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SubjectRe: [PATCH] bus: mhi: host: Disable preemption while processing data events
On Thu, Nov 03, 2022 at 03:55:11PM +0800, Qiang Yu wrote:
> If data processing of an event is scheduled out because core
> is busy handling multiple irqs, this can starves the processing

s/starves/starve

> 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@quicinc.com>
> ---
> drivers/bus/mhi/host/main.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
> index f3aef77a..b58698d 100644
> --- a/drivers/bus/mhi/host/main.c
> +++ b/drivers/bus/mhi/host/main.c
> @@ -1027,13 +1027,14 @@ int mhi_process_data_event_ring(struct mhi_controller *mhi_cntrl,
>
> void mhi_ev_task(unsigned long data)
> {
> + unsigned long flags;
> 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);

Please add a comment stating why we are disabling local IRQs here. This will
help in understanding the code better.

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
>
>

--
மணிவண்ணன் சதாசிவம்

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