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. 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 Chen 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> --- 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..a9cd996 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 (data->timeout_ns == 0) + data->timeout_ns = limit_us * 1000; } /* -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
