[alsa-devel] [RFC PATCH 27/40] soundwire: Add Intel resource management algorithm

[Sanyog Kale]

On Thu, Jul 25, 2019 at 06:40:19PM -0500, Pierre-Louis Bossart wrote:
> This algorithm computes bus parameters like clock frequency, frame
> shape and port transport parameters based on active stream(s) running
> on the bus.
> 
> This implementation is optimal for Intel platforms. Developers can
> also implement their own .compute_params() callback for specific
> resource management algorithm.
> 
> Credits: this patch is based on an earlier internal contribution by
> Vinod Koul, Sanyog Kale, Shreyas Nc and Hardik Shah. All hard-coded
> values were removed from the initial contribution to use BIOS
> information instead.
> 
> FIXME: remove checkpatch report
> WARNING: Reusing the krealloc arg is almost always a bug
> +			group->rates = krealloc(group->rates,
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> ---
>  drivers/soundwire/Makefile                  |   2 +-
>  drivers/soundwire/algo_dynamic_allocation.c | 403 ++++++++++++++++++++
>  drivers/soundwire/bus.c                     |   3 +
>  drivers/soundwire/bus.h                     |  46 ++-
>  drivers/soundwire/stream.c                  |  20 +
>  include/linux/soundwire/sdw.h               |   5 +
>  6 files changed, 476 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/soundwire/algo_dynamic_allocation.c
> 
> diff --git a/drivers/soundwire/Makefile b/drivers/soundwire/Makefile
> index 88990cac48a7..f59a9d4a28fd 100644
> --- a/drivers/soundwire/Makefile
> +++ b/drivers/soundwire/Makefile
> @@ -5,7 +5,7 @@
>  
>  #Bus Objs
>  soundwire-bus-objs := bus_type.o bus.o slave.o mipi_disco.o stream.o \
> -			debugfs.o
> +			debugfs.o algo_dynamic_allocation.o
>  
>  obj-$(CONFIG_SOUNDWIRE_BUS) += soundwire-bus.o
>  
> diff --git a/drivers/soundwire/algo_dynamic_allocation.c b/drivers/soundwire/algo_dynamic_allocation.c
> new file mode 100644
> index 000000000000..89edb39162b8
> --- /dev/null
> +++ b/drivers/soundwire/algo_dynamic_allocation.c
> @@ -0,0 +1,403 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +// Copyright(c) 2015-18 Intel Corporation.
> +
> +/*
> + * Bandwidth management algorithm based on 2^n gears
> + *
> + */
> +
> +#include <linux/device.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/slab.h>
> +#include <linux/soundwire/sdw.h>
> +#include "bus.h"
> +
> +#define SDW_STRM_RATE_GROUPING		1
> +
> +struct sdw_group_params {
> +	unsigned int rate;
> +	int full_bw;
> +	int payload_bw;
> +	int hwidth;
> +};
> +
> +struct sdw_group {
> +	unsigned int count;
> +	unsigned int max_size;
> +	unsigned int *rates;
> +};
> +
> +struct sdw_transport_data {
> +	int hstart;
> +	int hstop;
> +	int block_offset;
> +	int sub_block_offset;
> +};
> +
> +
> +/**
> + * sdw_compute_port_params: Compute transport and port parameters
> + *
> + * @bus: SDW Bus instance
> + */
> +static int sdw_compute_port_params(struct sdw_bus *bus)
> +{
> +	struct sdw_group_params *params = NULL;
> +	struct sdw_group group;
> +	int ret;
> +
> +	ret = sdw_get_group_count(bus, &group);
> +	if (ret < 0)
> +		goto out;
> +
> +	if (group.count == 0)
> +		goto out;
> +
> +	params = kcalloc(group.count, sizeof(*params), GFP_KERNEL);
> +	if (!params) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
> +	/* Compute transport parameters for grouped streams */
> +	ret = sdw_compute_group_params(bus, params,
> +				       &group.rates[0], group.count);
> +	if (ret < 0)
> +		goto out;
> +
> +	_sdw_compute_port_params(bus, params, group.count);
> +
> +out:
> +	kfree(params);
> +	kfree(group.rates);
> +
> +	return ret;
> +}
> +
> +static int sdw_select_row_col(struct sdw_bus *bus, int clk_freq)
> +{
> +	struct sdw_master_prop *prop = &bus->prop;
> +	int frame_int, frame_freq;
> +	int r, c;
> +
> +	for (c = 0; c < SDW_FRAME_COLS; c++) {
> +		for (r = 0; r < SDW_FRAME_ROWS; r++) {
> +			if (sdw_rows[r] != prop->default_row ||
> +			    sdw_cols[c] != prop->default_col)
> +				continue;

Are we only supporting default rows and cols?

> +
> +			frame_int = sdw_rows[r] * sdw_cols[c];
> +			frame_freq = clk_freq / frame_int;
> +
> +			if ((clk_freq - (frame_freq * SDW_FRAME_CTRL_BITS)) <
> +			    bus->params.bandwidth)
> +				continue;
> +
> +			bus->params.row = sdw_rows[r];
> +			bus->params.col = sdw_cols[c];
> +			return 0;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> -- 
> 2.20.1
> 

--