From adb24d42a516bca8b9741ed21206509daaab5b13 Mon Sep 17 00:00:00 2001 From: Wenkai Du Date: Thu, 26 Nov 2015 14:00:44 +0200 Subject: [PATCH] mmc: mmc: Fix incorrect use of driver strength switching HS200 and HS400 Commit cc4f414c885c ("mmc: mmc: Add driver strength selection") added driver strength selection for eMMC HS200 and HS400 modes. That patch also set the driver stength when transitioning through High Speed mode to HS200/HS400, but driver strength is not defined for High Speed mode. While the JEDEC specification is not clear on this point it has been observed to cause problems for some eMMC, and removing the driver strength setting in this case makes it consistent with the normal use of High Speed mode. Signed-off-by: Wenkai Du Signed-off-by: Adrian Hunter Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: Ulf Hansson --- drivers/mmc/core/mmc.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index 66957ad..549c56e 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1076,8 +1076,7 @@ static int mmc_select_hs400(struct mmc_card *card) mmc_set_clock(host, max_dtr); /* Switch card to HS mode */ - val = EXT_CSD_TIMING_HS | - card->drive_strength << EXT_CSD_DRV_STR_SHIFT; + val = EXT_CSD_TIMING_HS; err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING, val, card->ext_csd.generic_cmd6_time, @@ -1160,8 +1159,7 @@ int mmc_hs400_to_hs200(struct mmc_card *card) mmc_set_clock(host, max_dtr); /* Switch HS400 to HS DDR */ - val = EXT_CSD_TIMING_HS | - card->drive_strength << EXT_CSD_DRV_STR_SHIFT; + val = EXT_CSD_TIMING_HS; err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL, EXT_CSD_HS_TIMING, val, card->ext_csd.generic_cmd6_time, true, send_status, true); -- 2.7.4