[PATCH 1/3] mmc: fix mmc mode selection for HS-DDR and higher
From: Ulf Hansson <hidden>
Date: 2016-06-02 08:31:17
Also in:
linux-mmc, lkml
+ Linus On 29 May 2016 at 09:04, Chen-Yu Tsai [off-list ref] wrote:
quoted hunk ↗ jump to hunk
When IS_ERR_VALUE was removed from the mmc core code, it was replaced with a simple not-zero check. This does not work, as the value checked is the return value for mmc_select_bus_width, which returns the set bit width on success. This made eMMC modes higher than HS-DDR unusable. Fix this by checking for a positive return value instead. Fixes: 287980e49ffc ("remove lots of IS_ERR_VALUE abuses") Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Chen-Yu Tsai <redacted> --- drivers/mmc/core/mmc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index c984321d1881..aafb73d080ca 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c@@ -1276,7 +1276,7 @@ static int mmc_select_hs200(struct mmc_card *card) * switch to HS200 mode if bus width is set successfully. */ err = mmc_select_bus_width(card); - if (!err) { + if (err > 0) { val = EXT_CSD_TIMING_HS200 | card->drive_strength << EXT_CSD_DRV_STR_SHIFT; err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,@@ -1583,7 +1583,7 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr, } else if (mmc_card_hs(card)) { /* Select the desired bus width optionally */ err = mmc_select_bus_width(card); - if (!err) { + if (err > 0) {
As pointed out in the review by Bj?rn, to restore the old behaviour we should check for "err >= 0". No need to send a new patch, I can amend the current version.
err = mmc_select_hs_ddr(card);
if (err)
goto free_card;
--
2.8.1
Finally, I am a little concerned about the commit 287980e49ffc
("remove lots of IS_ERR_VALUE abuses") which introduced this
regression.
Surprisingly the IS_ERR_VALUE():s aren't being replaced by equivalent
checks, so perhaps there a more regressions. Moreover, I wonder why I
wasn't being on cc/to list when this patch was submitted a few days
ago, perhaps my review could prevented the regression from even
happen.
Anyway, let's fix this now! I will pick up $subject patch as fix asap...
and Arnd, can you please double-check that the commit 287980e49ffc
doesn?t seems to regress anything else!?
Kind regards
Uffe