[alsa-devel] [PATCH v2] ASoC: da7219: Use clk_round_rate to handle enabled bclk/wclk case

[Adam Thomson]

For some platforms where DA7219 is the DAI clock master, BCLK/WCLK
will be set and enabled prior to the codec's hw_params() function
being called. It is possible the platform requires a different
BCLK configuration than would be chosen by hw_params(), for
example S16_LE format needed with a 64-bit frame to satisfy certain
devices using the clocks.

To handle those kinds of scenarios, the use of clk_round_rate() is
now employed as part of hw_params(). If BCLK is already enabled
then this function will just return the currently set rate, if it
is valid for the desired frame size, so the subsequent call to
clk_set_rate() will succeed and nothing changes with regards to
clocking. In addition the specific BCLK & WCLK recalc_rate()
implementations needed updating to always give back a real value,
as those functions are called as part of the clk init code and a
real value is needed for the clk_round_rate() call to work as
expected.

Signed-off-by: Adam Thomson <Adam.Thomson.Opensource at diasemi.com>
---
Changes in v2:
 - Removed clk_round_rate() call for WCLK/SR as this is not sensible.
 - Added checking after clk_round_rate() call for BCLK to verify returne rate is
   suitable for the hw_params() desired frame size.

 sound/soc/codecs/da7219.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
index 5f5fa34..206d01c 100644
--- a/sound/soc/codecs/da7219.c
+++ b/sound/soc/codecs/da7219.c
@@ -1621,6 +1621,21 @@ static int da7219_hw_params(struct snd_pcm_substream *substream,
 
 		if (bclk) {
 			bclk_rate = frame_size * sr;
+			/*
+			 * Rounding the rate here avoids failure trying to set a
+			 * new rate on an already enabled bclk. In that
+			 * instance this will just set the same rate as is
+			 * currently in use, and so should continue without
+			 * problem, as long as the BCLK rate is suitable for the
+			 * desired frame size.
+			 */
+			bclk_rate = clk_round_rate(bclk, bclk_rate);
+			if ((bclk_rate / sr) < frame_size) {
+				dev_err(component->dev,
+					"BCLK rate mismatch against frame size");
+				return -EINVAL;
+			}
+
 			ret = clk_set_rate(bclk, bclk_rate);
 			if (ret) {
 				dev_err(component->dev,
@@ -1927,9 +1942,6 @@ static unsigned long da7219_wclk_recalc_rate(struct clk_hw *hw,
 	struct snd_soc_component *component = da7219->component;
 	u8 fs = snd_soc_component_read32(component, DA7219_SR);
 
-	if (!da7219->master)
-		return 0;
-
 	switch (fs & DA7219_SR_MASK) {
 	case DA7219_SR_8000:
 		return 8000;
@@ -2016,9 +2028,6 @@ static unsigned long da7219_bclk_recalc_rate(struct clk_hw *hw,
 	u8 bclks_per_wclk = snd_soc_component_read32(component,
 						     DA7219_DAI_CLK_MODE);
 
-	if (!da7219->master)
-		return 0;
-
 	switch (bclks_per_wclk & DA7219_DAI_BCLKS_PER_WCLK_MASK) {
 	case DA7219_DAI_BCLKS_PER_WCLK_32:
 		return parent_rate * 32;
-- 
1.9.1