[PATCH 3/3] mmc: core: support hs speed mode if hs200 mode fails

[Marcel Ziswiler]

On Thu, 2016-04-21 at 00:51 +0800, Dong Aisheng wrote:
> Currently if mmc_select_hs200 mode switch fails, MMC core
> can only use legacy mode to run the card.
> Let's retry HS speed mode if HS200 fails.
> 
> Before the fix:
> mmc0: mmc_select_hs200 failed, error -74
> : switch to mmc0 failed
> mmc0: new MMC card at address 0001
> mmcblk0: mmc0:0001 Q2J55L 7.12 GiB
> mmcblk0boot0: mmc0:0001 Q2J55L partition 1 2.00 MiB
> mmcblk0boot1: mmc0:0001 Q2J55L partition 2 2.00 MiB
> mmcblk0rpmb: mmc0:0001 Q2J55L partition 3 4.00 MiB
>  mmcblk0: p1 p2
> 
> After the fix:
> mmc0: mmc_select_hs200 failed, error -74
> mmc0: new DDR MMC card at address 0001
> mmcblk0: mmc0:0001 Q2J55L 7.12 GiB
> mmcblk0boot0: mmc0:0001 Q2J55L partition 1 2.00 MiB
> mmcblk0boot1: mmc0:0001 Q2J55L partition 2 2.00 MiB
> mmcblk0rpmb: mmc0:0001 Q2J55L partition 3 4.00 MiB
>  mmcblk0: p1 p2
> 
> Signed-off-by: Dong Aisheng <aisheng.dong at nxp.com>
> ---
>  drivers/mmc/core/mmc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 55c8201..b573dc7 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1315,7 +1315,8 @@ static int mmc_select_timing(struct mmc_card
> *card)
>  
>  	if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS200)
>  		err = mmc_select_hs200(card);
> -	else if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS)
> +
> +	if (err && (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS))
>  		err = mmc_select_hs(card);
>  
>  	if (err && err != -EBADMSG)


This seems to break on TK1 where eMMC so far was detected as an 8-bit
high speed MMC card. With this patch it reverts to detecting a 1-bit only
MMC card! This has been observed both on a NVIDIA's Jetson TK1 as well as
our new Toradex Apalis TK1 (CC Tegra mailing list, Jon Hunter and Lucas
Stach as well). So far T30 is not affected as there we are still doing
full HS200 with whatever issues that has.

Before:
[    3.726894] sdhci: Secure Digital Host Controller Interface driver
[    3.733081] sdhci: Copyright(c) Pierre Ossman
[    3.737462] sdhci-pltfm: SDHCI platform and OF driver helper
[    3.753411] mmc0: Unknown controller version (3). You may experience
 problems.
[    3.768345] mmc0: Invalid maximum block size, assuming 512 bytes
[    3.814896] mmc0: SDHCI controller on 700b0600.sdhci [700b0600.sdhci]
 using ADMA 64-bit
[    3.892088] mmc0: new high speed MMC card at address 0001
[    3.899194] mmcblk0: mmc0:0001 SEM16G 14.7 GiB
[    3.904217] mmcblk0boot0: mmc0:0001 SEM16G partition 1 4.00 MiB
[    3.910645] mmcblk0boot1: mmc0:0001 SEM16G partition 2 4.00 MiB
[    3.917119] mmcblk0rpmb: mmc0:0001 SEM16G partition 3 4.00 MiB
[    3.926006]  mmcblk0: p1 p2 p3 p4 p5 p6 p7 p8 p9
root at jetson_tk1:~# cat /sys/kernel/debug/mmc0/ios 
clock:          52000000 Hz
actual clock:   51000000 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    1 (mmc high-speed)
signal voltage: 0 (3.30 V)
driver type:    0 (driver type B)

After:
[    3.899918] mmc0: new MMC card at address 0001
root at jetson_tk1:~# cat /sys/kernel/debug/mmc0/ios 
clock:          25000000 Hz
actual clock:   24727273 Hz
vdd:            21 (3.3 ~ 3.4 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      0 (1 bits)
timing spec:    0 (legacy)
signal voltage: 0 (3.30 V)
driver type:    0 (driver type B)