Patch "mmc: mmc: Fix incorrect use of driver strength switching HS200 and HS400" has been added to the 4.4-stable tree

Patch "mmc: mmc: Fix incorrect use of driver strength switching HS200 and HS400" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    mmc: mmc: Fix incorrect use of driver strength switching HS200 and HS400

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mmc-mmc-fix-incorrect-use-of-driver-strength-switching-hs200-and-hs400.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From adb24d42a516bca8b9741ed21206509daaab5b13 Mon Sep 17 00:00:00 2001
From: Wenkai Du <wenkai.du@intel.com>
Date: Thu, 26 Nov 2015 14:00:44 +0200
Subject: mmc: mmc: Fix incorrect use of driver strength switching HS200 and HS400

From: Wenkai Du <wenkai.du@intel.com>

commit adb24d42a516bca8b9741ed21206509daaab5b13 upstream.

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 <wenkai.du@intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/mmc/core/mmc.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1076,8 +1076,7 @@ static int mmc_select_hs400(struct mmc_c
 	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 *
 	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);


Patches currently in stable-queue which might be from wenkai.du@intel.com are

queue-4.4/mmc-mmc-fix-incorrect-use-of-driver-strength-switching-hs200-and-hs400.patch