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

Paul Fertser
2021-02-22T20:13:51Z

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.

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