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| author | Anssi Hannula <anssi.hannula@bitwise.fi> | 2017-02-13 13:46:41 +0200 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2017-02-14 08:50:10 +0100 |
| commit | 3d4ef329757cfd5e0b23cce97cdeca7e2df89c99 (patch) | |
| tree | 74bf597f6e43a0d85684dd1db535a29d23d4d29d /drivers/mmc | |
| parent | 7089db84e356562f8ba737c29e472cc42d530dbc (diff) | |
| download | lwn-3d4ef329757cfd5e0b23cce97cdeca7e2df89c99.tar.gz lwn-3d4ef329757cfd5e0b23cce97cdeca7e2df89c99.zip | |
mmc: core: fix multi-bit bus width without high-speed mode
Commit 577fb13199b1 ("mmc: rework selection of bus speed mode")
refactored bus width selection code to mmc_select_bus_width().
However, it also altered the behavior to not call the selection code in
non-high-speed modes anymore.
This causes 1-bit mode to always be used when the high-speed mode is not
enabled, even though 4-bit and 8-bit bus are valid bus widths in the
backwards-compatibility (legacy) mode as well (see e.g. 5.3.2 Bus Speed
Modes in JEDEC 84-B50). This results in a significant regression in
transfer speeds.
Fix the code to allow 4-bit and 8-bit widths even without high-speed
mode, as before.
Tested with a Zynq-7000 PicoZed 7020 board.
Fixes: 577fb13199b1 ("mmc: rework selection of bus speed mode")
Signed-off-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Cc: <stable@vger.kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
| -rw-r--r-- | drivers/mmc/core/mmc.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index b61b52f9da3d..0fccca075e29 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1706,10 +1706,10 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, err = mmc_select_hs400(card); if (err) goto free_card; - } else if (mmc_card_hs(card)) { + } else { /* Select the desired bus width optionally */ err = mmc_select_bus_width(card); - if (err > 0) { + if (err > 0 && mmc_card_hs(card)) { err = mmc_select_hs_ddr(card); if (err) goto free_card; |