From: Anssi Hannula Date: Mon, 13 Feb 2017 11:46:41 +0000 (+0200) Subject: mmc: core: fix multi-bit bus width without high-speed mode X-Git-Tag: v4.10~15^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=3d4ef329757cfd5e0b23cce97cdeca7e2df89c99;p=linux.git 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 Cc: Signed-off-by: Ulf Hansson --- 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;