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

Guennadi Liakhovetski
2019-07-26T15:43:32Z

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@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;
> +};
> +
> +static void sdw_compute_slave_ports(struct sdw_master_runtime *m_rt,
> + struct sdw_transport_data *t_data)
> +{
> + struct sdw_slave_runtime *s_rt = NULL;

Superfluous initialisation.

> + struct sdw_port_runtime *p_rt;
> + int port_bo, sample_int;
> + unsigned int rate, bps, ch = 0;

ditto for ch

> +
> + port_bo = t_data->block_offset;
> +
> + list_for_each_entry(s_rt, &m_rt->slave_rt_list, m_rt_node) {
> + rate = m_rt->stream->params.rate;
> + bps = m_rt->stream->params.bps;
> + sample_int = (m_rt->bus->params.curr_dr_freq / rate);
> +
> + list_for_each_entry(p_rt, &s_rt->port_list, port_node) {
> + ch = sdw_ch_mask_to_ch(p_rt->ch_mask);
> +
> + sdw_fill_xport_params(&p_rt->transport_params,
> + p_rt->num, true,
> + SDW_BLK_GRP_CNT_1,
> + sample_int, port_bo, port_bo >> 8,
> + t_data->hstart,
> + t_data->hstop,

I think the above two lines could fit in one

> + (SDW_BLK_GRP_CNT_1 * ch), 0x0);

superfluous parentheses

> +
> + sdw_fill_port_params(&p_rt->port_params,
> + p_rt->num, bps,
> + SDW_PORT_FLOW_MODE_ISOCH,
> + SDW_PORT_DATA_MODE_NORMAL);
> +
> + port_bo += bps * ch;
> + }
> + }
> +}
> +
> +static void sdw_compute_master_ports(struct sdw_master_runtime *m_rt,
> + struct sdw_group_params *params,
> + int port_bo, int hstop)
> +{
> + struct sdw_transport_data t_data = {0};
> + struct sdw_port_runtime *p_rt;
> + struct sdw_bus *bus = m_rt->bus;
> + int sample_int, hstart = 0;

superfluous initialisation

> + unsigned int rate, bps, ch, no_ch;
> +
> + rate = m_rt->stream->params.rate;
> + bps = m_rt->stream->params.bps;
> + ch = m_rt->ch_count;
> + sample_int = (bus->params.curr_dr_freq / rate);

superfluous parentheses

> +
> + if (rate != params->rate)
> + return;
> +
> + t_data.hstop = hstop;
> + hstart = hstop - params->hwidth + 1;
> + t_data.hstart = hstart;
> +
> + list_for_each_entry(p_rt, &m_rt->port_list, port_node) {
> + no_ch = sdw_ch_mask_to_ch(p_rt->ch_mask);
> +
> + sdw_fill_xport_params(&p_rt->transport_params, p_rt->num,
> + true, SDW_BLK_GRP_CNT_1, sample_int,
> + port_bo, port_bo >> 8, hstart, hstop,
> + (SDW_BLK_GRP_CNT_1 * no_ch), 0x0);

superfluous parentheses

> +
> + sdw_fill_port_params(&p_rt->port_params,
> + p_rt->num, bps,
> + SDW_PORT_FLOW_MODE_ISOCH,
> + SDW_PORT_DATA_MODE_NORMAL);
> +
> + /* Check for first entry */
> + if (!(p_rt == list_first_entry(&m_rt->port_list,
> + struct sdw_port_runtime,
> + port_node))) {

you wanted to write "if (p_rt != ...)"

> + port_bo += bps * ch;
> + continue;
> + }
> +
> + t_data.hstart = hstart;
> + t_data.hstop = hstop;

You already set these two above

> + t_data.block_offset = port_bo;
> + t_data.sub_block_offset = 0;
> + port_bo += bps * ch;
> + }
> +
> + sdw_compute_slave_ports(m_rt, &t_data);
> +}
> +
> +static void _sdw_compute_port_params(struct sdw_bus *bus,
> + struct sdw_group_params *params, int count)
> +{
> + struct sdw_master_runtime *m_rt = NULL;

superfluous initialisation

> + int hstop = bus->params.col - 1;
> + int block_offset, port_bo, i;
> +
> + /* Run loop for all groups to compute transport parameters */
> + for (i = 0; i < count; i++) {
> + port_bo = 1;
> + block_offset = 1;
> +
> + list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
> + sdw_compute_master_ports(m_rt, &params[i],
> + port_bo, hstop);
> +
> + block_offset += m_rt->ch_count *
> + m_rt->stream->params.bps;
> + port_bo = block_offset;
> + }
> +
> + hstop = hstop - params[i].hwidth;

hstop -= ...

> + }
> +}
> +
> +static int sdw_compute_group_params(struct sdw_bus *bus,
> + struct sdw_group_params *params,
> + int *rates, int count)
> +{
> + struct sdw_master_runtime *m_rt = NULL;

ditto

> + int sel_col = bus->params.col;
> + unsigned int rate, bps, ch;
> + int i, column_needed = 0;
> +
> + /* Calculate bandwidth per group */
> + for (i = 0; i < count; i++) {
> + params[i].rate = rates[i];
> + params[i].full_bw = bus->params.curr_dr_freq / params[i].rate;
> + }
> +
> + list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
> + rate = m_rt->stream->params.rate;
> + bps = m_rt->stream->params.bps;
> + ch = m_rt->ch_count;
> +
> + for (i = 0; i < count; i++) {
> + if (rate == params[i].rate)
> + params[i].payload_bw += bps * ch;

I don't know about the algorithm, rates can repeat, right? So you cannot break
out of the loop here once you found one match?

> + }
> + }
> +
> + for (i = 0; i < count; i++) {
> + params[i].hwidth = (sel_col *
> + params[i].payload_bw + params[i].full_bw - 1) /
> + params[i].full_bw;
> +
> + column_needed += params[i].hwidth;
> + }
> +
> + if (column_needed > sel_col - 1)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int sdw_add_element_group_count(struct sdw_group *group,
> + unsigned int rate)
> +{
> + int num = group->count;
> + int i;
> +
> + for (i = 0; i <= num; i++) {
> + if (rate == group->rates[i])

Are you sure this is correct? You actually check count + 1 rates - from 0
to count inclusively. I think this isn't what you wanted to do, so my
proposal below only checks count rates.

> + break;
> +
> + if (i != num)
> + continue;
> +
> + if (group->count >= group->max_size) {
> + group->max_size += 1;
> + group->rates = krealloc(group->rates,
> + (sizeof(int) * group->max_size),
> + GFP_KERNEL);
> + if (!group->rates)
> + return -ENOMEM;
> + }
> +
> + group->rates[group->count++] = rate;
> + }

How about this:

for (i = 0; i < num; i++)
if (rate == group->rates[i])
return 0;

if (group->count >= group->max_size) {
group->max_size += 1;
group->rates = krealloc(group->rates,
(sizeof(int) * group->max_size),
GFP_KERNEL);
if (!group->rates)
return -ENOMEM;
}

group->rates[group->count++] = rate;

return 0;

> +
> + return 0;
> +}
> +
> +static int sdw_get_group_count(struct sdw_bus *bus,
> + struct sdw_group *group)
> +{
> + struct sdw_master_runtime *m_rt;
> + unsigned int rate;
> + int ret = 0;
> +
> + group->count = 0;
> + group->max_size = SDW_STRM_RATE_GROUPING;
> + group->rates = kcalloc(group->max_size, sizeof(int), GFP_KERNEL);
> + if (!group->rates)
> + return -ENOMEM;
> +
> + list_for_each_entry(m_rt, &bus->m_rt_list, bus_node) {
> + rate = m_rt->stream->params.rate;
> + if (m_rt == list_first_entry(&bus->m_rt_list,
> + struct sdw_master_runtime,
> + bus_node)) {
> + group->rates[group->count++] = rate;
> +
> + } else {
> + ret = sdw_add_element_group_count(group, rate);
> + if (ret < 0)

Actually it looks like you should free rates here? I see that not doing this
makes the caller function below easier, but I'd say this is more error-
prone... Up to you but I'd go the "safe" way - if it fails, it frees itself,
if it succeeds - it's freed elsewhere.

> + return ret;
> + }
> + }
> +
> + return ret;

I think this will always return 0 here, so you don't need the "ret"
variable in the function scope, you only need it in the "else"
scope above.

> +}
> +
> +/**
> + * 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);

Depending whether or not you change the code above, this might change
too.

> +
> + 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;
> +
> + 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;
> +}
> +
> +/**
> + * sdw_compute_bus_params: Compute bus parameters
> + *
> + * @bus: SDW Bus instance
> + */
> +static int sdw_compute_bus_params(struct sdw_bus *bus)
> +{
> + unsigned int max_dr_freq, curr_dr_freq = 0;
> + struct sdw_master_prop *mstr_prop = NULL;

superfluous initialisation

> + int i, clk_values, ret;
> + bool is_gear = false;
> + u32 *clk_buf;
> +
> + mstr_prop = &bus->prop;
> + if (!mstr_prop)

this is impossible, it's an address of bus->prop...

> + return -EINVAL;
> +
> + if (mstr_prop->num_clk_gears) {
> + clk_values = mstr_prop->num_clk_gears;
> + clk_buf = mstr_prop->clk_gears;
> + is_gear = true;
> + } else if (mstr_prop->num_clk_freq) {
> + clk_values = mstr_prop->num_clk_freq;
> + clk_buf = mstr_prop->clk_freq;
> + } else {
> + clk_values = 1;
> + clk_buf = NULL;
> + }
> +
> + max_dr_freq = mstr_prop->max_clk_freq * SDW_DOUBLE_RATE_FACTOR;
> +
> + for (i = 0; i < clk_values; i++) {
> + if (!clk_buf)
> + curr_dr_freq = max_dr_freq;
> + else
> + curr_dr_freq = (is_gear) ?

superfluous parentheses

> + (max_dr_freq >> clk_buf[i]) :

ditto

> + clk_buf[i] * SDW_DOUBLE_RATE_FACTOR;
> +
> + if (curr_dr_freq <= bus->params.bandwidth)
> + continue;
> +
> + break;

I think this is raw code, you'd actually want to write this as

if (curr_dr_freq > bus->params.bandwidth)
break;

> +
> + /*
> + * TODO: Check all the Slave(s) port(s) audio modes and find
> + * whether given clock rate is supported with glitchless
> + * transition.
> + */
> + }
> +
> + if (i == clk_values)
> + return -EINVAL;
> +
> + ret = sdw_select_row_col(bus, curr_dr_freq);
> + if (ret < 0)
> + return -EINVAL;
> +
> + bus->params.curr_dr_freq = curr_dr_freq;
> + return 0;
> +}
> +
> +/**
> + * sdw_compute_params: Compute bus, transport and port parameters
> + *
> + * @bus: SDW Bus instance
> + */
> +int sdw_compute_params(struct sdw_bus *bus)
> +{
> + int ret;
> +
> + /* Computes clock frequency, frame shape and frame frequency */
> + ret = sdw_compute_bus_params(bus);
> + if (ret < 0) {
> + dev_err(bus->dev, "Compute bus params failed: %d", ret);
> + return ret;
> + }
> +
> + /* Compute transport and port params */
> + ret = sdw_compute_port_params(bus);
> + if (ret < 0) {
> + dev_err(bus->dev, "Compute transport params failed: %d", ret);
> + return ret;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(sdw_compute_params);
> diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
> index 2354675ef104..76a180578712 100644
> --- a/drivers/soundwire/bus.c
> +++ b/drivers/soundwire/bus.c
> @@ -51,6 +51,9 @@ int sdw_add_bus_master(struct sdw_bus *bus)
>
> bus->debugfs = sdw_bus_debugfs_init(bus);
>
> + if (!bus->compute_params)
> + bus->compute_params = &sdw_compute_params;

I think it is more usual to not use "&" with functions, but it's valid too

> +
> /*
> * Device numbers in SoundWire are 0 through 15. Enumeration device
> * number (0), Broadcast device number (15), Group numbers (12 and
> diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
> index c57c9c23f6ca..fdb7ce034fdf 100644
> --- a/drivers/soundwire/bus.h
> +++ b/drivers/soundwire/bus.h
> @@ -72,6 +72,7 @@ struct sdw_msg {
> };
>
> #define SDW_DOUBLE_RATE_FACTOR 2
> +#define SDW_STRM_RATE_GROUPING 1
>
> extern int sdw_rows[SDW_FRAME_ROWS];
> extern int sdw_cols[SDW_FRAME_COLS];
> @@ -157,9 +158,50 @@ int sdw_transfer_defer(struct sdw_bus *bus, struct sdw_msg *msg,
> int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
> u32 addr, size_t count, u16 dev_num, u8 flags, u8 *buf);
>
> +/* Retrieve and return channel count from channel mask */
> +static inline int sdw_ch_mask_to_ch(int ch_mask)
> +{
> + int c = 0;

superfluous initialisation

> +
> + for (c = 0; ch_mask; ch_mask >>= 1)
> + c += ch_mask & 1;

isn't there a built-in or something to count set bits... You could use ffs() to
at least not loop 31 times for 0x80000000

> +
> + return c;
> +}
> +
> +/* Fill transport parameter data structure */
> +static inline void sdw_fill_xport_params(struct sdw_transport_params *params,
> + int port_num, bool grp_ctrl_valid,
> + int grp_ctrl, int sample_int,
> + int off1, int off2,
> + int hstart, int hstop,
> + int pack_mode, int lane_ctrl)
> +{
> + params->port_num = port_num;
> + params->blk_grp_ctrl_valid = grp_ctrl_valid;
> + params->blk_grp_ctrl = grp_ctrl;
> + params->sample_interval = sample_int;
> + params->offset1 = off1;
> + params->offset2 = off2;
> + params->hstart = hstart;
> + params->hstop = hstop;
> + params->blk_pkg_mode = pack_mode;
> + params->lane_ctrl = lane_ctrl;
> +}
> +
> +/* Fill port parameter data structure */
> +static inline void sdw_fill_port_params(struct sdw_port_params *params,
> + int port_num, int bps,
> + int flow_mode, int data_mode)
> +{
> + params->num = port_num;
> + params->bps = bps;
> + params->flow_mode = flow_mode;
> + params->data_mode = data_mode;
> +}
> +
> /* Read-Modify-Write Slave register */
> -static inline int
> -sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
> +static inline int sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
> {
> int tmp;
>
> diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
> index 75b9ad1fb1a6..add7c121d084 100644
> --- a/drivers/soundwire/stream.c
> +++ b/drivers/soundwire/stream.c
> @@ -1485,6 +1485,16 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
> bus->params.bandwidth += m_rt->stream->params.rate *
> m_rt->ch_count * m_rt->stream->params.bps;
>
> + /* Compute params */
> + if (bus->compute_params) {
> + ret = bus->compute_params(bus);
> + if (ret < 0) {
> + dev_err(bus->dev,
> + "Compute params failed: %d", ret);
> + return ret;
> + }
> + }
> +
> /* Program params */
> ret = sdw_program_params(bus);
> if (ret < 0) {
> @@ -1704,6 +1714,16 @@ static int _sdw_deprepare_stream(struct sdw_stream_runtime *stream)
> bus->params.bandwidth -= m_rt->stream->params.rate *
> m_rt->ch_count * m_rt->stream->params.bps;
>
> + /* Compute params */
> + if (bus->compute_params) {
> + ret = bus->compute_params(bus);
> + if (ret < 0) {
> + dev_err(bus->dev,
> + "Compute params failed: %d", ret);
> + return ret;
> + }
> + }
> +
> /* Program params */
> ret = sdw_program_params(bus);
> if (ret < 0) {
> diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
> index b6acc436ac80..c7dfc824be80 100644
> --- a/include/linux/soundwire/sdw.h
> +++ b/include/linux/soundwire/sdw.h
> @@ -730,6 +730,7 @@ struct sdw_master_ops {
> * Bit set implies used number, bit clear implies unused number.
> * @bus_lock: bus lock
> * @msg_lock: message lock
> + * @compute_params: points to Bus resource management implementation
> * @ops: Master callback ops
> * @port_ops: Master port callback ops
> * @params: Current bus parameters
> @@ -752,6 +753,7 @@ struct sdw_bus {
> DECLARE_BITMAP(assigned, SDW_MAX_DEVICES);
> struct mutex bus_lock;
> struct mutex msg_lock;
> + int (*compute_params)(struct sdw_bus *bus);
> const struct sdw_master_ops *ops;
> const struct sdw_master_port_ops *port_ops;
> struct sdw_bus_params params;
> @@ -852,6 +854,9 @@ struct sdw_stream_runtime {
>
> struct sdw_stream_runtime *sdw_alloc_stream(char *stream_name);
> void sdw_release_stream(struct sdw_stream_runtime *stream);
> +
> +int sdw_compute_params(struct sdw_bus *bus);
> +
> int sdw_stream_add_master(struct sdw_bus *bus,
> struct sdw_stream_config *stream_config,
> struct sdw_port_config *port_config,
> --
> 2.20.1
>
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