linux-kernel - RE: [EXT] [PATCH v1 1/4] scsi: ufs: allow legacy UFS devices to enable WriteBooster

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Date:   Wed, 29 Apr 2020 10:18:22 +0000
From:   "Bean Huo (beanhuo)" <beanhuo@...ron.com>
To:     Stanley Chu <stanley.chu@...iatek.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "avri.altman@....com" <avri.altman@....com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>
CC:     "cang@...eaurora.org" <cang@...eaurora.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kuohong.wang@...iatek.com" <kuohong.wang@...iatek.com>,
        "peter.wang@...iatek.com" <peter.wang@...iatek.com>,
        "chun-hung.wu@...iatek.com" <chun-hung.wu@...iatek.com>,
        "andy.teng@...iatek.com" <andy.teng@...iatek.com>
Subject: RE: [EXT] [PATCH v1 1/4] scsi: ufs: allow legacy UFS devices to
 enable WriteBooster

> -----Original Message-----
> From: Stanley Chu <stanley.chu@...iatek.com>
> Sent: Tuesday, April 28, 2020 1:14 PM
> To: linux-scsi@...r.kernel.org; martin.petersen@...cle.com;
> avri.altman@....com; alim.akhtar@...sung.com; jejb@...ux.ibm.com;
> asutoshd@...eaurora.org
> Cc: Bean Huo (beanhuo) <beanhuo@...ron.com>; cang@...eaurora.org;
> matthias.bgg@...il.com; bvanassche@....org; linux-
> mediatek@...ts.infradead.org; linux-arm-kernel@...ts.infradead.org; linux-
> kernel@...r.kernel.org; kuohong.wang@...iatek.com;
> peter.wang@...iatek.com; chun-hung.wu@...iatek.com;
> andy.teng@...iatek.com; Stanley Chu <stanley.chu@...iatek.com>
> Subject: [EXT] [PATCH v1 1/4] scsi: ufs: allow legacy UFS devices to enable
> WriteBooster
> 
> WriteBooster feature may be supported by some legacy UFS devices (i.e., < 3.1)
> by upgrading firmware.
> 
> To enable WriteBooster feature in such devices, relax the entrance condition of
> ufshcd_wb_probe() to allow host driver to check those devices' WriteBooster
> capability.
> 
> WriteBooster feature can be available if below both conditions are satisfied,
> 
> 1. Device descriptor has dExtendedUFSFeaturesSupport field.
> 2. WriteBooster support is specified in above field.
> 
> Signed-off-by: Stanley Chu <stanley.chu@...iatek.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c index
> 915e963398c4..111812c5304a 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -6800,9 +6800,16 @@ static int ufshcd_scsi_add_wlus(struct ufs_hba *hba)
> 
>  static void ufshcd_wb_probe(struct ufs_hba *hba, u8 *desc_buf)  {
> +	if (hba->desc_size.dev_desc <=
> DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP)
> +		goto wb_disabled;
> +
>  	hba->dev_info.d_ext_ufs_feature_sup =
>  		get_unaligned_be32(desc_buf +
> 
> DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP);
> +
> +	if (!(hba->dev_info.d_ext_ufs_feature_sup &
> UFS_DEV_WRITE_BOOSTER_SUP))
> +		goto wb_disabled;
> +
>  	/*
>  	 * WB may be supported but not configured while provisioning.
>  	 * The spec says, in dedicated wb buffer mode, @@ -6818,11 +6825,12
> @@ static void ufshcd_wb_probe(struct ufs_hba *hba, u8 *desc_buf)
>  	hba->dev_info.b_presrv_uspc_en =
>  		desc_buf[DEVICE_DESC_PARAM_WB_PRESRV_USRSPC_EN];
> 
> -	if (!((hba->dev_info.d_ext_ufs_feature_sup &
> -		 UFS_DEV_WRITE_BOOSTER_SUP) &&
> -		hba->dev_info.b_wb_buffer_type &&
> +	if (!(hba->dev_info.b_wb_buffer_type &&
>  	      hba->dev_info.d_wb_alloc_units))
> -		hba->caps &= ~UFSHCD_CAP_WB_EN;
> +		goto wb_disabled;
> +
> +wb_disabled:
> +	hba->caps &= ~UFSHCD_CAP_WB_EN;
>  }
> 
>  static int ufs_get_device_desc(struct ufs_hba *hba) @@ -6862,8 +6870,7 @@
> static int ufs_get_device_desc(struct ufs_hba *hba)
> 
>  	model_index = desc_buf[DEVICE_DESC_PARAM_PRDCT_NAME];
> 
> -	/* Enable WB only for UFS-3.1 */
> -	if (dev_info->wspecversion >= 0x310)
> +	if (ufshcd_is_wb_allowed(hba))
>  		ufshcd_wb_probe(hba, desc_buf);
> 
>  	err = ufshcd_read_string_desc(hba, model_index,
> --
> 2.18.0

Reviewed-by: Bean Huo <beanhuo@...ron.com>