ASoC: SOF: Intel: reserve link DMA for sdw bpt stream

Merge series from Bard Liao <[e-mail]>:

Currently, hda_sdw_bpt_dma_prepare() get a HDA stream and use the link
DMA but doesn't reserve it. It works fine because we assume the
SwoundWire BPT will not run with audio streams simultaneously. Create
and use the new helpers to reserve the link DMA and allow running BPT
and audio stream simultaneously.

Pierre adds:

For the record this solution has two issues not documented in any commit
message:

a) this will not work in 'dspless' mode, where the link DMA is not
enabled. That's probably fine given that no one used that mode in
production, but that's a software restriction that you will not be able
to undo.

b) this raise the question of how bandwidth will be managed. The premise
of BPT is that it uses all the bus bandwidth to guarantee predictable
firmware download times. If the available bandwidth is restricted by
other audio streams, then mechanically the startup latency will be
increased and vary - or you will have to run the bus at a higher
frequency to provision enough bandwidth for BPT but that means higher
power consumption. Or you will have to change the bus clock dynamically
which is possible at the hardware level for SDCA parts but not legacy
ones.

I am not going to lay on the tracks for this low-level set of changes,
but you'll have to address the b) opens for future contributions.

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

···
 	       struct snd_dma_buffer *dmab, bool persistent_buffer, int direction,
 	       bool is_iccmax)
 {
-	struct snd_sof_dev *sdev = dev_get_drvdata(dev);
-	struct hdac_ext_stream *hext_stream;
-	struct hdac_stream *hstream;
-	int ret;
-
-	hext_stream = hda_dsp_stream_get(sdev, direction, 0);
-
-	if (!hext_stream) {
-		dev_err(sdev->dev, "error: no stream available\n");
-		return ERR_PTR(-ENODEV);
-	}
-	hstream = &hext_stream->hstream;
-	hstream->substream = NULL;
-
-	/*
-	 * Allocate DMA buffer if it is temporary or if the buffer is intended
-	 * to be persistent but not yet allocated.
-	 * We cannot rely solely on !dmab->area as caller might use a struct on
-	 * stack (when it is temporary) without clearing it to 0.
-	 */
-	if (!persistent_buffer || !dmab->area) {
-		ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV_SG, dev, size, dmab);
-		if (ret < 0) {
-			dev_err(sdev->dev, "%s: memory alloc failed: %d\n",
-				__func__, ret);
-			goto out_put;
-		}
-	}
-
-	hstream->period_bytes = 0;/* initialize period_bytes */
-	hstream->format_val = format;
-	hstream->bufsize = size;
-
-	if (is_iccmax) {
-		ret = hda_dsp_iccmax_stream_hw_params(sdev, hext_stream, dmab, NULL);
-		if (ret < 0) {
-			dev_err(sdev->dev, "error: iccmax stream prepare failed: %d\n", ret);
-			goto out_free;
-		}
-	} else {
-		ret = hda_dsp_stream_hw_params(sdev, hext_stream, dmab, NULL);
-		if (ret < 0) {
-			dev_err(sdev->dev, "error: hdac prepare failed: %d\n", ret);
-			goto out_free;
-		}
-		hda_dsp_stream_spib_config(sdev, hext_stream, HDA_DSP_SPIB_ENABLE, size);
-	}
-
-	return hext_stream;
-
-out_free:
-	snd_dma_free_pages(dmab);
-	dmab->area = NULL;
-	dmab->bytes = 0;
-	hstream->bufsize = 0;
-	hstream->format_val = 0;
-out_put:
-	hda_dsp_stream_put(sdev, direction, hstream->stream_tag);
-	return ERR_PTR(ret);
+	return hda_data_stream_prepare(dev, format, size, dmab, persistent_buffer,
+				       direction, is_iccmax, false);
 }
 EXPORT_SYMBOL_NS(hda_cl_prepare, "SND_SOC_SOF_INTEL_HDA_COMMON");
 
···
 int hda_cl_cleanup(struct device *dev, struct snd_dma_buffer *dmab,
 			  bool persistent_buffer, struct hdac_ext_stream *hext_stream)
 {
-	struct snd_sof_dev *sdev =  dev_get_drvdata(dev);
-	struct hdac_stream *hstream = &hext_stream->hstream;
-	int sd_offset = SOF_STREAM_SD_OFFSET(hstream);
-	int ret = 0;
-
-	if (hstream->direction == SNDRV_PCM_STREAM_PLAYBACK)
-		ret = hda_dsp_stream_spib_config(sdev, hext_stream, HDA_DSP_SPIB_DISABLE, 0);
-	else
-		snd_sof_dsp_update_bits(sdev, HDA_DSP_HDA_BAR, sd_offset,
-					SOF_HDA_SD_CTL_DMA_START, 0);
-
-	hda_dsp_stream_put(sdev, hstream->direction, hstream->stream_tag);
-	hstream->running = 0;
-	hstream->substream = NULL;
-
-	/* reset BDL address */
-	snd_sof_dsp_write(sdev, HDA_DSP_HDA_BAR,
-			  sd_offset + SOF_HDA_ADSP_REG_SD_BDLPL, 0);
-	snd_sof_dsp_write(sdev, HDA_DSP_HDA_BAR,
-			  sd_offset + SOF_HDA_ADSP_REG_SD_BDLPU, 0);
-
-	snd_sof_dsp_write(sdev, HDA_DSP_HDA_BAR, sd_offset, 0);
-
-	if (!persistent_buffer) {
-		snd_dma_free_pages(dmab);
-		dmab->area = NULL;
-		dmab->bytes = 0;
-		hstream->bufsize = 0;
-		hstream->format_val = 0;
-	}
-
-	return ret;
+	return hda_data_stream_cleanup(dev, dmab, persistent_buffer, hext_stream, false);
 }
 EXPORT_SYMBOL_NS(hda_cl_cleanup, "SND_SOC_SOF_INTEL_HDA_COMMON");
 

sound/soc/sof/intel/hda-sdw-bpt.c

···
 
 	dev_dbg(dev, "direction %d format_val %#x\n", direction, format);
 
-	bpt_stream = hda_cl_prepare(dev, format, bpt_num_bytes, dmab_bdl, false, direction, false);
+	bpt_stream = hda_data_stream_prepare(dev, format, bpt_num_bytes, dmab_bdl,
+					     false, direction, false, true);
 	if (IS_ERR(bpt_stream)) {
 		dev_err(sdev->dev, "%s: SDW BPT DMA prepare failed: dir %d\n",
 			__func__, direction);
···
 	u32 mask;
 	int ret;
 
-	ret = hda_cl_cleanup(sdev->dev, dmab_bdl, false, sdw_bpt_stream);
+	ret = hda_data_stream_cleanup(sdev->dev, dmab_bdl, false, sdw_bpt_stream, true);
 	if (ret < 0) {
 		dev_err(sdev->dev, "%s: SDW BPT DMA cleanup failed\n",
 			__func__);

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

···
 }
 
 /* get next unused stream */
-struct hdac_ext_stream *
-hda_dsp_stream_get(struct snd_sof_dev *sdev, int direction, u32 flags)
+static struct hdac_ext_stream *
+_hda_dsp_stream_get(struct snd_sof_dev *sdev, int direction, u32 flags, bool pair)
 {
 	const struct sof_intel_dsp_desc *chip_info =  get_chip_info(sdev->pdata);
 	struct sof_intel_hda_dev *hda = sdev->pdata->hw_pdata;
···
 			if (hda_stream->host_reserved)
 				continue;
 
+			if (pair && hext_stream->link_locked)
+				continue;
+
 			s->opened = true;
+
+			if (pair)
+				hext_stream->link_locked = true;
+
 			break;
 		}
 	}
···
 	return hext_stream;
 }
 
+struct hdac_ext_stream *
+hda_dsp_stream_get(struct snd_sof_dev *sdev, int direction, u32 flags)
+{
+	return _hda_dsp_stream_get(sdev, direction, flags, false);
+}
+
+struct hdac_ext_stream *
+hda_dsp_stream_pair_get(struct snd_sof_dev *sdev, int direction, u32 flags)
+{
+	return _hda_dsp_stream_get(sdev, direction, flags, true);
+}
+
 /* free a stream */
-int hda_dsp_stream_put(struct snd_sof_dev *sdev, int direction, int stream_tag)
+static int _hda_dsp_stream_put(struct snd_sof_dev *sdev, int direction, int stream_tag, bool pair)
 {
 	const struct sof_intel_dsp_desc *chip_info =  get_chip_info(sdev->pdata);
 	struct sof_intel_hda_dev *hda = sdev->pdata->hw_pdata;
 	struct hdac_bus *bus = sof_to_bus(sdev);
 	struct sof_intel_hda_stream *hda_stream;
 	struct hdac_ext_stream *hext_stream;
+	struct hdac_ext_stream *link_stream;
 	struct hdac_stream *s;
 	bool dmi_l1_enable = true;
 	bool found = false;
···
 		if (s->direction == direction && s->stream_tag == stream_tag) {
 			s->opened = false;
 			found = true;
+			if (pair)
+				link_stream = hext_stream;
 		} else if (!(hda_stream->flags & SOF_HDA_STREAM_DMI_L1_COMPATIBLE)) {
 			dmi_l1_enable = false;
 		}
···
 		return -ENODEV;
 	}
 
+	if (pair)
+		snd_hdac_ext_stream_release(link_stream, HDAC_EXT_STREAM_TYPE_LINK);
+
 	return 0;
+}
+
+int hda_dsp_stream_put(struct snd_sof_dev *sdev, int direction, int stream_tag)
+{
+	return _hda_dsp_stream_put(sdev, direction, stream_tag, false);
+}
+
+int hda_dsp_stream_pair_put(struct snd_sof_dev *sdev, int direction, int stream_tag)
+{
+	return _hda_dsp_stream_put(sdev, direction, stream_tag, true);
 }
 
 static int hda_dsp_stream_reset(struct snd_sof_dev *sdev, struct hdac_stream *hstream)
···
 	return ((u64)ldp_u << 32) | ldp_l;
 }
 EXPORT_SYMBOL_NS(hda_dsp_get_stream_ldp, "SND_SOC_SOF_INTEL_HDA_COMMON");
+
+struct hdac_ext_stream *
+hda_data_stream_prepare(struct device *dev, unsigned int format, unsigned int size,
+			struct snd_dma_buffer *dmab, bool persistent_buffer, int direction,
+			bool is_iccmax, bool pair)
+{
+	struct snd_sof_dev *sdev = dev_get_drvdata(dev);
+	struct hdac_ext_stream *hext_stream;
+	struct hdac_stream *hstream;
+	int ret;
+
+	if (pair)
+		hext_stream = hda_dsp_stream_pair_get(sdev, direction, 0);
+	else
+		hext_stream = hda_dsp_stream_get(sdev, direction, 0);
+
+	if (!hext_stream) {
+		dev_err(sdev->dev, "%s: no stream available\n", __func__);
+		return ERR_PTR(-ENODEV);
+	}
+	hstream = &hext_stream->hstream;
+	hstream->substream = NULL;
+
+	/*
+	 * Allocate DMA buffer if it is temporary or if the buffer is intended
+	 * to be persistent but not yet allocated.
+	 * We cannot rely solely on !dmab->area as caller might use a struct on
+	 * stack (when it is temporary) without clearing it to 0.
+	 */
+	if (!persistent_buffer || !dmab->area) {
+		ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV_SG, dev, size, dmab);
+		if (ret < 0) {
+			dev_err(sdev->dev, "%s: memory alloc failed: %d\n",
+				__func__, ret);
+			goto out_put;
+		}
+	}
+
+	hstream->period_bytes = 0; /* initialize period_bytes */
+	hstream->format_val = format;
+	hstream->bufsize = size;
+
+	if (is_iccmax) {
+		ret = hda_dsp_iccmax_stream_hw_params(sdev, hext_stream, dmab, NULL);
+		if (ret < 0) {
+			dev_err(sdev->dev, "%s: iccmax stream prepare failed: %d\n",
+				__func__, ret);
+			goto out_free;
+		}
+	} else {
+		ret = hda_dsp_stream_hw_params(sdev, hext_stream, dmab, NULL);
+		if (ret < 0) {
+			dev_err(sdev->dev, "%s: hdac prepare failed: %d\n", __func__, ret);
+			goto out_free;
+		}
+		hda_dsp_stream_spib_config(sdev, hext_stream, HDA_DSP_SPIB_ENABLE, size);
+	}
+
+	return hext_stream;
+
+out_free:
+	snd_dma_free_pages(dmab);
+	dmab->area = NULL;
+	dmab->bytes = 0;
+	hstream->bufsize = 0;
+	hstream->format_val = 0;
+out_put:
+	if (pair)
+		hda_dsp_stream_pair_put(sdev, direction, hstream->stream_tag);
+	else
+		hda_dsp_stream_put(sdev, direction, hstream->stream_tag);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_NS(hda_data_stream_prepare, "SND_SOC_SOF_INTEL_HDA_COMMON");
+
+int hda_data_stream_cleanup(struct device *dev, struct snd_dma_buffer *dmab,
+			    bool persistent_buffer, struct hdac_ext_stream *hext_stream, bool pair)
+{
+	struct snd_sof_dev *sdev =  dev_get_drvdata(dev);
+	struct hdac_stream *hstream = hdac_stream(hext_stream);
+	int sd_offset = SOF_STREAM_SD_OFFSET(hstream);
+	int ret = 0;
+
+	if (hstream->direction == SNDRV_PCM_STREAM_PLAYBACK)
+		ret = hda_dsp_stream_spib_config(sdev, hext_stream, HDA_DSP_SPIB_DISABLE, 0);
+	else
+		snd_sof_dsp_update_bits(sdev, HDA_DSP_HDA_BAR, sd_offset,
+					SOF_HDA_SD_CTL_DMA_START, 0);
+
+	if (pair)
+		hda_dsp_stream_pair_put(sdev, hstream->direction, hstream->stream_tag);
+	else
+		hda_dsp_stream_put(sdev, hstream->direction, hstream->stream_tag);
+
+	hstream->running = 0;
+	hstream->substream = NULL;
+
+	/* reset BDL address */
+	snd_sof_dsp_write(sdev, HDA_DSP_HDA_BAR,
+			  sd_offset + SOF_HDA_ADSP_REG_SD_BDLPL, 0);
+	snd_sof_dsp_write(sdev, HDA_DSP_HDA_BAR,
+			  sd_offset + SOF_HDA_ADSP_REG_SD_BDLPU, 0);
+
+	snd_sof_dsp_write(sdev, HDA_DSP_HDA_BAR, sd_offset, 0);
+
+	if (!persistent_buffer) {
+		snd_dma_free_pages(dmab);
+		dmab->area = NULL;
+		dmab->bytes = 0;
+		hstream->bufsize = 0;
+		hstream->format_val = 0;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_NS(hda_data_stream_cleanup, "SND_SOC_SOF_INTEL_HDA_COMMON");

sound/soc/sof/intel/hda.h

···
 
 struct hdac_ext_stream *
 	hda_dsp_stream_get(struct snd_sof_dev *sdev, int direction, u32 flags);
+struct hdac_ext_stream *
+	hda_dsp_stream_pair_get(struct snd_sof_dev *sdev, int direction, u32 flags);
 int hda_dsp_stream_put(struct snd_sof_dev *sdev, int direction, int stream_tag);
+int hda_dsp_stream_pair_put(struct snd_sof_dev *sdev, int direction, int stream_tag);
 int hda_dsp_stream_spib_config(struct snd_sof_dev *sdev,
 			       struct hdac_ext_stream *hext_stream,
 			       int enable, u32 size);
···
 
 int sdw_hda_dai_trigger(struct snd_pcm_substream *substream, int cmd,
 			struct snd_soc_dai *cpu_dai);
+
+struct hdac_ext_stream *
+hda_data_stream_prepare(struct device *dev, unsigned int format, unsigned int size,
+			struct snd_dma_buffer *dmab, bool persistent_buffer, int direction,
+			bool is_iccmax, bool pair);
+
+int hda_data_stream_cleanup(struct device *dev, struct snd_dma_buffer *dmab,
+			    bool persistent_buffer, struct hdac_ext_stream *hext_stream, bool pair);
 
 /* common dai driver */
 extern struct snd_soc_dai_driver skl_dai[];