Re: [PATCH 3/3] mmc: core: Default to generic_cmd6_time as timeout in __mmc_switch()

From: Ulf Hansson <ulf.hansson@linaro.org>
To: Paul Fertser <fercerpav@gmail.com>
Cc: "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
	"Adrian Hunter" <adrian.hunter@intel.com>,
	"Chaotian Jing" <chaotian.jing@mediatek.com>,
	"Shawn Lin" <shawn.lin@rock-chips.com>,
	"Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Subject: Re: [PATCH 3/3] mmc: core: Default to generic_cmd6_time as timeout in __mmc_switch()
Date: Tue, 23 Feb 2021 10:23:28 +0100	[thread overview]
Message-ID: <CAPDyKFpXceh0qWZMxnOnLmrnwyt==qWWaxHCYzb6UxGRcvgksA@mail.gmail.com> (raw)
In-Reply-To: <20210222201245.GW2059@home.paul.comp>

On Mon, 22 Feb 2021 at 21:12, Paul Fertser <fercerpav@gmail.com> wrote:
>
> On Mon, Feb 22, 2021 at 07:24:06PM +0300, Paul Fertser wrote:
> > On Wed, Jan 22, 2020 at 03:27:47PM +0100, Ulf Hansson wrote:
> > > All callers of __mmc_switch() should now be specifying a valid timeout for
> > > the CMD6 command.
> >
> > I'm running a kernel based on linux-next on a Tegra2 system (Toshiba
> > ac100 aka paz00, on-board eMMC) and seeing plenty of these warnings on
> > boot. I added WARN_ON_ONCE to see the backtrace and here's what I get:
> ...
> > [    3.338454] [<c063d8a4>] (mmc_switch) from [<c0648f48>] (mmc_blk_mq_issue_rq+0x22c/0x900)
> > [    3.396728] [<c0648f48>] (mmc_blk_mq_issue_rq) from [<c064998c>] (mmc_mq_queue_rq+0x124/0x258)
> > [    3.409215] [<c064998c>] (mmc_mq_queue_rq) from [<c039a9e8>] (__blk_mq_try_issue_directly+0x140/0x1cc)
>
> FWIW, with
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index f5dedb7f9b27..9adf735391fa 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -426,8 +426,7 @@ static int mmc_decode_ext_csd(struct mmc_card *card, u8 *ext_csd)
>                 /* EXT_CSD value is in units of 10ms, but we store in ms */
>                 card->ext_csd.part_time = 10 * ext_csd[EXT_CSD_PART_SWITCH_TIME];
>                 /* Some eMMC set the value too low so set a minimum */
> -               if (card->ext_csd.part_time &&
> -                   card->ext_csd.part_time < MMC_MIN_PART_SWITCH_TIME)
> +               if (card->ext_csd.part_time < MMC_MIN_PART_SWITCH_TIME)
>                         card->ext_csd.part_time = MMC_MIN_PART_SWITCH_TIME;
>
>                 /* Sleep / awake timeout in 100ns units */
>
> I do not see any more warnings on my system.

That looks like the correct fix to the problem. Do you want to send a
proper patch that I can pick up or do you prefer if help to do it?

Seems like we should add the following fixes tag as well.
Fixes: 1c447116d017 ("mmc: mmc: Fix partition switch timeout for some eMMCs")

Kind regards
Uffe