Re: [PATCH] mmc: change mmc_gpio_get_cd to call non-sleep gpio

[Christian Daudt]

On 13-08-08 02:10 PM, Christian Daudt wrote:
> On 13-08-08 02:06 PM, Guennadi Liakhovetski wrote:
> > On Thu, 8 Aug 2013, Christian Daudt wrote:
> >
> > > Given that mmc_gpio_get_cd can be called in softirq
> > > context (by sdhci_tasklet_card -> sdhci_card_event ->
> > > sdhci_do_get_cd -> mmc_gpio_get_cd ), it is necessary
> > > for it to use gpio_get_value instead of
> > > gpio_get_value_cansleep
> > > Note that at present sdhci_card_event gets called both
> > > from mmc_gpio_cd_irqt and sdhci_tasklet_card, and from
> > > both it gets called immediately while the actual cd
> > > processing is debounced to 200ms later. I think that
> > > the better solution might be to move the sdhci_card_event
> > > callback into mmc_rescan and remove it from its 2
> > > present locations. That way the cd related callbacks
> > > are aligned with the actual cd detection code. I can
> > > submit a follow-up patch with these mods if that sounds
> > > like a better way to solve this.
> > >
> > > Signed-off-by: Christian Daudt <csd@xxxxxxxxxxxx>
> > I don't think this is a right approach. It will Oops if the card-detect
> > GPIO is provided by, e.g. an I2C GPIO controller. Instead the driver
> > should be fixed to only call this function from a sleeping context.
> I don't think that card-detect would ever be tied to i2c but I might 
> be wrong on that one... If there's agreement that moving 
> sdhci_card_event into just being called from mmc_rescan is the better 
> way to solve this, then I'll drop this patch and replace it with one 
> that does just that.
>
>  Thanks,
>    csd
[adding arm@xxxxxxxxxx for more input]
Guennadi,
 While I can't see card-detect coming in through i2c gpio controller, I 
think that moving this out of the sleeping context (and into mmc_rescan) 
is probably the better solution anyways. So I'll drop this patch and 
send another one with that change instead.


 Thanks,
   csd


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