sdhci: runtime suspend/resume on card insert/removal

[Russell King - ARM Linux]

On Thu, Sep 10, 2015 at 03:31:29PM +0800, Jisheng Zhang wrote:
> Hi Vaibhav,
> 
> On Thu, 10 Sep 2015 12:40:48 +0530
> Vaibhav Hiremath <vaibhav.hiremath at linaro.org> wrote:
> 
> > Hi,
> > 
> > During my testing of SDHCI-PXAV3 driver on Marvell's pxa1928
> > based platform, I observed that runtime PM suspend/resume is having
> > issues with card insertion and removal.
> > 
> > Let me try to explain it using execution sequence -
> > 
> > During boot:
> > 
> > MMC SD card gets detected as expected.
> > 
> > [    2.431012] mmc1: new high speed SDHC card at address 1234
> > [    2.437235] mmcblk1: mmc1:1234 SA04G 3.63 GiB
> > [    2.444841]  mmcblk1: p1
> > 
> > 
> > Now after coming to the linux prompt, if card removal event occurs
> > then the call sequence is -
> > 
> >   sdhci_irq() -->
> >    -> sdhci_thread_irq(): host->thread_isr - 0x80
> >       -> sdhci_card_event()
> >       -> mmc_detect_change()
> >          --> _mmc_detect_change()
> >              --->  mmc_sd_detect()
> >                    mmc_sd_remove()
> >                    mmc_remove_card()
> >                    mmc_bus_remove()
> >                    mmc_power_off()
> >                    mmc_set_initial_state()
> >                    sdhci_set_ios()
> >                    ...
> >         sdhci_pxav3_runtime_suspend()
> >         sdhci_runtime_suspend_host()
> > 
> > 
> > Till here everything looks perfect :) (if I got it right)
> > 
> > Now on card insertion again, the expectation is, runtime resume should
> > get called as part of interrupt trigger from the SDHCI controller on
> > card insertion.
> 
> AFAIK, card insertion => wakeup irq, this irq doesn't come from SDHCI

Wakeup IRQs are what happens when the _system_ is in suspend, not
when the device is runtime suspended.

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