[PATCH] ASoC: soc-pcm: Preserve hw parameters from components in dpcm_runtime_setup_fe

[Peter Ujfalusi <peter.ujfalusi@linux.intel.com>]

Component drivers can prepare snd_pcm_hardware struct based on the hardware
capabilities which information should not be discarded.

Only touch the rates, channels_max and formats if they were left to 0,
otherwise keep the provided configuration intact for the parameter cross
checking decision.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
---
Hi,

Changes since RFC [1]:
- move the hw parameter initialization/preserve code inline to
  dpcm_runtime_setup_fe

this patch in essence extends the special casing of formats done by
083a25b18d6a ("ASoC: soc-pcm: fix hw->formats cleared by soc_pcm_hw_init() for dpcm")

Other parameters might have been set in the same way as the formats
and preserving these are equally important.

A case for this is SOF used with HDA codec (analog or more importantly, HDMI)
where the hw-> params are set based on the connected display/device and
should be preserved so we can report correct rate, format and channels
supported by the equipment.

If the hw-> parameters are left uninitialized then we still need to
set the UINT/ULLONG_MAX for the refining code to work.

This applies only for FE setup, in other cases we shall (as before) do
a full re-initialization.

I think this makes sense and I cannot think where this might flop, but
sent as RFC to see what people think. 

Br,
Peter

[1] https://lore.kernel.org/linux-sound/20251020073750.27784-1-peter.ujfalusi@linux.intel.com/

 sound/soc/soc-pcm.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 2c21fd528afd..0877daab7b38 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -1738,13 +1738,21 @@ static void dpcm_runtime_setup_fe(struct snd_pcm_substream *substream)
 	struct snd_pcm_hardware *hw = &runtime->hw;
 	struct snd_soc_dai *dai;
 	int stream = substream->stream;
-	u64 formats = hw->formats;
 	int i;
 
-	soc_pcm_hw_init(hw);
-
-	if (formats)
-		hw->formats &= formats;
+	/*
+	 * Initialize only pcm hardware patameters that has not been initialized
+	 * and preserve the configuration which might have been provided by
+	 * component drivers
+	 */
+	if (!hw->rates)
+		hw->rates = UINT_MAX;
+	if (!hw->rate_max)
+		hw->rate_max = UINT_MAX;
+	if (!hw->channels_max)
+		hw->channels_max = UINT_MAX;
+	if (!hw->formats)
+		hw->formats = ULLONG_MAX;
 
 	for_each_rtd_cpu_dais(fe, i, dai) {
 		const struct snd_soc_pcm_stream *cpu_stream;
-- 
2.51.1.dirty