| From b3e1ea16fb39fb6e1a1cf1dbdd6738531de3dc7d Mon Sep 17 00:00:00 2001 |
| From: Jisheng Zhang <Jisheng.Zhang@synaptics.com> |
| Date: Thu, 15 Oct 2020 17:41:15 +0800 |
| Subject: mmc: sdhci: Use Auto CMD Auto Select only when v4_mode is true |
| |
| From: Jisheng Zhang <Jisheng.Zhang@synaptics.com> |
| |
| commit b3e1ea16fb39fb6e1a1cf1dbdd6738531de3dc7d upstream. |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/mmc/host/sdhci.c | 6 ++++-- |
| 1 file changed, 4 insertions(+), 2 deletions(-) |
| |
| --- a/drivers/mmc/host/sdhci.c |
| +++ b/drivers/mmc/host/sdhci.c |
| @@ -1384,9 +1384,11 @@ static inline void sdhci_auto_cmd_select |
| /* |
| * 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); |