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

[Pierre-Louis Bossart]

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@xxxxxxxxxxxxxxx>
> > ---
> >   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