood to mean that this callback only needs to handle switching
> to 1.8V. This meant that the changes I introduced for v3 don't manage
> the switching to 3.3V.
> 
> Can you clarify if I should I revert to implementing
> "->start_signal_voltage_switch()" instead, which would handle both
> 1.8V and 3.3V cases? 

Yes

Or is there a way to make the
> "->voltage_switch()" approach work properly for both directions?
> 
>>
>>> +
>>> +     if (sdhst->pinctrl_uhs) {
>>> +             ret = pinctrl_select_state(sdhst->pinctrl, sdhst->pinctrl_uhs);
>>> +             if (ret) {
>>> +                     dev_warn(mmc_dev(host->mmc),
>>> +                              "failed to select UHS pinctrl state: %d\n", ret);
>>> +                     return;
>>> +             }
>>> +             dev_dbg(mmc_dev(host->mmc), "switched to UHS pinctrl state\n");
>>> +     }
>>> +}
>>> +
>>>  static inline int spacemit_sdhci_get_clocks(struct device *dev,
>>>                                           struct sdhci_pltfm_host *pltfm_host)
>>>  {
>>> @@ -252,12 +283,37 @@ static inline int spacemit_sdhci_get_resets(struct device *dev)
>>>       return 0;
>>>  }
>>>
>>> +static inline void spacemit_sdhci_get_pins(struct device *dev,
>>> +                                         struct sdhci_pltfm_host *pltfm_host)
>>> +{
>>> +     struct spacemit_sdhci_host *sdhst = sdhci_pltfm_priv(pltfm_host);
>>> +
>>> +     sdhst->pinctrl = devm_pinctrl_get(dev);
>>> +     if (IS_ERR(sdhst->pinctrl)) {
>>> +             sdhst->pinctrl = NULL;
>>> +             dev_dbg(dev, "pinctrl not available, voltage switching will work without it\n");
>>> +             return;
>>> +     }
>>> +
>>> +     sdhst->pinctrl_default = pinctrl_lookup_state(sdhst->pinctrl, "default");
>>> +     if (IS_ERR(sdhst->pinctrl_default))
>>> +             sdhst->pinctrl_default = NULL;
>>> +
>>> +     sdhst->pinctrl_uhs = pinctrl_lookup_state(sdhst->pinctrl, "state_uhs");
>>> +     if (IS_ERR(sdhst->pinctrl_uhs))
>>> +             sdhst->pinctrl_uhs = NULL;
>>> +
>>> +     dev_dbg(dev, "pinctrl setup: default=%p, uhs=%p\n",
>>> +             sdhst->pinctrl_default, sdhst->pinctrl_uhs);
>>> +}
>>> +
>>>  static const struct sdhci_ops spacemit_sdhci_ops = {
>>>       .get_max_clock          = spacemit_sdhci_clk_get_max_clock,
>>>       .reset                  = spacemit_sdhci_reset,
>>>       .set_bus_width          = sdhci_set_bus_width,
>>>       .set_clock              = spacemit_sdhci_set_clock,
>>>       .set_uhs_signaling      = spacemit_sdhci_set_uhs_signaling,
>>> +     .voltage_switch         = spacemit_sdhci_voltage_switch,
>>>  };
>>>
>>>  static const struct sdhci_pltfm_data spacemit_sdhci_k1_pdata = {
>>> @@ -324,6 +380,8 @@ static int spacemit_sdhci_probe(struct platform_device *pdev)
>>>
>>>       host->mmc->caps |= MMC_CAP_NEED_RSP_BUSY;
>>>
>>> +     spacemit_sdhci_get_pins(dev, pltfm_host);
>>> +
>>>       ret = spacemit_sdhci_get_clocks(dev, pltfm_host);
>>>       if (ret)
>>>               goto err_pltfm;
>>>
>>