Re: [alsa-devel] [RFC PATCH 21/40] soundwire: export helpers to find row and column values

Pierre-Louis Bossart
2019-08-05T15:30:40Z

On 8/5/19 4:39 AM, Sanyog Kale wrote:
> On Thu, Jul 25, 2019 at 06:40:13PM -0500, Pierre-Louis Bossart wrote:
>> Add a prefix for common tables and export 2 helpers to set the frame
>> shapes based on row/col values.
>>
>> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
>> ---
>> drivers/soundwire/bus.h | 7 +++++--
>> drivers/soundwire/stream.c | 14 ++++++++------
>> 2 files changed, 13 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
>> index 06ac4adb0074..c57c9c23f6ca 100644
>> --- a/drivers/soundwire/bus.h
>> +++ b/drivers/soundwire/bus.h
>> @@ -73,8 +73,11 @@ struct sdw_msg {
>>
>> #define SDW_DOUBLE_RATE_FACTOR 2
>>
>> -extern int rows[SDW_FRAME_ROWS];
>> -extern int cols[SDW_FRAME_COLS];
>> +extern int sdw_rows[SDW_FRAME_ROWS];
>> +extern int sdw_cols[SDW_FRAME_COLS];
>> +
>> +int sdw_find_row_index(int row);
>> +int sdw_find_col_index(int col);
>
> We use index values only in bank switch operations to program registers. Do we
> really need to export sdw_find_row_index & sdw_find_col_index?? If i understand
> correctly the allocation algorithm only needs to know about cols and rows values
> and not index.

The allocation does work with cols and rows indeed, but will first run
the code below where the information f is required:

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;
}

as for the two helpers, they are used in both the allocation and the
cadence code (to determine the initial frame shape from properties).

And other solutions for non-Intel platforms will also need this to
convert from indices to frame shape.

So yes all of this is needed.

>
>>
>> /**
>> * sdw_port_runtime: Runtime port parameters for Master or Slave
>> diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
>> index a0476755a459..53f5e790fcd7 100644
>> --- a/drivers/soundwire/stream.c
>> +++ b/drivers/soundwire/stream.c
>> @@ -21,37 +21,39 @@
>> * The rows are arranged as per the array index value programmed
>> * in register. The index 15 has dummy value 0 in order to fill hole.
>> */
>> -int rows[SDW_FRAME_ROWS] = {48, 50, 60, 64, 75, 80, 125, 147,
>> +int sdw_rows[SDW_FRAME_ROWS] = {48, 50, 60, 64, 75, 80, 125, 147,
>> 96, 100, 120, 128, 150, 160, 250, 0,
>> 192, 200, 240, 256, 72, 144, 90, 180};
>>
>> -int cols[SDW_FRAME_COLS] = {2, 4, 6, 8, 10, 12, 14, 16};
>> +int sdw_cols[SDW_FRAME_COLS] = {2, 4, 6, 8, 10, 12, 14, 16};
>>
>> -static int sdw_find_col_index(int col)
>> +int sdw_find_col_index(int col)
>> {
>> int i;
>>
>> for (i = 0; i < SDW_FRAME_COLS; i++) {
>> - if (cols[i] == col)
>> + if (sdw_cols[i] == col)
>> return i;
>> }
>>
>> pr_warn("Requested column not found, selecting lowest column no: 2\n");
>> return 0;
>> }
>> +EXPORT_SYMBOL(sdw_find_col_index);
>>
>> -static int sdw_find_row_index(int row)
>> +int sdw_find_row_index(int row)
>> {
>> int i;
>>
>> for (i = 0; i < SDW_FRAME_ROWS; i++) {
>> - if (rows[i] == row)
>> + if (sdw_rows[i] == row)
>> return i;
>> }
>>
>> pr_warn("Requested row not found, selecting lowest row no: 48\n");
>> return 0;
>> }
>> +EXPORT_SYMBOL(sdw_find_row_index);
>>
>> static int _sdw_program_slave_port_params(struct sdw_bus *bus,
>> struct sdw_slave *slave,
>> --
>> 2.20.1
>>
>