On Wed, Mar 15, 2017 at 7:17 PM, Charles Keepax ckeepax@opensource.wolfsonmicro.com wrote:
On Wed, Mar 15, 2017 at 05:33:06PM +0200, Daniel Baluta wrote:
WM8960 derives bit clock from sysclock using BCLKDIV[3:0] of R8 clocking register (See WM8960 datasheet, page 71).
There are use cases, like this: aplay -Dhw:0,0 -r 48000 -c 1 -f S20_3LE -t raw audio48k20b_3LE1c.pcm
where no BCLKDIV applied to sysclock can give us the exact requested bitclk, so driver fails to configure clocking and aplay fails to run.
Fix this by relaxing bitclk computation, so that when no exact value can be derived from sysclk pick the closest value greater than expected bitclk.
Suggested-by: Charles Keepax ckeepax@opensource.wolfsonmicro.com Signed-off-by: Daniel Baluta daniel.baluta@nxp.com
sound/soc/codecs/wm8960.c | 39 +++++++++++++++++++++++++++++++++------ 1 file changed, 33 insertions(+), 6 deletions(-)
diff --git a/sound/soc/codecs/wm8960.c b/sound/soc/codecs/wm8960.c index cb2ff2d..1669b45 100644 --- a/sound/soc/codecs/wm8960.c +++ b/sound/soc/codecs/wm8960.c @@ -611,6 +611,10 @@ static const int bclk_divs[] = {
- lrclk = sysclk / dac_divs- 10 * bclk = sysclk / bclk_divs
- If we cannot find an exact match for (sysclk, lrclk, bclk)
- triplet, we relax the bclk such that bclk is chosen as the
- closest available frequency greater than expected bclk.
- @wm8960_priv: wm8960 codec private data
- @mclk: MCLK used to derive sysclk
- @_i: sysclk_divs index for found sysclk
@@ -620,14 +624,14 @@ static const int bclk_divs[] = {
- Returns:
- -1, in case no sysclk frequency available found
- 0, in case an exact match is found. See @_i, @_j, @_k
*/
int wm8960_configure_sysclk(struct wm8960_priv *wm8960, int mclk, int *_i, int *_j, int *_k) { int sysclk, bclk, lrclk; int i, j, k;
int diff;
int diff, closest = mclk;Don't you need to initialise diff here too?
It shouldn't be necessary. Diff is always initialized before used. I added diff variable to avoid always writing: sysclk - bclk * bclk_divs[k] / 10;
bclk = wm8960->bclk; lrclk = wm8960->lrclk;@@ -648,6 +652,12 @@ int wm8960_configure_sysclk(struct wm8960_priv *wm8960, int mclk, *_k = k; break; }
if (diff > 0 && closest > diff) {*_i = i;*_j = j;*_k = k;closest = diff;} } if (k != ARRAY_SIZE(bclk_divs)) break;@@ -656,10 +666,16 @@ int wm8960_configure_sysclk(struct wm8960_priv *wm8960, int mclk, break; }
/* exact match */ if (i != ARRAY_SIZE(sysclk_divs)) return 0;
return -1;
/* no match */if (closest == mclk)return -1;/* relaxed match */return 1;Do we need to differenciate between relaxed and an actual match?
In my implementation yes. Because if an actual match happens we go directly to "configure_clock" label. If a relaxed match happens we keep this in mind for later and for now we try to see if a PLL out freq is available.
Finally, if no PLL out freq is available we go and use the "relaxed" match.
}
static int wm8960_configure_clocking(struct snd_soc_codec *codec) @@ -668,6 +684,7 @@ static int wm8960_configure_clocking(struct snd_soc_codec *codec) int sysclk, bclk, lrclk, freq_out, freq_in; u16 iface1 = snd_soc_read(codec, WM8960_IFACE1); int i, j, k;
int best_sysclk_div, best_dac_div, best_bclk_div = -1; int ret; if (!(iface1 & (1<<6))) {@@ -705,10 +722,14 @@ static int wm8960_configure_clocking(struct snd_soc_codec *codec) ret = wm8960_configure_sysclk(wm8960, freq_out, &i, &j, &k); if (ret == 0) goto configure_clock;
else if (wm8960->clk_id != WM8960_SYSCLK_AUTO) {
else if (ret < 0 && wm8960->clk_id != WM8960_SYSCLK_AUTO) { dev_err(codec->dev, "failed to configure clock\n"); return -EINVAL; }/* there is still hope, keep this if no PLL out available */best_sysclk_div = i;best_dac_div = j;best_bclk_div = k;Enabling the PLL just to avoid running the BCLK a little fast doesn't really seem worth it and it would make the code much more obvious.
That's a nice suggestion. With this we could remove the pll part. Not sure if there are any negative side effects.
I will do some tests.
thanks, Daniel.