Re: [PATCH v3 2/3] mmc: Add realtek USB sdmmc host driver

[Roger]

On 02/11/2014 05:50 PM, Ulf Hansson wrote:
> On 11 February 2014 10:27, Roger <rogerable@xxxxxxxxxxx> wrote:
> > On 02/10/2014 10:58 PM, Ulf Hansson wrote:
> > > On 6 February 2014 15:35,  <rogerable@xxxxxxxxxxx> wrote:
> > > > From: Roger Tseng <rogerable@xxxxxxxxxxx>
> > > >
> > > > Realtek USB SD/MMC host driver provides mmc host support based on the
> > > > Realtek
> > > > USB card reader MFD driver.
> > > >
> > > > Signed-off-by: Roger Tseng <rogerable@xxxxxxxxxxx>
> > > > ---
> > > >    drivers/mmc/host/Kconfig          |    7 +
> > > >    drivers/mmc/host/Makefile         |    1 +
> > > >    drivers/mmc/host/rtsx_usb_sdmmc.c | 1500
> > > > +++++++++++++++++++++++++++++++++++++
> > > >    3 files changed, 1508 insertions(+)
> > > >    create mode 100644 drivers/mmc/host/rtsx_usb_sdmmc.c
> >
> > [snip]
> >
> > > > +#ifdef CONFIG_PM_RUNTIME
> > >
> > >
> > > There are stubs for pm_runtime* functions, thus the ifdefs can be removed.
> > > Please go though the complete patch and remove all instances.
> > >
> > > > +               pm_runtime_put(sdmmc_dev(host));
> > >
> > >
> > > I don't know so much about USB mmc hosts hardware, but I just wanted
> > > to find out if I have understood this correct.
> > >
> > > You can't do fine grained power management of the USB parent device,
> > > since it needs to be runtime resumed to be able keep the power the
> > > card? Once it becomes runtime suspended, the power to the card will
> > > thus also be dropped?
> > Yes, and to keep some internal state of the controller.
>
> Okay.
>
> But the internal state of the controller should be possible to restore
> at runtime_resume, so that should not be the reason, right?

I checked again. Internal registers will hold its state during suspend.
Card power is the exact reason.
> > > Kind regards
> > > Ulf Hansson
> .
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