RE: [PATCH v1] mmc: rtsx_usb_sdmmc: add parameter to always poll for card presence

[Ricky WU <ricky_wu@realtek.com>]

> On Sat, 24 May 2025 at 05:37, Gavin Li <gfl3162@gmail.com> wrote:
> >
> > On Mon, May 19, 2025 at 7:50 AM Ulf Hansson <ulf.hansson@linaro.org>
> wrote:
> >
> > > Moving this problem to userspace seems wrong to me. We should be
> > > able to do the right thing in the kernel.
> >
> > Unfortunately, I don't have access to the datasheet for the RTS5179 or
> > related chips. This is what I could do to get my own hardware working,
> > and it doesn't make sense to revert to polling mode for all users if
> > the interrupt mode detection works and reduces power consumption.
> 
> Agree!
> 
> >
> > > We should be able to detect if we are running the broken HW and in
> > > that case, set the flag based on that, right?
> >
> > I don't know of a way to do so, especially since I don't have
> > non-broken HW in my possession. On my hardware, once the device enters
> > autosuspend, inserting a card does not trigger a wakeup. I'm hoping
> > that there's a way to detect the broken HW via a hardware revision register
> or something similar.
> 
> Yes, something along those lines would make sense. Let's see if Ricky can
> advise us on how to move forward.
> 

Hi Gavin,

I’m not entirely clear on what the actual issue is at this point. Initially, there was mention of “some RTS5179…” and later, 
“broken hardware…” was brought up.
Could you please clarify — is this problem happening only on certain platforms? Or is it something else?

HI Uif,

Is it generally true? That devices using the MMC_CAP_NEEDS_POLL flag may not fully support runtime_suspend,
Since they rely on polling rather than interrupts.
This can prevent the decices or host controller from reaching deeper power-saving states.


> Kind regards
> Uffe