Commit 5a86b115 authored by Anssi Hannula's avatar Anssi Hannula Committed by Greg Kroah-Hartman

mmc: core: fix multi-bit bus width without high-speed mode

commit 3d4ef329 upstream.

Commit 577fb131 ("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: 577fb131 ("mmc: rework selection of bus speed mode")
Signed-off-by: default avatarAnssi Hannula <anssi.hannula@bitwise.fi>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
[anssi.hannula@bitwise.fi: backported for the different err variable
 check on v4.4 and tested]
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6f26f0ba
...@@ -1581,10 +1581,10 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, ...@@ -1581,10 +1581,10 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
err = mmc_select_hs400(card); err = mmc_select_hs400(card);
if (err) if (err)
goto free_card; goto free_card;
} else if (mmc_card_hs(card)) { } else {
/* Select the desired bus width optionally */ /* Select the desired bus width optionally */
err = mmc_select_bus_width(card); 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); err = mmc_select_hs_ddr(card);
if (err) if (err)
goto free_card; goto free_card;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment