RE: [PATCH] sdio: add MMC_PM_SKIP_RESUME_PROBE to workaround powered resume

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Hi Wilson,

> -----Original Message-----
> From: Wilson Loi [mailto:wlsloi@xxxxxxxxx]
> Sent: Wednesday, September 01, 2010 5:33 PM
> To: Bing Zhao
> Cc: Michał Mirosław; Chris Ball; linux-mmc@xxxxxxxxxxxxxxx; Nicolas Pitre; Andrew Morton
> Subject: Re: [PATCH] sdio: add MMC_PM_SKIP_RESUME_PROBE to workaround powered resume
> 
> It should be necessary for this flags.
> Some WLAN card will put itself either into deep sleep or host wake up mode.
> They don't need to re-init after resume.

The MMC_PM_KEEP_POWER flag can be set in suspend handler before WLAN card is put into any power saving mode. When system resumes re-init attempt will be skipped as MMC_PM_KEEP_POWER is set.

Regards,

Bing

> 
> 
> 2010/9/2 Bing Zhao <bzhao@xxxxxxxxxxx>
> 
> 
> 	Hi Michal,
> 
> 	Thanks for your comment.
> 
> 
> 	> -----Original Message-----
> 	> From: Michał Mirosław [mailto:mirqus@xxxxxxxxx]
> 	> Sent: Wednesday, September 01, 2010 11:40 AM
> 	> To: Chris Ball
> 	> Cc: Bing Zhao; linux-mmc@xxxxxxxxxxxxxxx; Nicolas Pitre; Andrew Morton
> 	> Subject: Re: [PATCH] sdio: add MMC_PM_SKIP_RESUME_PROBE to workaround powered resume
> 	>
> 	> 2010/8/27 Chris Ball <cjb@xxxxxxxxxx>:
> 	> > Any comments on this patch from the list?
> 	> >
> 	> > From: Bing Zhao <bzhao@xxxxxxxxxxx>
> 	> > Date: Wed, 21 Jul 2010 18:46:55 -0700
> 	> >
> 	> > Marvell 8686/8688 device will not respond to re-probe attemps
> 	> > in powered resume, if the card is in sleep mode.
> 	> > The added MMC_PM_SKIP_RESUME_PROBE flag is checked so that
> 	> > call to mmc_sdio_init_card() can be skipped.
> 	> [patch cut]
> 	>
> 	> Simplified SDIO spec v.2.00 (section 6.14 - Bus State Diagram)
> 	> suggests, that initialization commands (CMD5, CMD3) are not accepted
> 	> in CMD state. As the card stays in that state on powered suspend (no
> 	> resetting CMD52 nor power cycle is issued) then reinitialization
> 	> should be entirely skipped on resume unless the power was lost between
> 	> suspend and resume (or card was temporarily removed from the slot).
> 
> 
> 	With that said, skipping initialization on powered resume is needed in general. We can just
> check MMC_PM_KEEP_POWER flag to skip the card initialization.
> 
> 	I will send the updated patch.
> 
> 	Regards,
> 
> 	Bing
> 
> 
> 	>
> 	> Best Regards,
> 	> Michał Mirosław
> 	--
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> 
> 
> 
> 
> --
> Best regards,
> Wilson
> http://blog.roodo.com/wlsloi

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