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

Pierre-Louis Bossart
2019-07-26T17:55:29Z

Thanks Guennadi for looking at this code, it's hard to review and figure
things out...
I replied to each, even trivial ones, to have a trace of all the issues.

>> +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.

ok

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

ok

>> +
>> + 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

likely yes.

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

yep

>> +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

yes

>
>> + 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

yes

>> +
>> + 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

yes

>
>> +
>> + 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 != ...)"

bad code indeed, thanks for spotting this. I need to double-check this
one, now I don't trust the ==
it could also be that it was meant to be a NULL check on the first entry.

>
>> + port_bo += bps * ch;
>> + continue;
>> + }
>> +
>> + t_data.hstart = hstart;
>> + t_data.hstop = hstop;
>
> You already set these two above

need to check this as well.

>
>> + 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

yes

>
>> + 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 -= ...

yes

>
>> + }
>> +}
>> +
>> +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

yes

>> + 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?

This code looks wrong. Need to get an intravenous caffeine injection.

>
>> + }
>> + }
>> +
>> + 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.

I'll have to double check. There's already the warning on krealloc that
looks suspicious as well.

>
>> + 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;

will check offline and see.

>> +
>> + 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.

good catch, will look into this.

>
>> + 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.

will check. In general I avoid per-scope declarations.

>> +}
>> +
>> +/**
>> + * 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.

will check

>> +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

yes

>> + 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...

Gah, yes.

>> + 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

yes and yes
>
>> + 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;

I saw this before my Summer break and forgot about it. yes it needs to
be fixed.

>>
>> 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

yes, will fix

>> +/* Retrieve and return channel count from channel mask */
>> +static inline int sdw_ch_mask_to_ch(int ch_mask)
>> +{
>> + int c = 0;
>
> superfluous initialisation

yes

>
>> +
>> + 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

will check