Re: [PATCH] bus: mhi: core: Allow shared IRQ for event rings

[bbhatt@codeaurora.org]

On 2020-09-18 00:28, Loic Poulain wrote:
> There is no requirement for using a dedicated IRQ per event ring.
> Some systems does not support multiple MSI vectors (e.g. intel
> without CONFIG_IRQ_REMAP), In that case the MHI controller can
> configure all the event rings to use the same interrupt (as fallback).
> 
> Allow this by removing the nr_irqs = ev_ring test and add extra check
> in the irq_setup function.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
>  drivers/bus/mhi/core/init.c | 10 ++++++++++
>  drivers/bus/mhi/core/pm.c   |  3 ---
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
> index d232938..ac19067 100644
> --- a/drivers/bus/mhi/core/init.c
> +++ b/drivers/bus/mhi/core/init.c
> @@ -113,6 +113,9 @@ int mhi_init_irq_setup(struct mhi_controller 
> *mhi_cntrl)
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
>  	int i, ret;
> 
> +	if (mhi_cntrl->nr_irqs < 1)
> +		return -EINVAL;
> +

It would be better to move this check earlier in 
mhi_register_controller() because if
the resource is not available, we do not have to proceed to even allow 
power up.

>  	/* Setup BHI_INTVEC IRQ */
>  	ret = request_threaded_irq(mhi_cntrl->irq[0], mhi_intvec_handler,
>  				   mhi_intvec_threaded_handler,
> @@ -125,6 +128,13 @@ int mhi_init_irq_setup(struct mhi_controller 
> *mhi_cntrl)
>  		if (mhi_event->offload_ev)
>  			continue;
> 
> +		if (mhi_event->irq >= mhi_cntrl->nr_irqs) {
> +			dev_err(dev, "irq %d not available for event ring\n",
> +				mhi_event->irq);
> +			ret = -EINVAL;
> +			goto error_request;
> +		}
> +
>  		ret = request_irq(mhi_cntrl->irq[mhi_event->irq],
>  				  mhi_irq_handler,
>  				  IRQF_SHARED | IRQF_NO_SUSPEND,
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index ce4d969..07efdbc 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -918,9 +918,6 @@ int mhi_async_power_up(struct mhi_controller 
> *mhi_cntrl)
> 
>  	dev_info(dev, "Requested to power ON\n");
> 
> -	if (mhi_cntrl->nr_irqs < mhi_cntrl->total_ev_rings)
> -		return -EINVAL;
> -
>  	/* Supply default wake routines if not provided by controller driver 
> */
>  	if (!mhi_cntrl->wake_get || !mhi_cntrl->wake_put ||
>  	    !mhi_cntrl->wake_toggle) {

Maybe another clean-up patch is also good to remove usage of 
"mhi_cntrl->nr_irqs_req"
as it is deemed optional anyway and is unused in the driver.

Thanks,
Bhaumik

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