Re: [PATCH v2] mmc: core: Use maximum timeout values in case TACC field is zero

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On 3 April 2014 17:32, Stefan Wahren <stefan.wahren@xxxxxxxx> wrote:
> When plugging a specific micro SD card at MMC socket of a custom i.MX28 board,
> we get the following kernel warning:
>
> WARNING: CPU: 0 PID: 30 at drivers/mmc/host/mxs-mmc.c:342 mxs_mmc_start_cmd+0x34c/0x378()
> Modules linked in:
> CPU: 0 PID: 30 Comm: kworker/u2:1 Not tainted 3.14.0-rc5 #8
> Workqueue: kmmcd mmc_rescan
> [<c0015420>] (unwind_backtrace) from [<c0012cb0>] (show_stack+0x10/0x14)
> [<c0012cb0>] (show_stack) from [<c001daf8>] (warn_slowpath_common+0x6c/0x8c)
> [<c001daf8>] (warn_slowpath_common) from [<c001db34>] (warn_slowpath_null+0x1c/0x24)
> [<c001db34>] (warn_slowpath_null) from [<c0349478>] (mxs_mmc_start_cmd+0x34c/0x378)
> [<c0349478>] (mxs_mmc_start_cmd) from [<c0338fa0>] (mmc_start_request+0xc4/0xf4)
> [<c0338fa0>] (mmc_start_request) from [<c03390b4>] (mmc_wait_for_req+0x50/0x164)
> [<c03390b4>] (mmc_wait_for_req) from [<c03405b8>] (mmc_app_send_scr+0x158/0x1c8)
> [<c03405b8>] (mmc_app_send_scr) from [<c033ee1c>] (mmc_sd_setup_card+0x80/0x3c8)
> [<c033ee1c>] (mmc_sd_setup_card) from [<c033f788>] (mmc_sd_init_card+0x124/0x66c)
> [<c033f788>] (mmc_sd_init_card) from [<c033fd7c>] (mmc_attach_sd+0xac/0x174)
> [<c033fd7c>] (mmc_attach_sd) from [<c033a658>] (mmc_rescan+0x25c/0x2d8)
> [<c033a658>] (mmc_rescan) from [<c003597c>] (process_one_work+0x1b4/0x4ec)
> [<c003597c>] (process_one_work) from [<c0035de4>] (worker_thread+0x130/0x464)
> [<c0035de4>] (worker_thread) from [<c003c824>] (kthread+0xb4/0xd0)
> [<c003c824>] (kthread) from [<c000f420>] (ret_from_fork+0x14/0x34)
>
> The error is due to an invalid value in CSD register of a specific 2GB micro
> SD card. The CSD version of this card is 1.0 but the TACC field has the invalid
> value 0.
>
> cid:0000005553442020000000000000583f
> csd:00000032535a83bfedb7ffbf1680003f
> date:08/2005
> erase_size:512
> fwrev:0x0
> hwrev:0x0
> manfid:0x000000
> name:USD
> oemid:0x0000
> preferred_erase_size:4194304
> scr:0225000000000000
> serial:0x00000000
> type:SD
>
> Since the kernel is making use of this TACC field to calculate the
> SD card timeout, an invalid value 0 leads to a warning at mxs_ns_to_ssp_ticks()
> and later the following misleading error messages appears in a loop:
>
> mxs-mmc 80010000.ssp: card claims to support voltages below defined range
> mxs-mmc 80010000.ssp: no support for card's volts
> mmc0: error -22 whilst initialising MMC card
>
> This error is only found on this 2GB SD card on mxs platform.
> On x86 this card works without any problems.
>
> The following patch based on the work of Peter Chan and Otavio Salvador. It
> catches the case that the determined timeout is still 0 and set
> it's to a valid value.
>
> Successful tested on a i.MX28 board.
>
> Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>

So, maybe we should simplify the commit message a bit? I leave that to
Chris to handle, if he think is needed as well.

Acked-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>


> ---
>
> Changes in v2:
> - fix spelling error in name
> - use local variable with usec for checking
>
>  drivers/mmc/core/core.c |    4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 098374b..74306ec 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -815,6 +815,10 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card)
>                         data->timeout_ns = limit_us * 1000;
>                         data->timeout_clks = 0;
>                 }
> +
> +               /* assign limit value if invalid */
> +               if (timeout_us == 0)
> +                       data->timeout_ns = limit_us * 1000;
>         }
>
>         /*
> --
> 1.7.10.4
>
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