linux-kernel - RE: [PATCH] mmc: core: disable the cache before suspend only after stopping BKOPS

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Message-ID: <002701cdf1d7$99dd1d00$cd975700$@codeaurora.org>
Date:	Sun, 13 Jan 2013 23:47:21 +0200
From:	"Maya Erez" <merez@...eaurora.org>
To:	"'Subhash Jadavani'" <subhashj@...eaurora.org>
Cc:	<linux-mmc@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
	"'open list'" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] mmc: core: disable the cache before suspend only after stopping BKOPS

-----Original Message-----
From: Subhash Jadavani [mailto:subhashj@...eaurora.org] 
Sent: Saturday, January 12, 2013 9:07 AM
To: Maya Erez
Cc: linux-mmc@...r.kernel.org; linux-arm-msm@...r.kernel.org; open list
Subject: Re: [PATCH] mmc: core: disable the cache before suspend only after
stopping BKOPS

On 1/12/2013 2:12 AM, Maya Erez wrote:
> mmc_cache_ctrl was called in runtime suspend before MMC interrupted 
> BKOPS in case it is still running on the card. This caused the cache 
> disable to timeout.
I guess even if the idle time bkops polling is not implemented, this patch
is good to have. cache control is the eMMC feature and in that sense, it
should have been part of MMC's bus resume (mmc_resume) rather than generic
mmc_suspend_host().

Patch as such is fine and if you agree, you may want to remove the
mentioning of bkops as part of commit text and may just want to mention
above reason as the main motivation for this patch.

Agreed, I will change the commit text in the next uploaded version.

> Therefore, mmc_cache_ctrl has to move to mmc_suspend where we are sure 
> that the card can go into suspend and there is no pending activity.
>
> Signed-off-by: Maya Erez <merez@...eaurora.org>
> ---
>   drivers/mmc/core/core.c |    7 +------
>   drivers/mmc/core/mmc.c  |    8 +++++++-
>   2 files changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 
> aaed768..b438bb2 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2388,6 +2388,7 @@ EXPORT_SYMBOL(mmc_flush_cache);
>    * Turn the cache ON/OFF.
>    * Turning the cache OFF shall trigger flushing of the data
>    * to the non-volatile storage.
> + * This function should be called with host claimed
>    */
>   int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
>   {
> @@ -2399,7 +2400,6 @@ int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
>   			mmc_card_is_removable(host))
>   		return err;
>   
> -	mmc_claim_host(host);
>   	if (card && mmc_card_mmc(card) &&
>   			(card->ext_csd.cache_size > 0)) {
>   		enable = !!enable;
> @@ -2417,7 +2417,6 @@ int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
>   				card->ext_csd.cache_ctrl = enable;
>   		}
>   	}
> -	mmc_release_host(host);
>   
>   	return err;
>   }
> @@ -2436,10 +2435,6 @@ int mmc_suspend_host(struct mmc_host *host)
>   	cancel_delayed_work(&host->detect);
>   	mmc_flush_scheduled_work();
>   
> -	err = mmc_cache_ctrl(host, 0);
> -	if (err)
> -		goto out;
> -
>   	mmc_bus_get(host);
>   	if (host->bus_ops && !host->bus_dead) {
>   		if (host->bus_ops->suspend) {
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 
> e6e3911..dc17d40 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1379,6 +1379,11 @@ static int mmc_suspend(struct mmc_host *host)
>   	BUG_ON(!host->card);
>   
>   	mmc_claim_host(host);
> +
> +	err = mmc_cache_ctrl(host, 0);
> +	if (err)
> +		goto out;
> +
>   	if (mmc_can_poweroff_notify(host->card))
>   		err = mmc_poweroff_notify(host->card,
EXT_CSD_POWER_OFF_SHORT);
>   	else if (mmc_card_can_sleep(host))
> @@ -1386,8 +1391,9 @@ static int mmc_suspend(struct mmc_host *host)
>   	else if (!mmc_host_is_spi(host))
>   		err = mmc_deselect_cards(host);
>   	host->card->state &= ~(MMC_STATE_HIGHSPEED |
MMC_STATE_HIGHSPEED_200);
> -	mmc_release_host(host);
>   
> +out:
> +	mmc_release_host(host);
>   	return err;
>   }
>   
--
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation

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