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| author | Jisheng Zhang <Jisheng.Zhang@synaptics.com> | 2020-10-15 11:41:15 +0200 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2020-10-15 12:29:59 +0200 |
| commit | b3e1ea16fb39fb6e1a1cf1dbdd6738531de3dc7d (patch) | |
| tree | 86fad4c663e0876c0f1adbbe46d464c81cff98e7 /drivers/mmc | |
| parent | Merge tag 'spdx-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gr... (diff) | |
| download | linux-b3e1ea16fb39fb6e1a1cf1dbdd6738531de3dc7d.tar.xz linux-b3e1ea16fb39fb6e1a1cf1dbdd6738531de3dc7d.zip | |
mmc: sdhci: Use Auto CMD Auto Select only when v4_mode is true
sdhci-of-dwcmshc meets an eMMC read performance regression with below
command after commit 427b6514d095 ("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: 427b6514d095 ("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>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/host/sdhci.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 592a55a34b58..3561ae8a481a 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1384,9 +1384,11 @@ static inline void sdhci_auto_cmd_select(struct sdhci_host *host, /* * In case of Version 4.10 or later, use of 'Auto CMD Auto * Select' is recommended rather than use of 'Auto CMD12 - * Enable' or 'Auto CMD23 Enable'. + * Enable' or 'Auto CMD23 Enable'. We require Version 4 Mode + * here because some controllers (e.g sdhci-of-dwmshc) expect it. */ - if (host->version >= SDHCI_SPEC_410 && (use_cmd12 || use_cmd23)) { + if (host->version >= SDHCI_SPEC_410 && host->v4_mode && + (use_cmd12 || use_cmd23)) { *mode |= SDHCI_TRNS_AUTO_SEL; ctrl2 = sdhci_readw(host, SDHCI_HOST_CONTROL2); |