Re: [PATCH 1/3] mmc: fix mmc mode selection for HS-DDR and higher

[Marcel Ziswiler]

On Sun, 2016-05-29 at 15:04 +0800, Chen-Yu Tsai wrote:
> 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@xxxxxxxx>
> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>

This fixes the following eMMC issue as experienced on Apalis T30 as
well:

[ÂÂÂÂ7.194625] mmc1: mmc_select_hs200 failed, error 3
[ÂÂÂÂ7.201549] mmc1: error 3 whilst initialising MMC card

Tested-by: Marcel Ziswiler <marcel.ziswiler@xxxxxxxxxxx>

> ---
> Âdrivers/mmc/core/mmc.c | 4 ++--
> Â1 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)
> Â	Â* switch to HS200 mode if bus width is set successfully.
> Â	Â*/
> Â	err = mmc_select_bus_width(card);
> -	if (!err) {
> +	if (err > 0) {
> Â		val = EXT_CSD_TIMING_HS200 |
> Â		ÂÂÂÂÂÂcard->drive_strength << EXT_CSD_DRV_STR_SHIFT;
> Â		err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> @@ -1583,7 +1583,7 @@ static int mmc_init_card(struct mmc_host *host,
> u32 ocr,
> Â	} else if (mmc_card_hs(card)) {
> Â		/* Select the desired bus width optionally */
> Â		err = mmc_select_bus_width(card);
> -		if (!err) {
> +		if (err > 0) {
> Â			err = mmc_select_hs_ddr(card);
> Â			if (err)
> Â				goto free_card;