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    Subject[PATCH 5.10 167/221] drm/msm: Fix suspend/resume on i.MX5
    Date
    From: Fabio Estevam <festevam@gmail.com>

    [ Upstream commit a9748134ea4aad989e52a6a91479e0acfd306e5b ]

    When putting iMX5 into suspend, the following flow is
    observed:

    [ 70.023427] [<c07755f0>] (msm_atomic_commit_tail) from [<c06e7218>]
    (commit_tail+0x9c/0x18c)
    [ 70.031890] [<c06e7218>] (commit_tail) from [<c0e2920c>]
    (drm_atomic_helper_commit+0x1a0/0x1d4)
    [ 70.040627] [<c0e2920c>] (drm_atomic_helper_commit) from
    [<c06e74d4>] (drm_atomic_helper_disable_all+0x1c4/0x1d4)
    [ 70.050913] [<c06e74d4>] (drm_atomic_helper_disable_all) from
    [<c0e2943c>] (drm_atomic_helper_suspend+0xb8/0x170)
    [ 70.061198] [<c0e2943c>] (drm_atomic_helper_suspend) from
    [<c06e84bc>] (drm_mode_config_helper_suspend+0x24/0x58)

    In the i.MX5 case, priv->kms is not populated (as i.MX5 does not use any
    of the Qualcomm display controllers), causing a NULL pointer
    dereference in msm_atomic_commit_tail():

    [ 24.268964] 8<--- cut here ---
    [ 24.274602] Unable to handle kernel NULL pointer dereference at
    virtual address 00000000
    [ 24.283434] pgd = (ptrval)
    [ 24.286387] [00000000] *pgd=ca212831
    [ 24.290788] Internal error: Oops: 17 [#1] SMP ARM
    [ 24.295609] Modules linked in:
    [ 24.298777] CPU: 0 PID: 197 Comm: init Not tainted 5.11.0-rc2-next-20210111 #333
    [ 24.306276] Hardware name: Freescale i.MX53 (Device Tree Support)
    [ 24.312442] PC is at msm_atomic_commit_tail+0x54/0xb9c
    [ 24.317743] LR is at commit_tail+0xa4/0x1b0

    Fix the problem by calling drm_mode_config_helper_suspend/resume()
    only when priv->kms is available.

    Fixes: ca8199f13498 ("drm/msm/dpu: ensure device suspend happens during PM sleep")
    Signed-off-by: Fabio Estevam <festevam@gmail.com>
    Signed-off-by: Rob Clark <robdclark@chromium.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/gpu/drm/msm/msm_drv.c | 8 ++++++++
    1 file changed, 8 insertions(+)

    diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
    index 45e325c982c2..b38ebccad42f 100644
    --- a/drivers/gpu/drm/msm/msm_drv.c
    +++ b/drivers/gpu/drm/msm/msm_drv.c
    @@ -1079,6 +1079,10 @@ static int __maybe_unused msm_pm_resume(struct device *dev)
    static int __maybe_unused msm_pm_prepare(struct device *dev)
    {
    struct drm_device *ddev = dev_get_drvdata(dev);
    + struct msm_drm_private *priv = ddev ? ddev->dev_private : NULL;
    +
    + if (!priv || !priv->kms)
    + return 0;

    return drm_mode_config_helper_suspend(ddev);
    }
    @@ -1086,6 +1090,10 @@ static int __maybe_unused msm_pm_prepare(struct device *dev)
    static void __maybe_unused msm_pm_complete(struct device *dev)
    {
    struct drm_device *ddev = dev_get_drvdata(dev);
    + struct msm_drm_private *priv = ddev ? ddev->dev_private : NULL;
    +
    + if (!priv || !priv->kms)
    + return;

    drm_mode_config_helper_resume(ddev);
    }
    --
    2.30.1


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