linux-kernel - RE: [PATCH v5 1/8] scsi: ufs: enable WriteBooster on some pre-3.1 UFS devices

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Message-ID: <1588602837.3197.32.camel@mtkswgap22>
Date:   Mon, 4 May 2020 22:33:57 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     Avri Altman <Avri.Altman@....com>
CC:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "alim.akhtar@...sung.com" <alim.akhtar@...sung.com>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "bvanassche@....org" <bvanassche@....org>,
        "andy.teng@...iatek.com" <andy.teng@...iatek.com>,
        "chun-hung.wu@...iatek.com" <chun-hung.wu@...iatek.com>,
        "kuohong.wang@...iatek.com" <kuohong.wang@...iatek.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "peter.wang@...iatek.com" <peter.wang@...iatek.com>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "beanhuo@...ron.com" <beanhuo@...ron.com>
Subject: RE: [PATCH v5 1/8] scsi: ufs: enable WriteBooster on some pre-3.1
 UFS devices

Hi Avri,

On Mon, 2020-05-04 at 10:37 +0000, Avri Altman wrote:
> > 
> >  static void ufshcd_wb_probe(struct ufs_hba *hba, u8 *desc_buf)
> >  {
> > +       if (!ufshcd_is_wb_allowed(hba))
> > +               return;
> > +
> > +       if (hba->desc_size.dev_desc <=
> > DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP)
> Should be 
> DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP + 4 

I think this description length check is redundant because the device
quirk shall be added only after WriteBooster supportat is confirmed in
attached UFS device. So I will remove this in next version.

> 
> > +               goto wb_disabled;
> > +
> >         hba->dev_info.d_ext_ufs_feature_sup =
> >                 get_unaligned_be32(desc_buf +
> >                                    DEVICE_DESC_PARAM_EXT_UFS_FEATURE_SUP);
> 
> 
> > 
> >  static int ufs_get_device_desc(struct ufs_hba *hba)
> > @@ -6862,10 +6890,6 @@ 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)
> > -               ufshcd_wb_probe(hba, desc_buf);
> > -
> >         err = ufshcd_read_string_desc(hba, model_index,
> >                                       &dev_info->model, SD_ASCII_STD);
> >         if (err < 0) {
> > @@ -6874,6 +6898,16 @@ static int ufs_get_device_desc(struct ufs_hba
> > *hba)
> >                 goto out;
> >         }
> > 
> > +       ufs_fixup_device_setup(hba);
> I don't think you should "hide" ufs_fixup_device_setup inside ufs_get_device_desc.

The reason is as below,

ufshcd_wb_probe() needs the contents of Device Descriptor for
initialization. To avoid double reading the Device Descriptor, I keep
ufshcd_wb_probe() inside ufs_get_device_desc() to use its "desc_buf".

And ufshcd_wb_probe() needs well-configured device quirk for entrance
check, thus ufs_fixup_device_setup() shall be moved before
ufshcd_wb_probe().

This change does not affect the behavior and functionality of
ufs_fixup_device_setup() since it is still executed once only during
ufshcd_init() flow and not be executed again in the future.

Thanks,
Stanley Chu

> 
> Thanks,
> Avri
> 
> _______________________________________________
> Linux-mediatek mailing list
> Linux-mediatek@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek

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