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

[Iker Pedrosa]

El mar, 17 mar 2026 a las 12:28, Adrian Hunter
(<adrian.hunter@xxxxxxxxx>) 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@xxxxxxxxx>
> > Signed-off-by: Iker Pedrosa <ikerpedrosam@xxxxxxxxx>
> > ---
> >  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@xxxxxxxxx/

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? 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;
> >
>