[alsa-devel] [PATCH v7 09/10] soundwire: Add support for multi link bank switch

[Pierre-Louis Bossart]

The series looks pretty good now, I just found one possible improvement 
below
Thanks!

>   
> -static int sdw_bank_switch(struct sdw_bus *bus)
> +static int sdw_bank_switch(struct sdw_bus *bus, int m_rt_count)
>   {
>   	int col_index, row_index;
> +	bool multi_link;
>   	struct sdw_msg *wr_msg;
>   	u8 *wbuf = NULL;
>   	int ret = 0;
> @@ -638,6 +639,8 @@ static int sdw_bank_switch(struct sdw_bus *bus)
>   	if (!wr_msg)
>   		return -ENOMEM;
>   
> +	bus->defer_msg.msg = wr_msg;
> +
>   	wbuf = kzalloc(sizeof(*wbuf), GFP_KERNEL);
>   	if (!wbuf) {
>   		ret = -ENOMEM;
> @@ -658,17 +661,29 @@ static int sdw_bank_switch(struct sdw_bus *bus)
>   					SDW_MSG_FLAG_WRITE, wbuf);
>   	wr_msg->ssp_sync = true;
>   
> -	ret = sdw_transfer(bus, wr_msg);
> +	/*
> +	 * Set the multi_link flag only when both the hardware supports
> +	 * and there is a stream handled by multiple masters
> +	 */
> +	multi_link = bus->multi_link && (m_rt_count > 1);
> +
> +	if (multi_link)
> +		ret = sdw_transfer_defer(bus, wr_msg, &bus->defer_msg);
> +	else
> +		ret = sdw_transfer(bus, wr_msg);
> +
>   	if (ret < 0) {
>   		dev_err(bus->dev, "Slave frame_ctrl reg write failed");
>   		goto error;
>   	}
>   
> -	kfree(wr_msg);
> -	kfree(wbuf);
> -	bus->defer_msg.msg = NULL;
> -	bus->params.curr_bank = !bus->params.curr_bank;
> -	bus->params.next_bank = !bus->params.next_bank;
> +	if (!bus->multi_link) {
> +		kfree(wr_msg);
> +		kfree(wbuf);
> +		bus->defer_msg.msg = NULL;
> +		bus->params.curr_bank = !bus->params.curr_bank;
> +		bus->params.next_bank = !bus->params.next_bank;
> +	}

Should this test be extended to the case where the bus can support 
multi-link but m_rt_count ==1
should it be
if (!multi_link)
?