linux-kernel - RE: [PATCH v3 3/5] scsi: ufs: add LU Dedicated buffer mode support for WriteBooster

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Date:   Sun, 3 May 2020 14:06:16 +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>,
        "beanhuo@...ron.com" <beanhuo@...ron.com>,
        "cang@...eaurora.org" <cang@...eaurora.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "bvanassche@....org" <bvanassche@....org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kuohong.wang@...iatek.com" <kuohong.wang@...iatek.com>,
        "peter.wang@...iatek.com" <peter.wang@...iatek.com>,
        "chun-hung.wu@...iatek.com" <chun-hung.wu@...iatek.com>,
        "andy.teng@...iatek.com" <andy.teng@...iatek.com>
Subject: RE: [PATCH v3 3/5] scsi: ufs: add LU Dedicated buffer mode support
 for WriteBooster

Hi Avri,

On Sat, 2020-05-02 at 15:32 +0000, Avri Altman wrote:
> Hi Stanley,
> Few more nits.
> Thanks,
> Avri

All fixed in v4.
Thanks for these suggestions.

Stanley Chu

> 
> > 
> > According to UFS specification, there are two WriteBooster mode of
> > operations: "LU dedicated buffer" mode and "shared buffer" mode.
> > In the "LU dedicated buffer" mode, the WriteBooster Buffer is
> > dedicated to a logical unit.
> > 
> > If the device supports the "LU dedicated buffer" mode, this mode is
> > configured by setting bWriteBoosterBufferType to 00h. The logical
> > unit WriteBooster Buffer size is configured by setting the
> > dLUNumWriteBoosterBufferAllocUnits field of the related Unit
> > Descriptor. Only a value greater than zero enables the WriteBooster
> > feature in the logical unit.
> > 
> > Modify ufshcd_wb_probe() as above description to support LU Dedicated
> > buffer mode.
> > 
> > Note that according to UFS 3.1 specification, the valid value of
> > bDeviceMaxWriteBoosterLUs parameter in Geometry Descriptor is 1,
> > which means at most one LUN can have WriteBooster buffer in "LU
> > dedicated buffer mode". Therefore this patch supports only one
> > LUN with WriteBooster enabled. All WriteBooster related sysfs nodes
> > are specifically mapped to the LUN with WriteBooster enabled in
> > LU Dedicated buffer mode.
> > 
> > Signed-off-by: Stanley Chu <stanley.chu@...iatek.com>
> > ---
> >  drivers/scsi/ufs/ufs-sysfs.c | 14 ++++++++-
> >  drivers/scsi/ufs/ufs.h       |  7 +++++
> >  drivers/scsi/ufs/ufshcd.c    | 60 +++++++++++++++++++++++++++++-------
> >  drivers/scsi/ufs/ufshcd.h    |  1 +
> >  4 files changed, 70 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/scsi/ufs/ufs-sysfs.c b/drivers/scsi/ufs/ufs-sysfs.c
> > index b86b6a40d7e6..a162f63098e5 100644
> > --- a/drivers/scsi/ufs/ufs-sysfs.c
> > +++ b/drivers/scsi/ufs/ufs-sysfs.c
> > @@ -622,16 +622,28 @@ static const struct attribute_group
> > ufs_sysfs_string_descriptors_group = {
> >         .attrs = ufs_sysfs_string_descriptors,
> >  };
> > 
> > +static bool ufshcd_is_wb_flags(enum flag_idn idn)
> Inline?
> And just return (idn >= QUERY_FLAG_IDN_WB_EN &&  idn <= QUERY_FLAG_IDN_WB_BUFF_FLUSH_DURING_HIBERN8)
> 
> > +{
> > +       if (idn >= QUERY_FLAG_IDN_WB_EN &&
> > +           idn <= QUERY_FLAG_IDN_WB_BUFF_FLUSH_DURING_HIBERN8)
> > +               return true;
> > +       else
> > +               return false;
> > +}
> > +
> 
> 
> > 
> > +int ufshcd_wb_get_flag_index(struct ufs_hba *hba)
> > +{
> > +       if (hba->dev_info.b_wb_buffer_type ==
> > WB_BUF_MODE_LU_DEDICATED)
> > +               return hba->dev_info.wb_dedicated_lu;
> > +       else
> No need for else.
> Maybe make this static inline in ufshcd.h?
> 
> > +               return 0;
> > +}
> > +