linux-kernel - Re: [PATCH 2/3] scsi: ufs: Keep device power on only fWriteBoosterBufferFlushDuringHibernate == 1

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Date:   Fri, 04 Dec 2020 11:26:14 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Bean Huo <huobean@...il.com>
Cc:     alim.akhtar@...sung.com, avri.altman@....com,
        asutoshd@...eaurora.org, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, stanley.chu@...iatek.com,
        beanhuo@...ron.com, bvanassche@....org, tomas.winkler@...el.com,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] scsi: ufs: Keep device power on only
 fWriteBoosterBufferFlushDuringHibernate == 1

On 2020-12-01 02:11, Bean Huo wrote:
> From: Bean Huo <beanhuo@...ron.com>
> 
> Keep device power mode as active power mode and VCC supply only if
> fWriteBoosterBufferFlushDuringHibernate setting 1 is successful.
> 
> Signed-off-by: Bean Huo <beanhuo@...ron.com>
> ---
>  drivers/scsi/ufs/ufs.h    |  2 ++
>  drivers/scsi/ufs/ufshcd.c | 11 ++++++++++-
>  2 files changed, 12 insertions(+), 1 deletion(-)
> 
> 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;
>  	/* 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 639ba9d1ccbb..eb7a2534b072 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;
> +	} else {
> +		hba->dev_info.is_hibern8_wb_flush = true;
> +	}
> +
>  	ufshcd_wb_toggle_flush(hba, true);
>  }
> 
> @@ -5440,6 +5446,9 @@ static bool ufshcd_wb_need_flush(struct ufs_hba 
> *hba)
> 
>  	if (!ufshcd_is_wb_allowed(hba))
>  		return false;
> +
> +	if (!hba->dev_info.is_hibern8_wb_flush)
> +		return false;

The check is in the wrong place - even if say
fWriteBoosterBufferFlushDuringHibernate is failed to be enabled,
ufshcd_wb_need_flush() still needs to reflect the fact that whether
the wb buffer needs to be flushed or not - it should not be decided
by the flag.

Thanks,

Can Guo.

>  	/*
>  	 * The ufs device needs the vcc to be ON to flush.
>  	 * With user-space reduction enabled, it's enough to enable flush