On 25 October 2018 at 04:59, Yinbo Zhu <yinbo.zhu@xxxxxxx> wrote:
> Some SD controllers need specific settings for HS400 mode
> before the speed mode is been switching from DDR mode to
> HS400 mode. This patch is to add prepare_ddr_to_hs400 callback
> for this.
>
> Signed-off-by: Yinbo Zhu <yinbo.zhu@xxxxxxx>
> ---
> Change in v4:
> post this as part of patch series
>
> drivers/mmc/core/mmc.c | 3 +++
> include/linux/mmc/host.h | 1 +
> 2 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index bc1bd2c..749c5f2 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1182,6 +1182,9 @@ static int mmc_select_hs400(struct mmc_card *card)
> goto out_err;
>
> /* Switch card to DDR */
> + if (host->ops->prepare_ddr_to_hs400)
> + host->ops->prepare_ddr_to_hs400(host);
The code is starting to become a bit messy with all the hs400 related
callbacks, however I guess there is no other option - so I am fine
with adding this.
Although, please rename the callback to "hs400_prepare_ddr" to make
its purpose more clear and aligned with other "hs400" callbacks.
> +
> err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> EXT_CSD_BUS_WIDTH,
> EXT_CSD_DDR_BUS_WIDTH_8,
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 2a5fe75..a44544e 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -146,6 +146,7 @@ struct mmc_host_ops {
>
> /* Prepare HS400 target operating frequency depending host driver */
> int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
> + int (*prepare_ddr_to_hs400)(struct mmc_host *host);
Please add a comment above the new callback, something along the lines of:
"Prepare switch to DDR during the HS400 init sequence."
>
> /* Prepare for switching from HS400 to HS200 */
> void (*hs400_downgrade)(struct mmc_host *host);
> --
> 1.7.1
>
Kind regards
Uffe
