RE: [PATCH 3/3] mmc: omap_hsmmc: enable SDIO card interrupts

["Madhusudhan" <madhu.cr@ti.com>]

> -----Original Message-----
> From: David Vrabel [mailto:david.vrabel@csr.com]
> Sent: Wednesday, February 17, 2010 1:40 PM
> To: Madhusudhan
> Cc: linux-mmc@vger.kernel.org; linux-omap@vger.kernel.org
> Subject: Re: [PATCH 3/3] mmc: omap_hsmmc: enable SDIO card interrupts
> 
> Madhusudhan wrote:
> >
> >> -----Original Message-----
> >> From: David Vrabel [mailto:david.vrabel@csr.com]
> >> Sent: Wednesday, February 10, 2010 5:52 AM
> >> To: linux-mmc@vger.kernel.org
> >> Cc: David Vrabel; linux-omap@vger.kernel.org; madhu.cr@ti.com
> >> Subject: [PATCH 3/3] mmc: omap_hsmmc: enable SDIO card interrupts
> >>
> >> Enable the use of SDIO card interrupts.  This requires setting
> ENAWAKEUP
> >> in SYSCONFIG and IWE in HTCL to allow the MMC block to wake-up when in
> >> smart-idle mode.
> >>
> >> FCLK must be enabled while SDIO interrupts are enabled or the MMC block
> >> won't wake-up.
> >>
> >
> > I am curious to know the system behavior with this patch. Does the FCLK
> > remain enabled forever if a SDIO card is detected on the bus?
> 
> Only if card interrupts are enabled.  The card irq is disabled when the
> sdio_irq_thread exits.
> 

Your patch sets up the capability to enable sdio irqs anyway. My question
was more related to the idle path. In a scenario where you start using the
SDIO functionality and after some time you leave the SDIO card idle, does
the FCLK still remain enabled? Or do you see that sdio_irq_thread exits and
disables the FCLK?

Regards,
Madhu


> This is why I think that smart-idle mode needs to be used (it's turned
> on by default on the MMC controller) but I don't understand the
> clock/clockdomain code to see if that's doing the right thing.
> 
> If smart-idle mode is used then we don't need to disable FCLK manually
> to save power.  This will simplify the driver a bit.
> 
> David