diff options
authorAnssi Hannula <anssi.hannula@bitwise.fi>2017-02-13 13:46:41 +0200
committerSasha Levin <alexander.levin@verizon.com>2017-03-06 17:31:14 -0500
commit1c12c2f761072fb1e8a2dd938339feb2dd33be80 (patch)
parentf5a7ecc0663f870a44895f08e627adc49c0b5cdf (diff)
mmc: core: fix multi-bit bus width without high-speed mode
[ Upstream commit 3d4ef329757cfd5e0b23cce97cdeca7e2df89c99 ] 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> Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 3ccc89d4c473..1cc1e51a1866 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1415,10 +1415,10 @@ 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;