linux-kernel - RE: [RESEND PATCH v10 04/10] scsi: ufs: introduce UFSHCD_QUIRK_PRDT_BYTE

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Date:   Thu, 13 Aug 2020 06:51:13 +0530
From:   "Alim Akhtar" <alim.akhtar@...sung.com>
To:     "'Eric Biggers'" <ebiggers@...nel.org>
Cc:     <robh@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-scsi@...r.kernel.org>, <krzk@...nel.org>,
        <avri.altman@....com>, <martin.petersen@...cle.com>,
        <kwmad.kim@...sung.com>, <stanley.chu@...iatek.com>,
        <cang@...eaurora.org>, <linux-samsung-soc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <kishon@...com>
Subject: RE: [RESEND PATCH v10 04/10] scsi: ufs: introduce
 UFSHCD_QUIRK_PRDT_BYTE_GRAN quirk

Hi Eric,

> -----Original Message-----
> From: Eric Biggers <ebiggers@...nel.org>
> Sent: 12 August 2020 05:59
> To: Alim Akhtar <alim.akhtar@...sung.com>
> Cc: robh@...nel.org; devicetree@...r.kernel.org;
linux-scsi@...r.kernel.org;
> krzk@...nel.org; avri.altman@....com; martin.petersen@...cle.com;
> kwmad.kim@...sung.com; stanley.chu@...iatek.com;
> cang@...eaurora.org; linux-samsung-soc@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; kishon@...com
> Subject: Re: [RESEND PATCH v10 04/10] scsi: ufs: introduce
> UFSHCD_QUIRK_PRDT_BYTE_GRAN quirk
> 
> Hi Alim,
> 
> On Sat, Jun 13, 2020 at 08:17:00AM +0530, Alim Akhtar wrote:
> > Some UFS host controllers like Exynos uses granularities of PRDT
> > length and offset as bytes, whereas others uses actual segment count.
> >
> > Reviewed-by: Avri Altman <avri.altman@....com>
> > Signed-off-by: Kiwoong Kim <kwmad.kim@...sung.com>
> > Signed-off-by: Alim Akhtar <alim.akhtar@...sung.com>
> > ---
> >  drivers/scsi/ufs/ufshcd.c | 30 +++++++++++++++++++++++-------
> > drivers/scsi/ufs/ufshcd.h |  6 ++++++
> >  2 files changed, 29 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> > index ee30ed6cc805..ba093d0d0942 100644
> > --- a/drivers/scsi/ufs/ufshcd.c
> > +++ b/drivers/scsi/ufs/ufshcd.c
> > @@ -2151,8 +2151,14 @@ static int ufshcd_map_sg(struct ufs_hba *hba,
> struct ufshcd_lrb *lrbp)
> >  		return sg_segments;
> >
> >  	if (sg_segments) {
> > -		lrbp->utr_descriptor_ptr->prd_table_length =
> > -			cpu_to_le16((u16)sg_segments);
> > +
> > +		if (hba->quirks & UFSHCD_QUIRK_PRDT_BYTE_GRAN)
> > +			lrbp->utr_descriptor_ptr->prd_table_length =
> > +				cpu_to_le16((sg_segments *
> > +					sizeof(struct ufshcd_sg_entry)));
> > +		else
> > +			lrbp->utr_descriptor_ptr->prd_table_length =
> > +				cpu_to_le16((u16) (sg_segments));
> >
> >  		prd_table = (struct ufshcd_sg_entry *)lrbp->ucd_prdt_ptr;
> >
> > @@ -3500,11 +3506,21 @@ static void
> ufshcd_host_memory_configure(struct ufs_hba *hba)
> >
> 	cpu_to_le32(upper_32_bits(cmd_desc_element_addr));
> >
> >  		/* Response upiu and prdt offset should be in double words
*/
> > -		utrdlp[i].response_upiu_offset =
> > -			cpu_to_le16(response_offset >> 2);
> > -		utrdlp[i].prd_table_offset = cpu_to_le16(prdt_offset >> 2);
> > -		utrdlp[i].response_upiu_length =
> > -			cpu_to_le16(ALIGNED_UPIU_SIZE >> 2);
> > +		if (hba->quirks & UFSHCD_QUIRK_PRDT_BYTE_GRAN) {
> > +			utrdlp[i].response_upiu_offset =
> > +				cpu_to_le16(response_offset);
> > +			utrdlp[i].prd_table_offset =
> > +				cpu_to_le16(prdt_offset);
> > +			utrdlp[i].response_upiu_length =
> > +				cpu_to_le16(ALIGNED_UPIU_SIZE);
> > +		} else {
> > +			utrdlp[i].response_upiu_offset =
> > +				cpu_to_le16(response_offset >> 2);
> > +			utrdlp[i].prd_table_offset =
> > +				cpu_to_le16(prdt_offset >> 2);
> > +			utrdlp[i].response_upiu_length =
> > +				cpu_to_le16(ALIGNED_UPIU_SIZE >> 2);
> > +		}
> >
> >  		ufshcd_init_lrb(hba, &hba->lrb[i], i);
> >  	}
> 
> Isn't this patch missing an update to ufshcd_print_trs()?  It uses
> ->prd_table_length as the number of segments, not the number of bytes.
> 
prd_table_length will be populated before it reaches ufshcd_print_trs()
based on UFSHCD_QUIRK_PRDT_BYTE_GRAN.

> - Eric