linux-kernel - RE: [PATCH] scsi: ufs: Allow async suspend/resume callbacks

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Date:   Fri, 30 Jul 2021 18:17:00 +0000
From:   Avri Altman <Avri.Altman@....com>
To:     Bart Van Assche <bvanassche@....org>,
        Vincent Palomares <paillon@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>
CC:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Jaegeuk Kim <jaegeuk@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Can Guo <cang@...eaurora.org>,
        Asutosh Das <asutoshd@...eaurora.org>,
        "Martin K . Petersen" <martin.petersen@...cle.com>
Subject: RE: [PATCH] scsi: ufs: Allow async suspend/resume callbacks

> On 7/28/21 11:48 PM, Avri Altman wrote:
> > Vincent wrote:
> >> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> >> index b87ff68aa9aa..9ec5c308a0ea 100644
> >> --- a/drivers/scsi/ufs/ufshcd.c
> >> +++ b/drivers/scsi/ufs/ufshcd.c
> >> @@ -9625,6 +9625,7 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem
> >> *mmio_base, unsigned int irq)
> >>          async_schedule(ufshcd_async_scan, hba);
> >>          ufs_sysfs_add_nodes(hba->dev);
> >>
> >> +       device_enable_async_suspend(dev);
> >>          return 0;
> > Isn't device_enable_async_suspend is being called for each lun in
> scsi_sysfs_add_sdev Anyway?
> 
> Hi Avri,
> 
> Our measurements have shown that resume takes longer than it should with
> encryption enabled. While suspending we change the power mode of the UFS
> device to a mode in which it loses crypto keys. Restoring crypto keys
> during resume (blk_ksm_reprogram_all_keys()) takes about 31 ms. This is
> the long pole and takes much more time than resuming LUNs. This patch
> makes UFS resume happen concurrently with resuming other devices in the
> system instead of serializing it. Measurements have shown that this
> patch significantly improves the time needed to resume an Android device.
OK.
Thanks for the extra info.

Thanks,
Avri

> 
> Bart.