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

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Message-ID: <20160210153419.GD14937@odux.rfo.atmel.com>
Date:	Wed, 10 Feb 2016 16:34:19 +0100
From:	Ludovic Desroches <ludovic.desroches@...el.com>
To:	Adrian Hunter <adrian.hunter@...el.com>
CC:	<nicolas.ferre@...el.com>, <ulf.hansson@...aro.org>,
	<linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] mmc: sdhci-of-at91: don't put device in suspend
 after probe

On Wed, Feb 10, 2016 at 04:20:43PM +0200, Adrian Hunter wrote:
> On 10/02/16 16:16, Ludovic Desroches wrote:
> > On Wed, Feb 10, 2016 at 03:00:09PM +0200, Adrian Hunter wrote:
> >> On 10/02/16 14:51, Ludovic Desroches wrote:
> >>> 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.
> >>
> >> Does sdhci-of-at91.c generate card detect interrupts while runtime suspended?
> > 
> > It could if I keep one or two clocks enabled (need extra tests to be
> > sure about the clock needed to get this interrupt). I have tried to modify
> > quickly sdhci_runtime_suspend_host() to enable card insertion/removal,
> > there is an irq generated but the kernel complains this irq is not
> > handled. I didn't dig further, it was only to do a simple test.
> 
> sdhci_irq() returns immediately if (host->runtime_suspended &&
> !sdhci_sdio_irq_enabled(host))

Ok so do I have to rework this part to allow wake up on card detect or
do I have to remove runtime PM from my driver?

> 
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