On Wed, Mar 14, 2018 at 11:06:02PM +0100, Hans de Goede wrote:
> This reverts commit 43fff7683468 ("Bluetooth: hci_bcm: Streamline runtime
> PM code"). The commit msg for this commit states "No functional change
> intended.", but replacing:
>
> pm_runtime_get();
> pm_runtime_mark_last_busy();
> pm_runtime_put_autosuspend();
>
> with:
>
> pm_request_resume();
>
> Does result in a functional change, pm_request_resume() only calls
> pm_runtime_mark_last_busy() if the device was suspended before the call.
>
> This results in the following happening:
>
> 1) Device is runtime suspended
> 2) Device drives host_wake IRQ logically high as it starts receiving data
> 3) bcm_host_wake() gets called, causes the device to runtime-resume,
> current time gets marked as last_busy time
> 4) After 5 seconds the autosuspend timer expires and the dev autosuspends
> as no one has been calling pm_runtime_mark_last_busy(), the device was
> resumed during those 5 seconds, so all the pm_request_resume() calls
> while receiving data and/or bcm_host_wake() calls were nops
> 5) If 4) happens while the device has (just received) data in its buffer to
> be read by the host the IRQ line is *already* / still logically high
> when we autosuspend and since we use an edge triggered IRQ, the IRQ
> will never trigger, causing the device to get stuck in suspend
>
> Therefor this commit has to be reverted, so that we avoid the device
> getting stuck in suspend.
>
> Cc: Lukas Wunner <lukas@xxxxxxxxx>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Acked-by: Lukas Wunner <lukas@xxxxxxxxx>
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