Re: [PATCH v4] scsi: ufs-mediatek: fix ufs power down specs violation

[Stanley Chu <stanley.chu@mediatek.com>]

Hi Peter,

On Wed, 2021-05-12 at 18:01 +0800, peter.wang@mediatek.com wrote:
> From: Peter Wang <peter.wang@mediatek.com>
> 
> As per specs, e.g, JESD220E chapter 7.2, while powering off
> the ufs device, RST_N signal should be between VSS(Ground)
> and VCCQ/VCCQ2. The power down sequence after fixing as below:
> 
> Power down:
> 1. Assert RST_N low
> 2. Turn-off VCC
> 3. Turn-off VCCQ/VCCQ2
> 
> Signed-off-by: Peter Wang <peter.wang@mediatek.com>
> ---
>  drivers/scsi/ufs/ufs-mediatek.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
> index c55202b..47b4066 100644
> --- a/drivers/scsi/ufs/ufs-mediatek.c
> +++ b/drivers/scsi/ufs/ufs-mediatek.c
> @@ -922,6 +922,7 @@ static void ufs_mtk_vreg_set_lpm(struct ufs_hba *hba, bool lpm)
>  static int ufs_mtk_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>  {
>  	int err;
> +	struct arm_smccc_res res;
>  
>  	if (ufshcd_is_link_hibern8(hba)) {
>  		err = ufs_mtk_link_set_lpm(hba);
> @@ -941,6 +942,9 @@ static int ufs_mtk_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>  			goto fail;
>  	}
>  
> +	if (ufshcd_is_link_off(hba))
> +		ufs_mtk_device_reset_ctrl(0, res);
> +

For the case "linkoff @ suspend", HW reset pin can be de-asserted via
ufshcd_resume() -> ufshcd_reset_and_restore() ->
ufshcd_vops_device_reset(), so this looks good to me.

Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>