Re: [PATCH v4 2/2] soundwire: amd: refactor bandwidth calculation logic

[Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>]

On 1/29/26 07:14, Vijendar Mukunda wrote:
> For current platforms(ACP6.3/ACP7.0/ACP7.1/ACP7.2), AMD SoundWire manager
> doesn't have banked registers for data port programming on Manager's side.
> Need to use fixed block offsets, hstart & hstop for manager ports.
> Earlier amd manager driver has support for 12MHz as a bus clock frequency
> with frame size as 50 x 10 with fixed block offset mapping based on port
> number. Got a requirement to support 6MHz bus clock frequency with
> different frame shapes 50 x 10 and 125 x 2.

the two frame shapes don't carry the same number of bits (500 v. 250). There's probably an additional variable at play, maybe frame rate? Or is 50x10 for 12 MHz and 125x2 for 6 MHz?

> For current platforms, amd manager driver supports only two bus clock
> frequencies(12MHz & 6MHz). Refactor bandwidth logic to support different
> bus clock frequencies.
> 
> Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@amd.com>
> ---
>  drivers/soundwire/amd_manager.c   | 57 ++++++++++++++++++++++++++++---
>  include/linux/soundwire/sdw_amd.h |  4 +++
>  2 files changed, 57 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/soundwire/amd_manager.c b/drivers/soundwire/amd_manager.c
> index b53f781e4e74..7cd95a907f67 100644
> --- a/drivers/soundwire/amd_manager.c
> +++ b/drivers/soundwire/amd_manager.c
> @@ -476,12 +476,16 @@ static u32 amd_sdw_read_ping_status(struct sdw_bus *bus)
>  
>  static int amd_sdw_compute_params(struct sdw_bus *bus, struct sdw_stream_runtime *stream)
>  {
> +	struct amd_sdw_manager *amd_manager = to_amd_sdw(bus);
>  	struct sdw_transport_data t_data = {0};
>  	struct sdw_master_runtime *m_rt;
>  	struct sdw_port_runtime *p_rt;
>  	struct sdw_bus_params *b_params = &bus->params;
>  	int port_bo, hstart, hstop, sample_int;
> -	unsigned int rate, bps;
> +	unsigned int rate, bps, channels;
> +	int stream_slot_size, max_slots;
> +	static int next_offset[AMD_SDW_MAX_MANAGER_COUNT] = {1};
> +	unsigned int inst_id = amd_manager->instance;
>  
>  	port_bo = 0;
>  	hstart = 1;
> @@ -492,11 +496,51 @@ static int amd_sdw_compute_params(struct sdw_bus *bus, struct sdw_stream_runtime
>  	list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
>  		rate = m_rt->stream->params.rate;
>  		bps = m_rt->stream->params.bps;
> +		channels = m_rt->stream->params.ch_count;
>  		sample_int = (bus->params.curr_dr_freq / rate);
> +
> +		/* Compute slots required for this stream dynamically */
> +		stream_slot_size = bps * channels;
> +
>  		list_for_each_entry(p_rt, &m_rt->port_list, port_node) {
> -			port_bo = (p_rt->num * 64) + 1;
> -			dev_dbg(bus->dev, "p_rt->num=%d hstart=%d hstop=%d port_bo=%d\n",
> -				p_rt->num, hstart, hstop, port_bo);
> +			if (p_rt->num >= amd_manager->max_ports) {
> +				dev_err(bus->dev, "Port %d exceeds max ports %d\n",
> +					p_rt->num, amd_manager->max_ports);
> +				return -EINVAL;
> +			}
> +
> +			if (!amd_manager->port_offset_map[p_rt->num]) {
> +				/*
> +				 * port block offset calculation for 6MHz bus clock frequency with
> +				 * different frame sizes 50 x 10 and 125 x 2
> +				 */
> +				if (bus->params.curr_dr_freq == 12000000) {
> +					max_slots = bus->params.row * (bus->params.col - 1);
> +					if (next_offset[inst_id] + stream_slot_size <=
> +					    (max_slots - 1)) {
> +						amd_manager->port_offset_map[p_rt->num] =
> +									next_offset[inst_id];
> +						next_offset[inst_id] += stream_slot_size;
> +					} else {
> +						dev_err(bus->dev,
> +							"No space for port %d\n", p_rt->num);
> +						return -ENOMEM;
> +					}
> +				} else {
> +					 /*
> +					  * port block offset calculation for 12MHz bus clock
> +					  * frequency
> +					  */
> +					amd_manager->port_offset_map[p_rt->num] =
> +									(p_rt->num * 64) + 1;
> +				}
> +			}
> +			port_bo = amd_manager->port_offset_map[p_rt->num];
> +			dev_dbg(bus->dev,
> +				"Port=%d hstart=%d hstop=%d port_bo=%d slots=%d max_ports=%d\n",
> +				p_rt->num, hstart, hstop, port_bo, stream_slot_size,
> +				amd_manager->max_ports);
> +
>  			sdw_fill_xport_params(&p_rt->transport_params, p_rt->num,
>  					      false, SDW_BLK_GRP_CNT_1, sample_int,
>  					      port_bo, port_bo >> 8, hstart, hstop,
> @@ -1089,6 +1133,11 @@ static int amd_sdw_manager_probe(struct platform_device *pdev)
>  	default:
>  		return -EINVAL;
>  	}
> +	amd_manager->max_ports = amd_manager->num_dout_ports + amd_manager->num_din_ports;
> +	amd_manager->port_offset_map = devm_kcalloc(dev, amd_manager->max_ports,
> +						    sizeof(int), GFP_KERNEL);
> +	if (!amd_manager->port_offset_map)
> +		return -ENOMEM;
>  
>  	prop = &amd_manager->bus.prop;
>  	prop->mclk_freq = AMD_SDW_BUS_BASE_FREQ;
> diff --git a/include/linux/soundwire/sdw_amd.h b/include/linux/soundwire/sdw_amd.h
> index fe31773d5210..470360a2723c 100644
> --- a/include/linux/soundwire/sdw_amd.h
> +++ b/include/linux/soundwire/sdw_amd.h
> @@ -66,8 +66,10 @@ struct sdw_amd_dai_runtime {
>   * @status: peripheral devices status array
>   * @num_din_ports: number of input ports
>   * @num_dout_ports: number of output ports
> + * @max_ports: total number of input ports and output ports
>   * @cols_index: Column index in frame shape
>   * @rows_index: Rows index in frame shape
> + * @port_offset_map: dynamic array to map port block offset
>   * @instance: SoundWire manager instance
>   * @quirks: SoundWire manager quirks
>   * @wake_en_mask: wake enable mask per SoundWire manager
> @@ -92,10 +94,12 @@ struct amd_sdw_manager {
>  
>  	int num_din_ports;
>  	int num_dout_ports;
> +	int max_ports;
>  
>  	int cols_index;
>  	int rows_index;
>  
> +	int *port_offset_map;
>  	u32 instance;
>  	u32 quirks;
>  	u32 wake_en_mask;