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    SubjectRe: [PATCH v4 14/79] media: am437x: fix pm_runtime_get_sync() usage count
    On Wed, 28 Apr 2021 16:51:35 +0200
    Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:

    > The pm_runtime_get_sync() internally increments the
    > dev->power.usage_count without decrementing it, even on errors.
    > Replace it by the new pm_runtime_resume_and_get(), introduced by:
    > commit dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter")
    > in order to properly decrement the usage counter and avoid memory
    > leaks.
    >
    > While here, ensure that the driver will check if PM runtime
    > resumed at vpfe_initialize_device().
    >
    > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

    resume and suspend carrying regardless needs a comment I think.
    (see below)
    > ---
    > drivers/media/platform/am437x/am437x-vpfe.c | 22 +++++++++++++++------
    > 1 file changed, 16 insertions(+), 6 deletions(-)
    >
    > diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
    > index 6cdc77dda0e4..bced526f30f2 100644
    > --- a/drivers/media/platform/am437x/am437x-vpfe.c
    > +++ b/drivers/media/platform/am437x/am437x-vpfe.c
    > @@ -1021,7 +1021,9 @@ static int vpfe_initialize_device(struct vpfe_device *vpfe)
    > if (ret)
    > return ret;
    >
    > - pm_runtime_get_sync(vpfe->pdev);
    > + ret = pm_runtime_resume_and_get(vpfe->pdev);
    > + if (ret < 0)
    > + return ret;
    >
    > vpfe_config_enable(&vpfe->ccdc, 1);
    >
    > @@ -2443,7 +2445,11 @@ static int vpfe_probe(struct platform_device *pdev)
    > pm_runtime_enable(&pdev->dev);
    >
    > /* for now just enable it here instead of waiting for the open */
    > - pm_runtime_get_sync(&pdev->dev);
    > + ret = pm_runtime_resume_and_get(&pdev->dev);
    > + if (ret < 0) {
    > + vpfe_err(vpfe, "Unable to resume device.\n");
    > + goto probe_out_v4l2_unregister;
    > + }
    >
    > vpfe_ccdc_config_defaults(ccdc);
    >
    > @@ -2527,10 +2533,11 @@ static int vpfe_suspend(struct device *dev)
    > {
    > struct vpfe_device *vpfe = dev_get_drvdata(dev);
    > struct vpfe_ccdc *ccdc = &vpfe->ccdc;
    > + int ret;
    >
    > /* only do full suspend if streaming has started */
    > if (vb2_start_streaming_called(&vpfe->buffer_queue)) {
    > - pm_runtime_get_sync(dev);
    > + ret = pm_runtime_resume_and_get(dev);

    Carrying on when you know the resume failed, seems interesting enough to
    deserve a comment in the code. Not sure you can usefully do anything
    but it seems likely a lot of the calls that follow will fail.


    > vpfe_config_enable(ccdc, 1);
    >
    > /* Save VPFE context */
    > @@ -2541,7 +2548,8 @@ static int vpfe_suspend(struct device *dev)
    > vpfe_config_enable(ccdc, 0);
    >
    > /* Disable both master and slave clock */
    > - pm_runtime_put_sync(dev);
    > + if (ret >= 0)
    > + pm_runtime_put_sync(dev);
    > }
    >
    > /* Select sleep pin state */
    > @@ -2583,18 +2591,20 @@ static int vpfe_resume(struct device *dev)
    > {
    > struct vpfe_device *vpfe = dev_get_drvdata(dev);
    > struct vpfe_ccdc *ccdc = &vpfe->ccdc;
    > + int ret;
    >
    > /* only do full resume if streaming has started */
    > if (vb2_start_streaming_called(&vpfe->buffer_queue)) {
    > /* Enable both master and slave clock */
    > - pm_runtime_get_sync(dev);
    > + ret = pm_runtime_resume_and_get(dev);
    > vpfe_config_enable(ccdc, 1);
    >
    > /* Restore VPFE context */
    > vpfe_restore_context(ccdc);
    >
    > vpfe_config_enable(ccdc, 0);
    > - pm_runtime_put_sync(dev);
    > + if (ret >= 0)
    > + pm_runtime_put_sync(dev);
    > }
    >
    > /* Select default pin state */

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