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SubjectRe: [PATCH] usb: host: xhci-mtk: avoid runtime suspend when removing hcd
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On 29.5.2020 7.29, Macpaul Lin wrote:
> When runtime suspend was enabled, runtime suspend might happened
> when xhci is removing hcd. This might cause kernel panic when hcd
> has been freed but runtime pm suspend related handle need to
> reference it.
>
> Change-Id: I70a5dc8006207caeecbac6955ce8e5345dcc70e6
> Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
> ---
> drivers/usb/host/xhci-mtk.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-mtk.c b/drivers/usb/host/xhci-mtk.c
> index bfbdb3c..641d24e 100644
> --- a/drivers/usb/host/xhci-mtk.c
> +++ b/drivers/usb/host/xhci-mtk.c
> @@ -587,6 +587,9 @@ static int xhci_mtk_remove(struct platform_device *dev)
> struct xhci_hcd *xhci = hcd_to_xhci(hcd);
> struct usb_hcd *shared_hcd = xhci->shared_hcd;
>
> + pm_runtime_put_sync(&dev->dev);

Might runtime suspend here.
It's a lot better than before, no panic as hcd isn't released, but a bit unnecessary.

how about this sequence instead:
pm_runtime_disable()
pm_runtime_put_noidle()

> + pm_runtime_disable(&dev->dev);
> +

-Mathias

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