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    Subject[PATCH 3.16 70/87] scsi: ufs: Avoid runtime suspend possibly being blocked forever
    3.16.75-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Stanley Chu <stanley.chu@mediatek.com>

    commit 24e2e7a19f7e4b83d0d5189040d997bce3596473 upstream.

    UFS runtime suspend can be triggered after pm_runtime_enable() is invoked
    in ufshcd_pltfrm_init(). However if the first runtime suspend is triggered
    before binding ufs_hba structure to ufs device structure via
    platform_set_drvdata(), then UFS runtime suspend will be no longer
    triggered in the future because its dev->power.runtime_error was set in the
    first triggering and does not have any chance to be cleared.

    To be more clear, dev->power.runtime_error is set if hba is NULL in
    ufshcd_runtime_suspend() which returns -EINVAL to rpm_callback() where
    dev->power.runtime_error is set as -EINVAL. In this case, any future
    rpm_suspend() for UFS device fails because rpm_check_suspend_allowed()
    fails due to non-zero
    dev->power.runtime_error.

    To resolve this issue, make sure the first UFS runtime suspend get valid
    "hba" in ufshcd_runtime_suspend(): Enable UFS runtime PM only after hba is
    successfully bound to UFS device structure.

    Fixes: 62694735ca95 ([SCSI] ufs: Add runtime PM support for UFS host controller driver)
    Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
    Reviewed-by: Avri Altman <avri.altman@wdc.com>
    Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
    [bwh: Backported to 3.16:
    - ufshcd_pltrfm_probe() doesn't allocate or free the host structure
    - Adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/scsi/ufs/ufshcd-pltfrm.c | 11 ++++-------
    1 file changed, 4 insertions(+), 7 deletions(-)

    --- a/drivers/scsi/ufs/ufshcd-pltfrm.c
    +++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
    @@ -150,22 +150,19 @@ static int ufshcd_pltfrm_probe(struct pl
    goto out;
    }

    - pm_runtime_set_active(&pdev->dev);
    - pm_runtime_enable(&pdev->dev);
    -
    err = ufshcd_init(dev, &hba, mmio_base, irq);
    if (err) {
    dev_err(dev, "Intialization failed\n");
    - goto out_disable_rpm;
    + goto out;
    }

    platform_set_drvdata(pdev, hba);

    + pm_runtime_set_active(&pdev->dev);
    + pm_runtime_enable(&pdev->dev);
    +
    return 0;

    -out_disable_rpm:
    - pm_runtime_disable(&pdev->dev);
    - pm_runtime_set_suspended(&pdev->dev);
    out:
    return err;
    }
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