linux-kernel - Re: [PATCH] misc: rtsx: usb: Ensure mmc child device is active when card is present

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Message-ID: <CA+GxvY4x99MO-bd4s_ZRq54-+ELZ7UVPTFK0Fk=H1pnEGkPyxQ@mail.gmail.com>
Date: Sun, 20 Jul 2025 22:33:56 -0400
From: Gavin Li <gfl3162@...il.com>
To: Ulf Hansson <ulf.hansson@...aro.org>
Cc: Ricky Wu <ricky_wu@...ltek.com>, linux-kernel@...r.kernel.org, arnd@...db.de, 
	gregkh@...uxfoundation.org, mingo@...nel.org, kai.heng.feng@...onical.com, 
	stable@...r.kernel.org
Subject: Re: [PATCH] misc: rtsx: usb: Ensure mmc child device is active when
 card is present

I just tested out this patch, and it unfortunately does not address
the issue I was running into (where the driver fails to detect
inserting a SD card after the initial driver probe).

On Wed, Jul 16, 2025 at 6:39 AM Ulf Hansson <ulf.hansson@...aro.org> wrote:
>
> + Gavin
>
> On Fri, 11 Jul 2025 at 16:02, Ricky Wu <ricky_wu@...ltek.com> wrote:
> >
> > When a card is present in the reader, the driver currently defers
> > autosuspend by returning -EAGAIN during the suspend callback to
> > trigger USB remote wakeup signaling. However, this does not guarantee
> > that the mmc child device has been resumed, which may cause issues if
> > it remains suspended while the card is accessible.
> > This patch ensures that all child devices, including the mmc host
> > controller, are explicitly resumed before returning -EAGAIN. This
> > fixes a corner case introduced by earlier remote wakeup handling,
> > improving reliability of runtime PM when a card is inserted.
> >
> > Fixes: 883a87ddf2f1 ("misc: rtsx_usb: Use USB remote wakeup signaling for card insertion detection")
> > Cc: stable@...r.kernel.org
> > Signed-off-by: Ricky Wu <ricky_wu@...ltek.com>
>
> This seems reasonable to me, but perhaps some of the USB maintainers
> should have a closer look to see if this makes sense. Nevertheless,
> feel free to add:
>
> Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
>
> Moreover, we had a related bug-report/fix posted for the
> rtsx_usb_sdmmc driver [1] not that long ago. Do you know if $subject
> patch solves this problem too? I have looped in Gavin, if he has some
> additional comments around this.
>
> Kind regards
> Uffe
>
> [1]
> https://lore.kernel.org/all/20250510031945.1004129-1-git@thegavinli.com/
>
> > ---
> >  drivers/misc/cardreader/rtsx_usb.c | 16 +++++++++-------
> >  1 file changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/misc/cardreader/rtsx_usb.c b/drivers/misc/cardreader/rtsx_usb.c
> > index 148107a4547c..d007a4455ce5 100644
> > --- a/drivers/misc/cardreader/rtsx_usb.c
> > +++ b/drivers/misc/cardreader/rtsx_usb.c
> > @@ -698,6 +698,12 @@ static void rtsx_usb_disconnect(struct usb_interface *intf)
> >  }
> >
> >  #ifdef CONFIG_PM
> > +static int rtsx_usb_resume_child(struct device *dev, void *data)
> > +{
> > +       pm_request_resume(dev);
> > +       return 0;
> > +}
> > +
> >  static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
> >  {
> >         struct rtsx_ucr *ucr =
> > @@ -713,8 +719,10 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
> >                         mutex_unlock(&ucr->dev_mutex);
> >
> >                         /* Defer the autosuspend if card exists */
> > -                       if (val & (SD_CD | MS_CD))
> > +                       if (val & (SD_CD | MS_CD)) {
> > +                               device_for_each_child(&intf->dev, NULL, rtsx_usb_resume_child);
> >                                 return -EAGAIN;
> > +                       }
> >                 } else {
> >                         /* There is an ongoing operation*/
> >                         return -EAGAIN;
> > @@ -724,12 +732,6 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
> >         return 0;
> >  }
> >
> > -static int rtsx_usb_resume_child(struct device *dev, void *data)
> > -{
> > -       pm_request_resume(dev);
> > -       return 0;
> > -}
> > -
> >  static int rtsx_usb_resume(struct usb_interface *intf)
> >  {
> >         device_for_each_child(&intf->dev, NULL, rtsx_usb_resume_child);
> > --
> > 2.25.1
> >