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Message-ID: <2f0141705b06339d31063c731b0511fc186364fd.camel@iokpp.de>
Subject: Re: [PATCH v4 2/3] scsi: ufs: core: Cleanup ufshcd_slave_alloc()
From:   Bean Huo <beanhuo@iokpp.de>
To:     Bart Van Assche <bvanassche@acm.org>, alim.akhtar@samsung.com,
        avri.altman@wdc.com, asutoshd@codeaurora.org, jejb@linux.ibm.com,
        martin.petersen@oracle.com, stanley.chu@mediatek.com,
        beanhuo@micron.com, tomas.winkler@intel.com, cang@codeaurora.org,
        daejun7.park@samsung.com
Cc:     linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 25 Oct 2022 13:44:18 +0200
In-Reply-To: <1915c52f-0c76-0f90-97e9-0c27c36a9e1a@acm.org>
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         <20221022213650.626766-3-beanhuo@iokpp.de>
         <1915c52f-0c76-0f90-97e9-0c27c36a9e1a@acm.org>
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On Mon, 2022-10-24 at 16:25 -0700, Bart Van Assche wrote:
> On 10/22/22 14:36, Bean Huo wrote:
> > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0u8 lun_qdepth =3D hba->nutrs=
;
>=20
> How about changing this into hba->nutrs - 1 since one tag is reserved
> ('reserved_slot')?
>=20
> Thanks,


Bart,

If having a look at=C2=A0

scsi_change_queue_depth() {

  depth =3D min_t(int, depth, scsi_device_max_queue_depth(sdev));
	...
}

so the finnal depth per Lu is still 31.  I did test and debug, this is
true.


+set_qdepth:
+	/*
+	 * For WLUNs that don't support unit descriptor, queue depth
is set to 1. For LUs whose
+	 * bLUQueueDepth =3D=3D 0, the queue depth is set to a maximum
value that host can queue.
+	 */
+	dev_dbg(hba->dev, "Set LU %x queue depth %d\n", lun,
lun_qdepth);
+	scsi_change_queue_depth(sdev, lun_qdepth);=20


so lun_qdepth is 32, but scsi_change_queue_depth() will return 31,
since we set sdev->host->can_queue is 31.

If you need me to change the patch, let me know, it is no problem for
me to change to:=20


u8 lun_qdepth =3D hba->nutrs - UFSHCD_NUM_RESERVED.

or

u8 lun_qdepth =3D UFSHCD_CMD_PER_LUN.


Kind regards,
Bean