[PATCH 0/1] usb: dwc3: meson-g12a: fix shared reset control use

[Anand Moon]

hi Dan,

On Mon, 13 Jul 2020 at 21:37, Dan Robertson <dan at dlrobertson.com> wrote:
>
> When testing suspend for another driver I noticed the following warning:
>
> WARNING: CPU: 1 PID: 5530 at drivers/reset/core.c:355 reset_control_assert+0x184/0x19c
> Hardware name: Hardkernel ODROID-N2 (DT)
> [..]
> pc : reset_control_assert+0x184/0x19c
> lr : dwc3_meson_g12a_suspend+0x68/0x7c
> [..]
> Call trace:
>  reset_control_assert+0x184/0x19c
>  dwc3_meson_g12a_suspend+0x68/0x7c
>  platform_pm_suspend+0x28/0x54
>  __device_suspend+0x590/0xabc
>  dpm_suspend+0x104/0x404
>  dpm_suspend_start+0x84/0x1bc
>  suspend_devices_and_enter+0xc4/0x4fc
>
> In my limited experience and knowlege it appears that we hit this
> because the reset control was switched to shared and the the use
> of the reset control was not changed.
>
> > * Calling reset_control_assert without first calling reset_control_deassert
> > * is not allowed on a shared reset control. Calling reset_control_reset is
> > * also not allowed on a shared reset control.
>
> The above snippet from reset_control_get_shared() seems to indicate that
> this is due to the use of reset_control_reset() in dwc3_meson_g12a_probe()
> and reset_control_deassert is not guaranteed to have been called
> before dwc3_meson_g12a_suspend() and reset_control_assert().
>
> After some basic tests with the following patch I no longer hit the
> warning. Comments and critiques on the patch are welcome. If there is a
> reason for the current use of the reset control, I'd love to learn why!
> Like I said before, I have not really looked at this driver before and
> have verify limited experience with reset controls... Was working on
> another driver, hit the warning, and thought I'd take a shot at the
> fix :-)
>
Thanks, I was also looking into this issue
So best Fix to this issue is to drop the call of reset_control_assert
from dwc3_meson_g12a_suspend
and drop the call of reset_control_deassert from dwc3_meson_g12a_resume
With these changes we do not see the warning on suspend and resume

Can you try this attached patch?

Best Regards
-Anand
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