linux-kernel - Re: [RFC PATCH] mmc: sdhci-of-at91: don't put device in suspend after probe

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Message-ID: <20160210125139.GB14937@odux.rfo.atmel.com>
Date:	Wed, 10 Feb 2016 13:51:39 +0100
From:	Ludovic Desroches <ludovic.desroches@...el.com>
To:	Adrian Hunter <adrian.hunter@...el.com>
CC:	Ludovic Desroches <ludovic.desroches@...el.com>,
	<ulf.hansson@...aro.org>, <linux-mmc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <nicolas.ferre@...el.com>
Subject: Re: [RFC PATCH] mmc: sdhci-of-at91: don't put device in suspend
 after probe

Hi Adrian,

On Wed, Feb 10, 2016 at 01:50:44PM +0200, Adrian Hunter wrote:
> On 10/02/16 11:58, Ludovic Desroches wrote:
> > By putting the device in suspend at the end of the probe, it is
> > impossible to wake up on non software event such as card
> > insertion/removal.
> > 
> > Signed-off-by: Ludovic Desroches <ludovic.desroches@...el.com>
> > ---
> > 
> > Hi,
> > 
> > Since I had no feedback on this topic:
> > http://permalink.gmane.org/gmane.linux.kernel.mmc/35160
> > 
> > I would like to no more put the device in suspend at the end of the probe. If
> > my device is suspended at the end of the probe, I have no issue to resume on
> > a software event such as mounting my sdcard but hardware event such as card
> > insertion and removal do not trigger a resume.
> 
> You can't use runtime PM unless you have a way to wake-up.
> 

Thanks for your feedback. I am a bit disappointed since Ulf advised me to use
runtime PM instead of system PM.

> Currently, sdhci disables card detect interrupts when runtime suspended,
> and drivers use a card-detect GPIO to wake-up.
> 

It is what I have seen going through the sdhci layer. So next question is:
is it normal to not take care of card detect interrupts? We keep enabled
some IRQs probably for SDIO modules IRQ but not for card detection. I
don't understand the reason.

> 
> > 
> > It seems there are only two sdhci drivers using runtime pm so maybe nobody has
> > noticed this issue.
> > 
> > Regards
> > 
> > Ludovic
> > 
> >  drivers/mmc/host/sdhci-of-at91.c | 2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> > index 9cb86fb..ae24dea 100644
> > --- a/drivers/mmc/host/sdhci-of-at91.c
> > +++ b/drivers/mmc/host/sdhci-of-at91.c
> > @@ -210,8 +210,6 @@ static int sdhci_at91_probe(struct platform_device *pdev)
> >  	if (ret)
> >  		goto pm_runtime_disable;
> >  
> > -	pm_runtime_put_autosuspend(&pdev->dev);
> > -
> >  	return 0;
> >  
> >  pm_runtime_disable:
> > 
>