Unverified Commit 1b1f491d authored by Peter Ujfalusi's avatar Peter Ujfalusi Committed by Mark Brown
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ASoC: SOF: Intel: hda-stream: Always use at least two BDLE for transfers 



The HDA specification states that the SDnLVI (Last Valid Index) must be at
least 1 (two BDLE entry).

Update the debug prints as well to provide better information.

While the LVI=0 worked so far without issues, it is better to align with
the specification to avoid unforeseen issues with FW loading.

Notes:
- The LVI > 0 rules is valid and honored for audio use cases
- LVI == 0 is used with software controlled (SPIB) transfers only for
  firmware and library loading, which is permitted by the hardware
- This is not spelled out in the specification and it is better to avoid
  cases

Signed-off-by: default avatarPeter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: default avatarLiam Girdwood <liam.r.girdwood@intel.com>
Reviewed-by: default avatarKai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: default avatarBard Liao <yung-chuan.liao@linux.intel.com>
Link: https://patch.msgid.link/20241107121532.3241-1-peter.ujfalusi@linux.intel.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 8121de33

sound/soc/sof/intel/hda-stream.c

+29 −3
Original line number Diff line number Diff line
@@ -119,10 +119,36 @@ int hda_dsp_stream_setup_bdl(struct snd_sof_dev *sdev, 
	int remain, ioc;



	period_bytes = hstream->period_bytes;

	dev_dbg(sdev->dev, "period_bytes:0x%x\n", period_bytes);

	if (!period_bytes)

	dev_dbg(sdev->dev, "period_bytes: %#x, bufsize: %#x\n", period_bytes,

		hstream->bufsize);



	if (!period_bytes) {

		unsigned int chunk_size;



		chunk_size = snd_sgbuf_get_chunk_size(dmab, 0, hstream->bufsize);



		period_bytes = hstream->bufsize;



		/*

		 * HDA spec demands that the LVI value must be at least one

		 * before the DMA operation can begin. This means that there

		 * must be at least two BDLE present for the transfer.

		 *

		 * If the buffer is not a single continuous area then the

		 * hda_setup_bdle() will create multiple BDLEs for each segment.

		 * If the memory is a single continuous area, force it to be

		 * split into two 'periods', otherwise the transfer will be

		 * split to multiple BDLE for each chunk in hda_setup_bdle()

		 *

		 * Note: period_bytes == 0 can only happen for firmware or

		 * library loading. The data size is 4K aligned, which ensures

		 * that the second chunk's start address will be 128-byte

		 * aligned.

		 */

		if (chunk_size == hstream->bufsize)

			period_bytes /= 2;

	}



	periods = hstream->bufsize / period_bytes;



	dev_dbg(sdev->dev, "periods: %d\n", periods);