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SubjectRE: [PATCH] usb: dwc3: xilinx: improve error handling for PM APIs
Date
> -----Original Message-----
> From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> Sent: Saturday, November 11, 2023 5:09 AM
> To: Mehta, Piyush <piyush.mehta@amd.com>
> Cc: gregkh@linuxfoundation.org; Simek, Michal <michal.simek@amd.com>;
> Thinh Nguyen <Thinh.Nguyen@synopsys.com>; linux-usb@vger.kernel.org;
> linux-kernel@vger.kernel.org; git (AMD-Xilinx) <git@amd.com>
> Subject: Re: [PATCH] usb: dwc3: xilinx: improve error handling for PM APIs
>
> On Wed, Nov 08, 2023, Piyush Mehta wrote:
> > Improve error handling for PM APIs in the dwc3_xlnx_probe function by
> > introducing devm_pm_runtime_enable and error label. Removed
> > unnecessary API pm_runtime_disable call in dwc3_xlnx_remove.
> >
> > Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
> > ---
> > drivers/usb/dwc3/dwc3-xilinx.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/dwc3-xilinx.c
> > b/drivers/usb/dwc3/dwc3-xilinx.c index 5b7e92f476de..9cf26e9a1c3d
> > 100644
> > --- a/drivers/usb/dwc3/dwc3-xilinx.c
> > +++ b/drivers/usb/dwc3/dwc3-xilinx.c
> > @@ -294,10 +294,15 @@ static int dwc3_xlnx_probe(struct
> > platform_device *pdev)
> >
> > pm_runtime_set_active(dev);
> > pm_runtime_enable(dev);
> > + ret = devm_pm_runtime_enable(dev);
>
> You just did pm_runtime_enable() right above, why
> devm_pm_runtime_enable() again?

This will fix in next version.
>
> > + if (ret < 0)
> > + goto err_pm_set_suspended;
> > +
> > pm_suspend_ignore_children(dev, false);
> > - pm_runtime_get_sync(dev);
> > + return pm_runtime_resume_and_get(dev);
> >
> > - return 0;
> > +err_pm_set_suspended:
> > + pm_runtime_set_suspended(dev);
>
> This doesn't look right. why set status suspended here?

Status is set to suspended in the exit path to undo the state
set by pm_runtime_set_active(). The initial runtime PM status of
all devices is 'suspended'.

There is a mention of in Documentation/power/runtime_pm.rst
For this reason, once pm_runtime_set_active() has been called for the device,
pm_runtime_enable() should be called for it too as soon as reasonably possible
or its run-time PM status should be changed back to 'suspended' with the help of
pm_runtime_set_suspended().

>
> BR,
> Thinh
>
> >
> > err_clk_put:
> > clk_bulk_disable_unprepare(priv_data->num_clocks, priv_data-
> >clks);
> > @@ -315,7 +320,6 @@ static void dwc3_xlnx_remove(struct
> platform_device *pdev)
> > clk_bulk_disable_unprepare(priv_data->num_clocks, priv_data-
> >clks);
> > priv_data->num_clocks = 0;
> >
> > - pm_runtime_disable(dev);
> > pm_runtime_put_noidle(dev);
> > pm_runtime_set_suspended(dev);
> > }
> > --
> > 2.25.1
> >
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