linux-kernel - Re: [RFC PATCH 2/2] mmc: core: sdio: claim host before power up or power off

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Message-ID: <55F2D466.30806@ti.com>
Date:	Fri, 11 Sep 2015 18:47:26 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Ulf Hansson <ulf.hansson@...aro.org>
CC:	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Sekhar Nori <nsekhar@...com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Neil Brown <neilb@...e.de>,
	"Fu, Zhonghui" <zhonghui.fu@...ux.intel.com>,
	Andreas Fenkart <afenkart@...il.com>
Subject: Re: [RFC PATCH 2/2] mmc: core: sdio: claim host before power up or
 power off

Hi,

On Friday 11 September 2015 06:15 PM, Ulf Hansson wrote:
> On 24 August 2015 at 12:15, Kishon Vijay Abraham I <kishon@...com> wrote:
>> mmc_sdio_runtime_resume and mmc_sdio_runtime_suspend does power up and
>> power off respectively but does so without claiming the host. Among other
>> things mmc_claim_host inovkes pm_runtime_get_sync to enable the clocks.
>> Invoke mmc_claim_host before mmc_power_up and mmc_power_off in
>> mmc_sdio_runtime_resume and mmc_sdio_runtime_suspend respectively.
>>
>> This is required since certain platforms (like TI SoCs) access
>> the controller registers during power up.
> 
> I realize the issue. Actually I have been working on similar patch
> which take a bit wider approach. That's because there are more cases
> where the host needs to be claimed, when it isn't.
> 
> I just posted a patch, please have a look and see if it makes sense to
> you, you are on cc.
> "[PATCH] mmc: core: Keep host claimed while invoking mmc_power_off|up()"

Sure Uffe.

-Kishon

> 
> Kind regards
> Uffe
> 
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
>> ---
>>  drivers/mmc/core/sdio.c |   10 +++++++++-
>>  1 file changed, 9 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
>> index 0cbbfb8..40795b2 100644
>> --- a/drivers/mmc/core/sdio.c
>> +++ b/drivers/mmc/core/sdio.c
>> @@ -1023,16 +1023,24 @@ static int mmc_sdio_power_restore(struct mmc_host *host)
>>
>>  static int mmc_sdio_runtime_suspend(struct mmc_host *host)
>>  {
>> +       mmc_claim_host(host);
>>         /* No references to the card, cut the power to it. */
>>         mmc_power_off(host);
>> +       mmc_release_host(host);
>>         return 0;
>>  }
>>
>>  static int mmc_sdio_runtime_resume(struct mmc_host *host)
>>  {
>> +       int ret;
>> +
>> +       mmc_claim_host(host);
>>         /* Restore power and re-initialize. */
>>         mmc_power_up(host, host->card->ocr);
>> -       return mmc_sdio_power_restore(host);
>> +       ret = _mmc_sdio_power_restore(host);
>> +       mmc_release_host(host);
>> +
>> +       return ret;
>>  }
>>
>>  static int mmc_sdio_reset(struct mmc_host *host)
>> --
>> 1.7.9.5
>>
--
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