linux-kernel - Re: [PATCH] mmc: rtsx: add card power off during probe

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Date:	Thu, 18 Sep 2014 23:14:20 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Roger Tseng <rogerable@...ltek.com>
Cc:	micky <micky_ching@...lsil.com.cn>, Chris Ball <chris@...ntf.net>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	"driverdev-devel@...uxdriverproject.org" 
	<devel@...uxdriverproject.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	Wei_wang <wei_wang@...lsil.com.cn>
Subject: Re: [PATCH] mmc: rtsx: add card power off during probe

[...]

>>
>> In that case, don't forget to enable MMC_CAP2_FULL_PWR_CYCLE.
>>
>> >
>> > if MMC_CAP2_NO_PRESCAN_POWERUP enable, will call mmc_power_off() at start,
>> > then it will check ios.power_mode, but the state is MMC_POWER_OFF and just
>> > return.
>>
>> Uhh, that's right! So, I wonder why we invokes mmc_power_off() from
>> that path at all.
>>
>> Hmm, I think we should change the behavior in mmc_start_host(), like below:
>> 1) Add a "MMC_POWER_UNDEFINED" state which is what the power state
>> should be assigned to at allocation.
>> 2 ) From mmc_start_host(), invoke mmc_power_off() when
>> MMC_CAP2_NO_PRESCAN_POWERUP and MMC_CAP2_FULL_PWR_CYCLE is set.
>>
>> Would that work?
> Yes. I have confirmed this by following changes. The MMC_POWER_UNDEFINED
> designation in mmc_start_host() will eventually cause a power-off
> operation.
>
> But I wonder if we need to additionally check MMC_CAP2_FULL_PWR_CYCLE
> before calling mmc_power_off()?

The intent from my side was to keep the current behaviour for those
that already used MMC_CAP2_NO_PRESCAN_POWERUP, but it's s not a big
deal.

So, let's try your proposal, thus don't check MMC_CAP2_FULL_PWR_CYCLE.

Can you repost new version of your patches and please split them up on
core and host separately.

Kind regards
Uffe
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