On Tue, Nov 15, 2022 at 10:23:51AM +0800, Qiang Yu wrote:
> If data processing of an event is scheduled out because core
> is busy handling multiple irqs, this can starve the processing
> of MHI M0 state change event on another core. Fix this issue by
> disabling irq on the core processing data events.
>
> Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
> ---
> v2->v3: modify the comment
> v1->v2: add comments about why we disable local irq
>
> drivers/bus/mhi/host/main.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index f3aef77a..5dca0a0 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -1027,13 +1027,20 @@ int mhi_process_data_event_ring(struct mhi_controller *mhi_cntrl,
>
> void mhi_ev_task(unsigned long data)
> {
> + unsigned long flags;
Reverse X-Mas tree order please. Move this definition to the last.
> struct mhi_event *mhi_event = (struct mhi_event *)data;
> struct mhi_controller *mhi_cntrl = mhi_event->mhi_cntrl;
>
> /* process all pending events */
> - spin_lock_bh(&mhi_event->lock);
> + spin_lock_irqsave(&mhi_event->lock, flags);
> + /*
> + * When multiple IRQs come, the tasklet will be scheduled out with event ring lock
s/come/arrive
> + * remaining acquired, causing M0 event process on another core gets stuck when it
s/remaining//
"causing other high priority events like M0 state transition getting stuck
while trying to acquire the same event ring lock."
> + * tries to acquire the same event ring lock. Thus, let's disable local IRQs here.
> + */
This comment should be placed above spin_lock_irqsave().
The comment "process all pending events" can be moved here.
Thanks,
Mani
> +
> mhi_event->process_event(mhi_cntrl, mhi_event, U32_MAX);
> - spin_unlock_bh(&mhi_event->lock);
> + spin_unlock_irqrestore(&mhi_event->lock, flags);
> }
>
> void mhi_ctrl_ev_task(unsigned long data)
> --
> 2.7.4
>
>
--
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