RE: RE: [PATCH v22 4/4] scsi: ufs: Add HPB 2.0 support

From: Daejun Park <daejun7.park@samsung.com>
To: Avri Altman <Avri.Altman@wdc.com>,
	Daejun Park <daejun7.park@samsung.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	"jejb@linux.ibm.com" <jejb@linux.ibm.com>,
	"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
	"asutoshd@codeaurora.org" <asutoshd@codeaurora.org>,
	"stanley.chu@mediatek.com" <stanley.chu@mediatek.com>,
	"cang@codeaurora.org" <cang@codeaurora.org>,
	"bvanassche@acm.org" <bvanassche@acm.org>,
	"huobean@gmail.com" <huobean@gmail.com>,
	ALIM AKHTAR <alim.akhtar@samsung.com>,
	Javier Gonzalez <javier.gonz@samsung.com>
Cc: "linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	JinHwan Park <jh.i.park@samsung.com>,
	SEUNGUK SHIN <seunguk.shin@samsung.com>,
	Sung-Jun Park <sungjun07.park@samsung.com>,
	yongmyung lee <ymhungry.lee@samsung.com>,
	Jinyoung CHOI <j-young.choi@samsung.com>,
	BoRam Shin <boram.shin@samsung.com>
Subject: RE: RE: [PATCH v22 4/4] scsi: ufs: Add HPB 2.0 support
Date: Tue, 23 Feb 2021 17:04:10 +0900	[thread overview]
Message-ID: <20210223080410epcms2p4704a20bb74cbbc1c1d0af92386eda2c7@epcms2p4> (raw)
In-Reply-To: <DM6PR04MB657588F1C76DC0D5BFC68862FC819@DM6PR04MB6575.namprd04.prod.outlook.com>

> > @@ -7447,8 +7452,14 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
> > 
> >         if (dev_info->wspecversion >= UFS_DEV_HPB_SUPPORT_VERSION &&
> >             (b_ufs_feature_sup & UFS_DEV_HPB_SUPPORT)) {
> > -               dev_info->hpb_enabled = true;
> > -               ufshpb_get_dev_info(hba, desc_buf);
> > +               bool hpb_en = false;
> > +
> > +               err = ufshcd_query_flag_retry(hba,
> > UPIU_QUERY_OPCODE_READ_FLAG,
> > +                                             QUERY_FLAG_IDN_HPB_EN, 0, &hpb_en);
> > +               if (!err && hpb_en) {
> > +                       dev_info->hpb_enabled = true;
> > +                       ufshpb_get_dev_info(hba, desc_buf);
> QUERY_FLAG_IDN_HPB_EN only apply to HPB2.0

OK,

> > +               }
> >         }
> > 
> > +
> > +/*
> > + * WRITE_BUFFER CMD support 36K (len=9) ~ 512K (len=128) default.
> > + * it is possible to change range of transfer_len through sysfs.
> > + */
> Actually the transfer length is limited by its (and read id) single byte.
> Fixing MAX_HPB_READ_ID = 128  is IMO a reasonable choice,
> But not limited by spec.  Maybe make note of that ?
>  
> > +static inline bool ufshpb_is_required_wb(struct ufshpb_lu *hpb, int len)
> > +{
> > +       return (len >= hpb->pre_req_min_tr_len &&
> > +               len <= hpb->pre_req_max_tr_len);
> >  }
> Maybe also check HPB2.0 as well?

OK,

> > -void ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
> > +int ufshpb_prep(struct ufs_hba *hba, struct ufshcd_lrb *lrbp)
> >  {
> >         struct ufshpb_lu *hpb;
> >         struct ufshpb_region *rgn;
> > @@ -282,26 +546,27 @@ void ufshpb_prep(struct ufs_hba *hba, struct
> > ufshcd_lrb *lrbp)
> >         u64 ppn;
> >         unsigned long flags;
> >         int transfer_len, rgn_idx, srgn_idx, srgn_offset;
> > +       int read_id = MAX_HPB_READ_ID;
> Should be 0 if wb is not used?

I will fix it.

> > +
> > +       hpb->pre_req = kcalloc(qd, sizeof(struct ufshpb_req), GFP_KERNEL);
> > +       hpb->throttle_pre_req = qd;
> What is the point in throttling if you are allowing 32 simultaneous commands?
> There can't be more than qd/2 anyway?
> On the contrary, it makes much more sense to control the inflight map requests, instead?

OK, I will change it to qd/2.

> > +       hpb->num_inflight_pre_req = 0;
> > +
>  
> > -#define HPB_SUPPORT_VERSION                    0x100
> > +#define HPB_SUPPORT_VERSION                    0x200
> In ufshpb_get_dev_info you are bailing out if version != HPB_SUPPORT_VERSION
> Meaning you are no longer backward supporting HPB1.0?

I add to support legacy version of HPB.

Thanks,
Daejun