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mmc: dw_mmc: don't queue up a card detect at slot startup

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The MMC subsystem handles looking for a card at probe time. Queuing up our
own can race with the rest of the MMC subsystem and cause problems if we
get unlucky with timing. Just remove driver own detection triggering.  While
progressing the request from 'mmc_rescan', if 'dw_mci_work_routine_card'
routine is activated, it will cancel the current request. The problem case
is that 'mmc_rescan' is prior to 'dw_mci_work_routine_card' from host own.
Specifically, the following message shows the detection problem in driver's
probing. It would get an err -123 (-ENOMEDIUM) during probe.

[    4.216595] dwmmc_exynos 12210000.dwmmc1: Using internal DMA controller.
[    4.395935] dwmmc_exynos 12210000.dwmmc1: Version ID is 250a
[    4.401948] dwmmc_exynos 12210000.dwmmc1: DW MMC controller at irq 108, 64 bit host data width, 64 deep fifo
[    4.424430] dwmmc_exynos 12210000.dwmmc1: sdr0 mode (irq=108, width=0)
[    4.453975] dwmmc_exynos 12210000.dwmmc1: sdr0 mode (irq=108, width=0)
[    4.459592] mmc_host mmc1: Bus speed (slot 0) = 100000000Hz (slot req 400000Hz, actual 400000HZ div = 125)
[    4.484258] dwmmc_exynos 12210000.dwmmc1: 1 slots initialized
[    4.485406] dwmmc_exynos 12210000.dwmmc1: sdr0 mode (irq=108, width=0)
[    4.487606] dwmmc_exynos 12210000.dwmmc1: sdr0 mode (irq=108, width=0)
[    4.489794] dwmmc_exynos 12210000.dwmmc1: sdr0 mode (irq=108, width=0)
[    4.509757] mmc1: error -123 whilst initialising SDIO card

Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
This commit is contained in:
Doug Anderson 2013-08-31 00:11:06 +09:00 committed by Chris Ball
parent 357002b9c0
commit 369ac8614f
1 changed files with 0 additions and 6 deletions
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6
drivers/mmc/host/dw_mmc.c
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@ -2008,12 +2008,6 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)
/* Card initially undetected */
slot->last_detect_state = 0;
/*
* Card may have been plugged in prior to boot so we
* need to run the detect tasklet
*/
queue_work(host->card_workqueue, &host->card_work);
return 0;
err_setup_bus: