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authorAnssi Hannula <anssi.hannula@bitwise.fi>2017-02-13 13:46:41 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-23 17:43:10 +0100
commit5a86b1150f6ce88c43d669bfe14c96b312a1cceb (patch)
parent6f26f0ba2435a49179b5f9c452afde0600e24987 (diff)
mmc: core: fix multi-bit bus width without high-speed mode
commit 3d4ef329757cfd5e0b23cce97cdeca7e2df89c99 upstream. 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> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> [anssi.hannula@bitwise.fi: backported for the different err variable check on v4.4 and tested] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 78187699467a..79a0c26e1419 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1581,10 +1581,10 @@ 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 (!IS_ERR_VALUE(err)) {
+ if (!IS_ERR_VALUE(err) && mmc_card_hs(card)) {
err = mmc_select_hs_ddr(card);
if (err)
goto free_card;