diff options
| author | Jisheng Zhang <[email protected]> | 2020-10-15 17:41:15 +0800 |
|---|---|---|
| committer | Ulf Hansson <[email protected]> | 2020-10-15 12:29:59 +0200 |
| commit | b3e1ea16fb39fb6e1a1cf1dbdd6738531de3dc7d (patch) | |
| tree | 86fad4c663e0876c0f1adbbe46d464c81cff98e7 | |
| parent | 3e4fb4346c781068610d03c12b16c0cfb0fd24a3 (diff) | |
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 <[email protected]>
Acked-by: Adrian Hunter <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>
| -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); |