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To:     Stanley Chu <stanley.chu@mediatek.com>,
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Subject: RE: [EXT] [PATCH v1 1/4] scsi: ufs: allow legacy UFS devices to
 enable WriteBooster
Thread-Topic: [EXT] [PATCH v1 1/4] scsi: ufs: allow legacy UFS devices to
 enable WriteBooster
Thread-Index: AQHWHU4iZoA14hvpQ0SN1N4w8h0dMqiP5DJQ
Date:   Wed, 29 Apr 2020 10:18:22 +0000
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References: <20200428111355.1776-1-stanley.chu@mediatek.com>
 <20200428111355.1776-2-stanley.chu@mediatek.com>
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> -----Original Message-----
> From: Stanley Chu <stanley.chu@mediatek.com>
> Sent: Tuesday, April 28, 2020 1:14 PM
> To: linux-scsi@vger.kernel.org; martin.petersen@oracle.com;
> avri.altman@wdc.com; alim.akhtar@samsung.com; jejb@linux.ibm.com;
> asutoshd@codeaurora.org
> Cc: Bean Huo (beanhuo) <beanhuo@micron.com>; cang@codeaurora.org;
> matthias.bgg@gmail.com; bvanassche@acm.org; linux-
> mediatek@lists.infradead.org; linux-arm-kernel@lists.infradead.org; linux=
-
> kernel@vger.kernel.org; kuohong.wang@mediatek.com;
> peter.wang@mediatek.com; chun-hung.wu@mediatek.com;
> andy.teng@mediatek.com; Stanley Chu <stanley.chu@mediatek.com>
> Subject: [EXT] [PATCH v1 1/4] scsi: ufs: allow legacy UFS devices to enab=
le
> WriteBooster
>=20
> WriteBooster feature may be supported by some legacy UFS devices (i.e., <=
 3.1)
> by upgrading firmware.
>=20
> To enable WriteBooster feature in such devices, relax the entrance condit=
ion of
> ufshcd_wb_probe() to allow host driver to check those devices' WriteBoost=
er
> capability.
>=20
> WriteBooster feature can be available if below both conditions are satisf=
ied,
>=20
> 1. Device descriptor has dExtendedUFSFeaturesSupport field.
> 2. WriteBooster support is specified in above field.
>=20
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
>=20
> 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 *hb=
a)
>=20
>  static void ufshcd_wb_probe(struct ufs_hba *hba, u8 *desc_buf)  {
> +	if (hba->desc_size.dev_desc <=3D
> DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP)
> +		goto wb_disabled;
> +
>  	hba->dev_info.d_ext_ufs_feature_sup =3D
>  		get_unaligned_be32(desc_buf +
>=20
> 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 =3D
>  		desc_buf[DEVICE_DESC_PARAM_WB_PRESRV_USRSPC_EN];
>=20
> -	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 &=3D ~UFSHCD_CAP_WB_EN;
> +		goto wb_disabled;
> +
> +wb_disabled:
> +	hba->caps &=3D ~UFSHCD_CAP_WB_EN;
>  }
>=20
>  static int ufs_get_device_desc(struct ufs_hba *hba) @@ -6862,8 +6870,7 @=
@
> static int ufs_get_device_desc(struct ufs_hba *hba)
>=20
>  	model_index =3D desc_buf[DEVICE_DESC_PARAM_PRDCT_NAME];
>=20
> -	/* Enable WB only for UFS-3.1 */
> -	if (dev_info->wspecversion >=3D 0x310)
> +	if (ufshcd_is_wb_allowed(hba))
>  		ufshcd_wb_probe(hba, desc_buf);
>=20
>  	err =3D ufshcd_read_string_desc(hba, model_index,
> --
> 2.18.0

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