From: Bart Van Assche <bvanassche@acm.org>
To: Stanley Chu <stanley.chu@mediatek.com>,
linux-scsi@vger.kernel.org, martin.petersen@oracle.com,
avri.altman@wdc.com, alim.akhtar@samsung.com,
pedrom.sousa@synopsys.com, sthumma@codeaurora.org,
jejb@linux.ibm.com
Cc: linux-mediatek@lists.infradead.org,
linux-arm-kernel@lists.infradead.org, matthias.bgg@gmail.com,
evgreen@chromium.org, beanhuo@micron.com,
marc.w.gonzalez@free.fr, subhashj@codeaurora.org,
vivek.gautam@codeaurora.org, kuohong.wang@mediatek.com,
peter.wang@mediatek.com, chun-hung.wu@mediatek.com,
andy.teng@mediatek.com
Subject: Re: [PATCH v2 1/3] scsi: core: allow auto suspend override by low-level driver
Date: Thu, 12 Sep 2019 14:43:44 +0100 [thread overview]
Message-ID: <485731ed-d455-dbb2-0cd5-3110ff14f6b7@acm.org> (raw)
In-Reply-To: <1568270135-32442-2-git-send-email-stanley.chu@mediatek.com>
On 9/12/19 7:35 AM, Stanley Chu wrote:
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 64c96c7828ee..461aafadd208 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -1300,7 +1300,8 @@ int scsi_sysfs_add_sdev(struct scsi_device *sdev)
> device_enable_async_suspend(&sdev->sdev_gendev);
> scsi_autopm_get_target(starget);
> pm_runtime_set_active(&sdev->sdev_gendev);
> - pm_runtime_forbid(&sdev->sdev_gendev);
> + if (sdev->rpm_autosuspend_delay < 0)
> + pm_runtime_forbid(&sdev->sdev_gendev);
> pm_runtime_enable(&sdev->sdev_gendev);
> scsi_autopm_put_target(starget);
So we have a single new struct member, rpm_autosuspend_delay, that
controls two different behaviors: (a) whether or not runtime suspend is
enabled at device creation time and (b) the power management autosuspend
delay. I don't like this. Should two separate variables be introduced
instead of using a single variable to control both behaviors?
> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
> index 202f4d6a4342..133b282fae5a 100644
> --- a/include/scsi/scsi_device.h
> +++ b/include/scsi/scsi_device.h
> @@ -199,7 +199,7 @@ struct scsi_device {
> unsigned broken_fua:1; /* Don't set FUA bit */
> unsigned lun_in_cdb:1; /* Store LUN bits in CDB[1] */
> unsigned unmap_limit_for_ws:1; /* Use the UNMAP limit for WRITE SAME */
> -
> + int rpm_autosuspend_delay;
> atomic_t disk_events_disable_depth; /* disable depth for disk events */
>
> DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */
>
Since the default value for the autosuspend delay is the same for all
SCSI devices attached to a SCSI host is the same, please add a variable
with the same name in the SCSI host template and use that value as the
default value for SCSI devices. If the rpm_autosuspend_delay variable
only occurs in struct scsi_device then LLD authors are forced to
introduce a slave_configure function. Introducing such a function can be
avoided if the default autosuspend delay can be specified in the host
template.
Bart.
next prev parent reply other threads:[~2019-09-12 13:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-12 6:35 [PATCH v2] scsi: allow auto suspend override by low-level driver Stanley Chu
2019-09-12 6:35 ` [PATCH v2 1/3] scsi: core: " Stanley Chu
2019-09-12 13:43 ` Bart Van Assche [this message]
2019-09-16 6:38 ` Stanley Chu
2019-09-12 6:35 ` [PATCH v2 2/3] scsi: ufs: override auto suspend tunables for ufs Stanley Chu
2019-09-12 6:35 ` [PATCH v2 3/3] scsi: ufs-mediatek: enable auto suspend capability Stanley Chu
2019-09-12 13:46 ` Bart Van Assche
2019-09-16 6:29 ` Stanley Chu
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