Re: [PATCH v13 3/3] mmc: mediatek: add support for SDIO eint wakup IRQ

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+ Linus Walleij

On Tue, 19 Jul 2022 at 12:35, Axe Yang <axe.yang@xxxxxxxxxxxx> wrote:
>
> On Mon, 2022-07-18 at 14:21 +0200, Ulf Hansson wrote:
> > On Thu, 23 Jun 2022 at 11:05, Axe Yang <axe.yang@xxxxxxxxxxxx> wrote:
> > >
> > > Add support for eint IRQ when MSDC is used as an SDIO host. This
> > > feature requires SDIO device support async IRQ function. With this
> > > feature, SDIO host can be awakened by SDIO card in suspend state,
> > > without additional pin.
> > >
> > > MSDC driver will time-share the SDIO DAT1 pin. During suspend, MSDC
> > > turn off clock and switch SDIO DAT1 pin to GPIO mode. And during
> > > resume, switch GPIO function back to DAT1 mode then turn on clock.
> > >
> > > Some device tree property should be added or modified in MSDC node
> > > to support SDIO eint IRQ. Pinctrls "state_eint" is mandatory. Since
> > > this feature depends on asynchronous interrupts, "wakeup-source",
> > > "keep-power-in-suspend" and "cap-sdio-irq" flags are necessary, and
> > > the interrupts list should be extended(the interrupt named with
> > > sdio_wakeup):
> > >         &mmcX {
> > >                 ...
> > >                 interrupt-names = "msdc", "sdio_wakeup";
> > >                 interrupts-extended = <...>,
> > >                                       <&pio xxx
> > > IRQ_TYPE_LEVEL_LOW>;
> > >                 ...
> > >                 pinctrl-names = "default", "state_uhs",
> > > "state_eint";
> > >                 ...
> > >                 pinctrl-2 = <&mmc2_pins_eint>;
> > >                 ...
> > >                 cap-sdio-irq;
> > >                 keep-power-in-suspend;
> > >                 wakeup-source;
> > >                 ...
> > >         };
> > >
> > > Co-developed-by: Yong Mao <yong.mao@xxxxxxxxxxxx>
> > > Signed-off-by: Yong Mao <yong.mao@xxxxxxxxxxxx>
> > > Signed-off-by: Axe Yang <axe.yang@xxxxxxxxxxxx>
> >
> > My apologies for the delay in reviewing this.
>
> It is okay. Glad to receive your reply.
>
> >
> > > ---
> > >  drivers/mmc/host/mtk-sd.c | 84
> > > ++++++++++++++++++++++++++++++++++++---
> > >  1 file changed, 78 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> > > index 195dc897188b..f907b96cfd87 100644
> > > --- a/drivers/mmc/host/mtk-sd.c
> > > +++ b/drivers/mmc/host/mtk-sd.c
> > > @@ -1,6 +1,6 @@
> > >  // SPDX-License-Identifier: GPL-2.0-only
> > >  /*
> > > - * Copyright (c) 2014-2015 MediaTek Inc.
> > > + * Copyright (c) 2014-2015, 2022 MediaTek Inc.
> > >   * Author: Chaotian.Jing <chaotian.jing@xxxxxxxxxxxx>
> > >   */
> > >
> > > @@ -20,6 +20,7 @@
> > >  #include <linux/platform_device.h>
> > >  #include <linux/pm.h>
> > >  #include <linux/pm_runtime.h>
> > > +#include <linux/pm_wakeirq.h>
> > >  #include <linux/regulator/consumer.h>
> > >  #include <linux/slab.h>
> > >  #include <linux/spinlock.h>
> > > @@ -440,8 +441,10 @@ struct msdc_host {
> > >         struct pinctrl *pinctrl;
> > >         struct pinctrl_state *pins_default;
> > >         struct pinctrl_state *pins_uhs;
> > > +       struct pinctrl_state *pins_eint;
> > >         struct delayed_work req_timeout;
> > >         int irq;                /* host interrupt */
> > > +       int eint_irq;           /* interrupt from sdio device for
> > > waking up system */
> > >         struct reset_control *reset;
> > >
> > >         struct clk *src_clk;    /* msdc source clock */
> > > @@ -1520,17 +1523,46 @@ static void __msdc_enable_sdio_irq(struct
> > > msdc_host *host, int enb)
> > >
> > >  static void msdc_enable_sdio_irq(struct mmc_host *mmc, int enb)
> > >  {
> > > -       unsigned long flags;
> > >         struct msdc_host *host = mmc_priv(mmc);
> > > +       unsigned long flags;
> > > +       int ret;
> > >
> > >         spin_lock_irqsave(&host->lock, flags);
> > >         __msdc_enable_sdio_irq(host, enb);
> > >         spin_unlock_irqrestore(&host->lock, flags);
> > >
> > > -       if (enb)
> > > -               pm_runtime_get_noresume(host->dev);
> > > -       else
> > > -               pm_runtime_put_noidle(host->dev);
> > > +       if (mmc_card_enable_async_irq(mmc->card) && host-
> > > >pins_eint) {
> > > +               if (enb) {
> > > +                       /*
> > > +                        * In
> > > dev_pm_set_dedicated_wake_irq_reverse(), eint pin will be set to
> > > +                        * GPIO mode. We need to restore it to SDIO
> > > DAT1 mode after that.
> > > +                        * Since the current pinstate is pins_uhs,
> > > to ensure pinctrl select take
> > > +                        * affect successfully, we change the
> > > pinstate to pins_eint firstly.
> > > +                        */
> > > +                       pinctrl_select_state(host->pinctrl, host-
> > > >pins_eint);
> >
> > I am sorry, but I don't understand what goes on here. Why do you need
> > to change the pinctrl setting to "pins_eint" here?
> >
> > The bellow call to dev_pm_set_dedicated_wake_irq_reverse() doesn't
> > change the pinctrl setting as the comment suggests above.
> >
>
> Actually, the pinctrl setting is changed:
> In dev_pm_set_dedicated_wake_irq_reverse() -> ... ->
> request_threaded_irq() -> __setup_irq() -> irq_request_resources() ->
> mtk_eint_irq_request_resources()-> mtk_xt_set_gpio_as_eint(), the SDIO
> DAT1 pin will be force reset to GPIO mode:

Aha. That looks a bit weird, but I get the problem now.

I have looped in Linus (the pintctrl maintainer) to get his opinion on this.

>
> https://elixir.bootlin.com/linux/latest/source/drivers/pinctrl/mediatek/pinctrl-mtk-common-v2.c#L339
>
> So, I have to call pinctrl_select_state() to restore SDIO DAT1 pin
> mode(pins_uhs). But pinctrl_select_state() return directly because MSDC
> driver still wrongly thinks current DAT1 state is SDIO DAT1 mode:
>
> https://elixir.bootlin.com/linux/latest/source/drivers/pinctrl/core.c#L1344
> , which means I have to call pinctrl_select_state() in pairs: Change
> pinctrl to another state(pins_eint), then change it back to pins_uhs
> mode.

I see. So a call to pinctrl_select_state("pins_uhs") would not take
effect, unless we call pinctrl_select_state("pins_eint") first. That
sounds like the internal state of the pinctrl isn't maintained
properly.

Let's see what Linus thinks about this.

Note that, I am happy to pick the patch as is around this, but I am
worried we might be doing something at the mmc driver level, which
should really be managed at the pinctrl layer.

>
>
> > dev_pm_set_dedicated_wake_irq_reverse() will register the wakeirq,
> > but
> > more importantly, it should also leave the wakeirq disabled, right?
>
> Yes. wakeirq will be registered, and disabled. But SDIO DAT1 pin mode
> will be changed too.
>
> >
> > > +                       ret =
> > > dev_pm_set_dedicated_wake_irq_reverse(host->dev, host->eint_irq);
> > > +
> > > +                       if (ret) {
> > > +                               dev_err(host->dev, "Failed to
> > > register SDIO wakeup irq!\n");
> > > +                               host->pins_eint = NULL;
> > > +                               pm_runtime_get_noresume(host->dev);
> > > +                       } else {
> > > +                               dev_dbg(host->dev, "SDIO eint irq:
> > > %d!\n", host->eint_irq);
> > > +                       }
> > > +
> > > +                       pinctrl_select_state(host->pinctrl, host-
> > > >pins_uhs);
> >
> > According to my comment above, I also don't understand why you need
> > this. Why can't you just leave the pinctrl in the "pins_uhs" state?
> >
> I have to call pinctrl_select_state() in pairs.
>
>
> > > +               } else {
> > > +                       dev_pm_clear_wake_irq(host->dev);
> > > +               }
> > > +       } else {
> > > +               if (enb) {
> > > +                       /* Ensure host->pins_eint is NULL */
> > > +                       host->pins_eint = NULL;
> > > +                       pm_runtime_get_noresume(host->dev);
> > > +               } else {
> > > +                       pm_runtime_put_noidle(host->dev);
> > > +               }
> > > +       }
> > >  }

[...]

Kind regards
Uffe



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