RE: [PATCH 1/2] mmc: core: when downgrading HS400, callback into drivers earlier

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Wolfram-san,

Thank you for the patch!

> From: Wolfram Sang, Sent: Thursday, June 4, 2020 8:21 PM
> 
> The driver specific downgrade function makes more sense if we run it
> before we switch anything, not after we already switched. Otherwise some
> non-HS400 communication has already happened.
> 
> No need to convert users. There is only one currenty which needs this
> change in a later patchset.

Perhaps, should we add Fixes tag like below?

Fixes: ba6c7ac3a2f4 ("mmc: core: more fine-grained hooks for HS400 tuning")

> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/mmc/core/mmc.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 4203303f946a..f97994eace3b 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1156,6 +1156,10 @@ static int mmc_select_hs400(struct mmc_card *card)
>  	      host->ios.bus_width == MMC_BUS_WIDTH_8))
>  		return 0;
> 
> +	/* Prepare host to downgrade to HS timing */
> +	if (host->ops->hs400_downgrade)
> +		host->ops->hs400_downgrade(host);
> +

IICU, we should call hs400_downgrade() between the __mmc_switch("EXT_CSD_TIMING_HS")
and mmc_set_timing(card->host, MMC_TIMING_MMC_HS) because the switch command should
be issued in HS400 mode.

>  	/* Switch card to HS mode */
>  	val = EXT_CSD_TIMING_HS;
>  	err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> @@ -1171,10 +1175,6 @@ static int mmc_select_hs400(struct mmc_card *card)
>  	/* Set host controller to HS timing */
>  	mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
> 
> -	/* Prepare host to downgrade to HS timing */
> -	if (host->ops->hs400_downgrade)
> -		host->ops->hs400_downgrade(host);
> -
>  	/* Reduce frequency to HS frequency */
>  	max_dtr = card->ext_csd.hs_max_dtr;
>  	mmc_set_clock(host, max_dtr);
> @@ -1241,6 +1241,9 @@ int mmc_hs400_to_hs200(struct mmc_card *card)
>  	int err;
>  	u8 val;
> 
> +	if (host->ops->hs400_downgrade)
> +		host->ops->hs400_downgrade(host);
> +

IIUC, this also should be called between
__mmc_switch("EXT_CSD_TIMING_HS") to mmc_set_timing(MMC_TIMING_MMC_DDR52).

Best regards,
Yoshihiro Shimoda





[Index of Archives]     [Linux Samsung SOC]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Device Mapper]

  Powered by Linux