Re: [PATCH v7 10/10] mhi: pci_generic: Set irq moderation value to 1ms for hw channels

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Jan 04, 2021 at 02:49:39PM +0100, Loic Poulain wrote:
> MHI hardware channels are usually the hardware accelerated data path
> e.g. IP packets path for modems. This path needs to be optimized for
> low latency and high throughput. After several tests on FN980m SDX55
> based modem, it seems 1ms is a good default irq_moderation value:
> 
> - It allows to reach the maximum download throughput
> - It introduces limited latency (5ms is too high)
> - It prevents interrupt flooding
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Thanks,
Mani

> ---
>  drivers/bus/mhi/pci_generic.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
> index a4b6221..1603c83 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -130,7 +130,7 @@ struct mhi_pci_dev_info {
>  #define MHI_EVENT_CONFIG_HW_DATA(ev_ring, ch_num) \
>  	{					\
>  		.num_elements = 256,		\
> -		.irq_moderation_ms = 5,		\
> +		.irq_moderation_ms = 1,		\
>  		.irq = (ev_ring) + 1,		\
>  		.priority = 1,			\
>  		.mode = MHI_DB_BRST_DISABLE,	\
> -- 
> 2.7.4
>