Re: [PATCH] sound: sof: ioc4-topology: avoid extra dai_params copy

On 8/7/24 10:02, Arnd Bergmann wrote:

From: Arnd Bergmann arnd@arndb.de

The snd_pcm_hw_params structure is really too large to fit on the stack. Because of the way that clang inlines functions, it ends up twice in one function, which exceeds the 1024 byte limit for 32-bit architecutes:

sound/soc/sof/ipc4-topology.c:1700:1: error: stack frame size (1304) exceeds limit (1024) in 'sof_ipc4_prepare_copier_module' [-Werror,-Wframe-larger-than] sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget,

...

From what I can tell, this was unintentional, as both

sof_ipc4_prepare_dai_copier() and sof_ipc4_prepare_copier_module() make a copy for the same purpose, but copying it once has the exact same effect.

Humm, not sure. I think the copy was intentional so that if one of the fixups fails, then the initial hw_params structure is not modified.

Also not sure why a compiler would think inlining such a large function is a good idea?

Probably need Ranjani, Peter and Bard to comment on the format handling.

Remove the extra copy and change the direct struct assignment to an explicit memcpy() call to make it clearer to the reader that this is what happens. Note that gcc treats struct assignment as a memcpy() that may be inlined anyway, so the resulting object code is the same.

Fixes: f9209644ae76 ("ASoC: SOF: ipc4-topology: Correct DAI copier config and NHLT blob request") Signed-off-by: Arnd Bergmann arnd@arndb.de

---

sound/soc/sof/ipc4-topology.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/sound/soc/sof/ipc4-topology.c b/sound/soc/sof/ipc4-topology.c index 87be7f16e8c2..77f6850010f6 100644 --- a/sound/soc/sof/ipc4-topology.c +++ b/sound/soc/sof/ipc4-topology.c @@ -1651,7 +1651,6 @@ sof_ipc4_prepare_dai_copier(struct snd_sof_dev *sdev, struct snd_sof_dai *dai, struct snd_pcm_hw_params *params, int dir) { struct sof_ipc4_available_audio_format *available_fmt;

• struct snd_pcm_hw_params dai_params = *params; struct sof_ipc4_copier_data *copier_data; struct sof_ipc4_pin_format *pin_fmts; struct sof_ipc4_copier *ipc4_copier;

@@ -1676,7 +1675,7 @@ sof_ipc4_prepare_dai_copier(struct snd_sof_dev *sdev, struct snd_sof_dai *dai, num_pin_fmts = available_fmt->num_input_formats; }

• ret = sof_ipc4_adjust_params_to_dai_format(sdev, &dai_params, pin_fmts,

• ret = sof_ipc4_adjust_params_to_dai_format(sdev, params, pin_fmts, num_pin_fmts); if (ret) return ret;

@@ -1684,15 +1683,11 @@ sof_ipc4_prepare_dai_copier(struct snd_sof_dev *sdev, struct snd_sof_dai *dai, single_bitdepth = sof_ipc4_copier_is_single_bitdepth(sdev, pin_fmts, num_pin_fmts); ret = snd_sof_get_nhlt_endpoint_data(sdev, dai, single_bitdepth,

• 			     &dai_params,
  

• 			     params,
  		     ipc4_copier->dai_index,
  		     ipc4_copier->dai_type, dir,
  		     &ipc4_copier->copier_config,
  		     &copier_data->gtw_cfg.config_length);
  

• /* Update the params to reflect the changes made in this function */
• if (!ret)

• *params = dai_params;
  

• return ret;

}

@@ -1784,9 +1779,9 @@ sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget, * for capture. */ if (dir == SNDRV_PCM_STREAM_PLAYBACK)

• 	ref_params = *fe_params;
  

• 	memcpy(&ref_params, fe_params, sizeof(ref_params));
  

  else

• 	ref_params = *pipeline_params;
  

• 	memcpy(&ref_params, pipeline_params, sizeof(ref_params));
  
  

  copier_data->gtw_cfg.node_id &= ~SOF_IPC4_NODE_INDEX_MASK; copier_data->gtw_cfg.node_id |=

@@ -1819,7 +1814,7 @@ sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget, * In case of capture the ref_params returned will be used to * find the input configuration of the copier. */

• ref_params = *fe_params;
  

• memcpy(&ref_params, fe_params, sizeof(ref_params));
  

  ret = sof_ipc4_prepare_dai_copier(sdev, dai, &ref_params, dir); if (ret < 0) return ret;

@@ -1829,7 +1824,7 @@ sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget, * input configuration of the copier. */ if (dir == SNDRV_PCM_STREAM_PLAYBACK)

• 	ref_params = *pipeline_params;
  

• 	memcpy(&ref_params, pipeline_params, sizeof(ref_params));
  
  

  break; }

@@ -1838,7 +1833,7 @@ sof_ipc4_prepare_copier_module(struct snd_sof_widget *swidget, ipc4_copier = (struct sof_ipc4_copier *)swidget->private; copier_data = &ipc4_copier->data; available_fmt = &ipc4_copier->available_fmt;

• ref_params = *pipeline_params;
  

• memcpy(&ref_params, pipeline_params, sizeof(ref_params));
  
  

  break; }