linux-kernel - RE: RE: [PATCH v22 3/4] scsi: ufs: Prepare HPB read for cached sub-region

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Date:   Wed, 24 Feb 2021 08:38:09 +0900
From:   Daejun Park <daejun7.park@...sung.com>
To:     Avri Altman <Avri.Altman@....com>,
        Daejun Park <daejun7.park@...sung.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        "jejb@...ux.ibm.com" <jejb@...ux.ibm.com>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "asutoshd@...eaurora.org" <asutoshd@...eaurora.org>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "bvanassche@....org" <bvanassche@....org>,
        "huobean@...il.com" <huobean@...il.com>,
        ALIM AKHTAR <alim.akhtar@...sung.com>,
        Javier Gonzalez <javier.gonz@...sung.com>
CC:     "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        JinHwan Park <jh.i.park@...sung.com>,
        SEUNGUK SHIN <seunguk.shin@...sung.com>,
        Sung-Jun Park <sungjun07.park@...sung.com>,
        yongmyung lee <ymhungry.lee@...sung.com>,
        Jinyoung CHOI <j-young.choi@...sung.com>,
        BoRam Shin <boram.shin@...sung.com>
Subject: RE: RE: [PATCH v22 3/4] scsi: ufs: Prepare HPB read for cached
 sub-region

> > +static int ufshpb_fill_ppn_from_page(struct ufshpb_lu *hpb,
> > +                                    struct ufshpb_map_ctx *mctx, int pos,
> > +                                    int len, u64 *ppn_buf)
> > +{
> > +       struct page *page;
> > +       int index, offset;
> > +       int copied;
> > +
> > +       index = pos / (PAGE_SIZE / HPB_ENTRY_SIZE);
> > +       offset = pos % (PAGE_SIZE / HPB_ENTRY_SIZE);
> Maybe cache hpb->entries_per_page in ufshpb_lu_parameter_init as well?

They are just defined constants and complier will optimize them.

Thanks,
Daejun

> > +
> > +       if ((offset + len) <= (PAGE_SIZE / HPB_ENTRY_SIZE))
> > +               copied = len;
> > +       else
> > +               copied = (PAGE_SIZE / HPB_ENTRY_SIZE) - offset;
> > +
> > +       page = mctx->m_page[index];
> > +       if (unlikely(!page)) {
> > +               dev_err(&hpb->sdev_ufs_lu->sdev_dev,
> > +                       "error. cannot find page in mctx\n");
> > +               return -ENOMEM;
> > +       }
> > +
> > +       memcpy(ppn_buf, page_address(page) + (offset * HPB_ENTRY_SIZE),
> > +              copied * HPB_ENTRY_SIZE);
> > +
> > +       return copied;
> > +}
>  
>  
>