Jisheng Zhang 54ba7d5296 mmc: sdhci: Use Auto CMD Auto Select only when v4_mode is true ...

commit b3e1ea16fb upstream.

sdhci-of-dwcmshc meets an eMMC read performance regression with below
command after commit 427b6514d0 ("mmc: sdhci: Add Auto CMD Auto
Select support"):

dd if=/dev/mmcblk0 of=/dev/null bs=8192 count=100000

Before the commit, the above command gives 120MB/s
After the commit, the above command gives 51.3 MB/s

So it looks like sdhci-of-dwcmshc expects Version 4 Mode for Auto
CMD Auto Select. Fix the performance degradation by ensuring v4_mode
is true to use Auto CMD Auto Select.

Fixes: 427b6514d0 ("mmc: sdhci: Add Auto CMD Auto Select support")
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201015174115.4cf2c19a@xhacker.debian
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2020-11-05 11:51:53 +01:00

..

core

mmc: sdio: Check for CISTPL_VERS_1 buffer size

2020-10-29 10:12:11 +01:00

host

mmc: sdhci: Use Auto CMD Auto Select only when v4_mode is true

2020-11-05 11:51:53 +01:00

Kconfig

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21 10:50:46 +02:00

Makefile

treewide: Add SPDX license identifier - Makefile/Kconfig

2019-05-21 10:50:46 +02:00