Re: [PATCH v2 2/3] scsi: ufs: Keep device active mode only fWriteBoosterBufferFlushDuringHibernate == 1

[Stanley Chu]

On Sun, 2020-12-06 at 11:13 +0100, Bean Huo wrote:
> From: Bean Huo <beanhuo@xxxxxxxxxx>
> 
> According to the JEDEC UFS 3.1 Spec, If fWriteBoosterBufferFlushDuringHibernate
> is set to one, the device flushes the WriteBooster Buffer data automatically
> whenever the link enters the hibernate (HIBERN8) state. While the flushing
> operation is in progress, the device should be kept in Active power mode.
> Currently, we set this flag during the UFSHCD probe stage, but we didn't deal
> with its programming failure. Even this failure is less likely to occur, but
> still it is possible.
> This patch is to add checkup of fWriteBoosterBufferFlushDuringHibernate setting,
> keep the device as "active power mode" only when this flag be successfully set
> to 1.
> 
> Fixes: 51dd905bd2f6 ("scsi: ufs: Fix WriteBooster flush during runtime suspend")
> Signed-off-by: Bean Huo <beanhuo@xxxxxxxxxx>
> ---
>  drivers/scsi/ufs/ufs.h    |  2 ++
>  drivers/scsi/ufs/ufshcd.c | 20 +++++++++++++++-----
>  2 files changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufs.h b/drivers/scsi/ufs/ufs.h
> index d593edb48767..311d5f7a024d 100644
> --- a/drivers/scsi/ufs/ufs.h
> +++ b/drivers/scsi/ufs/ufs.h
> @@ -530,6 +530,8 @@ struct ufs_dev_info {
>  	bool f_power_on_wp_en;
>  	/* Keeps information if any of the LU is power on write protected */
>  	bool is_lu_power_on_wp;
> +	/* Indicates if flush WB buffer during hibern8 successfully enabled */
> +	bool is_hibern8_wb_flush;

Perhaps a more comprehensive name?
For example, wb_flush_during_hibern8?
>  	/* Maximum number of general LU supported by the UFS device */
>  	u8 max_lu_supported;
>  	u8 wb_dedicated_lu;
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 30332592e624..da38d760944b 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -285,10 +285,16 @@ static inline void ufshcd_wb_config(struct ufs_hba *hba)
>  		dev_err(hba->dev, "%s: Enable WB failed: %d\n", __func__, ret);
>  	else
>  		dev_info(hba->dev, "%s: Write Booster Configured\n", __func__);
> +
>  	ret = ufshcd_wb_toggle_flush_during_h8(hba, true);
> -	if (ret)
> +	if (ret) {
>  		dev_err(hba->dev, "%s: En WB flush during H8: failed: %d\n",
>  			__func__, ret);
> +		hba->dev_info.is_hibern8_wb_flush = false;

Perhaps this statement could be dummy because
hba->dev_info.is_hibern8_wb_flush is zero-initialized and
ufshcd_wb_config() is invoked only once during ufs initialization.

Thanks,
Stanley Chu

> +	} else {
> +		hba->dev_info.is_hibern8_wb_flush = true;
> +	}
> +
>  	ufshcd_wb_toggle_flush(hba, true);
>  }
>  
> @@ -5448,6 +5454,7 @@ static bool ufshcd_wb_need_flush(struct ufs_hba *hba)
>  
>  	if (!ufshcd_is_wb_allowed(hba))
>  		return false;
> +
>  	/*
>  	 * The ufs device needs the vcc to be ON to flush.
>  	 * With user-space reduction enabled, it's enough to enable flush
> @@ -8540,6 +8547,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>  	enum ufs_pm_level pm_lvl;
>  	enum ufs_dev_pwr_mode req_dev_pwr_mode;
>  	enum uic_link_state req_link_state;
> +	bool hibern8;
>  
>  	hba->pm_op_in_progress = 1;
>  	if (!ufshcd_is_shutdown_pm(pm_op)) {
> @@ -8599,11 +8607,13 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
>  		 * Hibern8, keep device power mode as "active power mode"
>  		 * and VCC supply.
>  		 */
> +		hibern8 = req_link_state == UIC_LINK_HIBERN8_STATE ||
> +			(req_link_state == UIC_LINK_ACTIVE_STATE &&
> +			 ufshcd_is_auto_hibern8_enabled(hba));
> +
>  		hba->dev_info.b_rpm_dev_flush_capable =
> -			hba->auto_bkops_enabled ||
> -			(((req_link_state == UIC_LINK_HIBERN8_STATE) ||
> -			((req_link_state == UIC_LINK_ACTIVE_STATE) &&
> -			ufshcd_is_auto_hibern8_enabled(hba))) &&
> +			hba->auto_bkops_enabled || (hibern8 &&
> +			hba->dev_info.is_hibern8_wb_flush &&
>  			ufshcd_wb_need_flush(hba));
>  	}
>