From e173f8911f091fa50ccf8cc1fa316dd5569bc470 Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Wed, 9 Nov 2016 21:00:26 +0100 Subject: [PATCH] mmc: core: Update CMD13 polling policy when switch to HS DDR mode According to the JEDEC specification, during bus timing change operations for mmc, sending a CMD13 could trigger CRC errors. As switching to HS DDR mode indeed causes a bus timing change, polling with CMD13 to detect card busy, may thus potentially trigger CRC errors. Currently these errors are treated as the switch to HS DDR mode failed. To improve this behaviour, let's instead tell __mmc_switch() to retry when it encounters CRC errors during polling. Moreover, when switching to HS DDR mode, let's make sure the CMD13 polling is done by having the mmc host and the mmc card, being configured to operate at the same selected bus speed timing. Fix this by providing MMC_TIMING_MMC_DDR52 as the timing parameter to __mmc_switch(). Signed-off-by: Ulf Hansson Tested-by: Linus Walleij Acked-by: Adrian Hunter --- drivers/mmc/core/mmc.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 15dd51cfd083..3268fcd3378d 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1040,10 +1040,12 @@ static int mmc_select_hs_ddr(struct mmc_card *card) ext_csd_bits = (bus_width == MMC_BUS_WIDTH_8) ? EXT_CSD_DDR_BUS_WIDTH_8 : EXT_CSD_DDR_BUS_WIDTH_4; - err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, - EXT_CSD_BUS_WIDTH, - ext_csd_bits, - card->ext_csd.generic_cmd6_time); + err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, + EXT_CSD_BUS_WIDTH, + ext_csd_bits, + card->ext_csd.generic_cmd6_time, + MMC_TIMING_MMC_DDR52, + true, true, true); if (err) { pr_err("%s: switch to bus width %d ddr failed\n", mmc_hostname(host), 1 << bus_width); @@ -1086,9 +1088,6 @@ static int mmc_select_hs_ddr(struct mmc_card *card) if (err) err = __mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330); - if (!err) - mmc_set_timing(host, MMC_TIMING_MMC_DDR52); - return err; } -- 2.20.1