Re: [PATCH 3/8] mhi: pci_generic: Enable burst mode for hardware channels

[Bhaumik Bhatt <bbhatt@codeaurora.org>]

Hi Loic,
On 2020-11-13 06:59, Loic Poulain wrote:
> Hardware channels have a feature called burst mode that allows to
> queue transfer ring element(s) (TRE) to a channel without ringing
> the device doorbell. In that mode, the device is polling the channel
> context for new elements. This reduces the frequency of host initiated
> doorbells and increase throughput.
> 
> Create a new dedicated macro for hardware channels with burst enabled.
> 
> Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
> ---
>  drivers/bus/mhi/pci_generic.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/bus/mhi/pci_generic.c 
> b/drivers/bus/mhi/pci_generic.c
> index 09c6b26..0c07cf5 100644
> --- a/drivers/bus/mhi/pci_generic.c
> +++ b/drivers/bus/mhi/pci_generic.c
> @@ -78,6 +78,36 @@ struct mhi_pci_dev_info {
>  		.offload_channel = false,	\
>  	}
> 
> +#define MHI_CHANNEL_CONFIG_HW_UL(ch_num, ch_name, el_count, ev_ring) \
> +	{						\
> +		.num = ch_num,				\
> +		.name = ch_name,			\
> +		.num_elements = el_count,		\
> +		.event_ring = ev_ring,			\
> +		.dir = DMA_TO_DEVICE,			\
> +		.ee_mask = BIT(MHI_EE_AMSS),		\
> +		.pollcfg = 0,				\
> +		.doorbell = MHI_DB_BRST_ENABLE,	\
> +		.lpm_notify = false,			\
> +		.offload_channel = false,		\
> +		.doorbell_mode_switch = false,		\
doorbell_mode_switch should be true for channel 100 (UL). Any reason why 
the boolean
fields are not yet configurable from the parameters to this macro? That 
will be
needed going forward so it should be changed now.

doorbell also may not be "enabled" by default. Basically, let's have 
something that
can be easily configured for different kinds of HW channels.
> +	}						\
> +
> +#define MHI_CHANNEL_CONFIG_HW_DL(ch_num, ch_name, el_count, ev_ring) \
> +	{						\
> +		.num = ch_num,				\
> +		.name = ch_name,			\
> +		.num_elements = el_count,		\
> +		.event_ring = ev_ring,			\
> +		.dir = DMA_FROM_DEVICE,			\
> +		.ee_mask = BIT(MHI_EE_AMSS),		\
> +		.pollcfg = 0,				\
> +		.doorbell = MHI_DB_BRST_ENABLE,	\
> +		.lpm_notify = false,			\
> +		.offload_channel = false,		\
> +		.doorbell_mode_switch = false,		\
> +	}
> +
>  #define MHI_EVENT_CONFIG_DATA(ev_ring)		\
>  	{					\
>  		.num_elements = 128,		\
> @@ -112,8 +142,8 @@ static const struct mhi_channel_config
> modem_qcom_v1_mhi_channels[] = {
>  	MHI_CHANNEL_CONFIG_DL(15, "QMI", 4, 0),
>  	MHI_CHANNEL_CONFIG_UL(20, "IPCR", 8, 0),
>  	MHI_CHANNEL_CONFIG_DL(21, "IPCR", 8, 0),
> -	MHI_CHANNEL_CONFIG_UL(100, "IP_HW0", 128, 1),
> -	MHI_CHANNEL_CONFIG_DL(101, "IP_HW0", 128, 2),
> +	MHI_CHANNEL_CONFIG_HW_UL(100, "IP_HW0", 128, 1),
> +	MHI_CHANNEL_CONFIG_HW_DL(101, "IP_HW0", 128, 2),
>  };
> 
>  static const struct mhi_event_config modem_qcom_v1_mhi_events[] = {
Thanks,
Bhaumik
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