This patch adds a new field to the dma_slave_caps struct which indicates the granularity with which the driver is able to update the residue field of the dma_tx_state struct. Making this information available to dmaengine users allows them to make better decisions on how to operate. E.g. for audio certain features like wakeup less operation or timer based scheduling only make sense and work correctly if the reported residue is fine-grained enough.

Right now four different levels of granularity are supported: * DESCRIPTOR: The DMA channel is only able to tell whether a descriptor has been completed or not, which means residue reporting is not supported by this channel. The residue field of the dma_tx_state field will always be 0. * SEGMENT: The DMA channel updates the residue field after each successfully completed segment of the transfer (For cyclic transfers this is after each period). This is typically implemented by having the hardware generate an interrupt after each transferred segment and then the drivers updates the outstanding residue by the size of the segment. Another possibility is if the hardware supports SG and the segment descriptor has a field which gets set after the segment has been completed. The driver then counts the number of segments without the flag set to compute the residue. * BURST: The DMA channel updates the residue field after each transferred burst. This is typically only supported if the hardware has a progress register of some sort (E.g. a register with the current read/write address or a register with the amount of bursts/beats/bytes that have been transferred or still need to be transferred).

Signed-off-by: Lars-Peter Clausen lars@metafoo.de Acked-by: Vinod Koul vinod.koul@intel.com --- Changes since v2: * Expanded the kernel doc documentation a bit Changes since v1: * Drop BYTE granularity level as there has been consent that it is not really useful. --- include/linux/dmaengine.h | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index ed92b30..bdaff45 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -364,6 +364,32 @@ struct dma_slave_config { unsigned int slave_id; };

+/** + * enum dma_residue_granularity - Granularity of the reported transfer residue + * @DMA_RESIDUE_GRANULARITY_DESCRIPTOR: Residue reporting is not support. The + * DMA channel is only able to tell whether a descriptor has been completed or + * not, which means residue reporting is not supported by this channel. The + * residue field of the dma_tx_state field will always be 0. + * @DMA_RESIDUE_GRANULARITY_SEGMENT: Residue is updated after each successfully + * completed segment of the transfer (For cyclic transfers this is after each + * period). This is typically implemented by having the hardware generate an + * interrupt after each transferred segment and then the drivers updates the + * outstanding residue by the size of the segment. Another possibility is if + * the hardware supports scatter-gather and the segment descriptor has a field + * which gets set after the segment has been completed. The driver then counts + * the number of segments without the flag set to compute the residue. + * @DMA_RESIDUE_GRANULARITY_BURST: Residue is updated after each transferred + * burst. This is typically only supported if the hardware has a progress + * register of some sort (E.g. a register with the current read/write address + * or a register with the amount of bursts/beats/bytes that have been + * transferred or still need to be transferred). + */ +enum dma_residue_granularity { + DMA_RESIDUE_GRANULARITY_DESCRIPTOR = 0, + DMA_RESIDUE_GRANULARITY_SEGMENT = 1, + DMA_RESIDUE_GRANULARITY_BURST = 2, +}; + /* struct dma_slave_caps - expose capabilities of a slave channel only * * @src_addr_widths: bit mask of src addr widths the channel supports @@ -374,6 +400,7 @@ struct dma_slave_config { * should be checked by controller as well * @cmd_pause: true, if pause and thereby resume is supported * @cmd_terminate: true, if terminate cmd is supported + * @residue_granularity: granularity of the reported transfer residue */ struct dma_slave_caps { u32 src_addr_widths; @@ -381,6 +408,7 @@ struct dma_slave_caps { u32 directions; bool cmd_pause; bool cmd_terminate; + enum dma_residue_granularity residue_granularity; };

static inline const char *dma_chan_name(struct dma_chan *chan)

Currently we have two different snd_soc_platform_driver structs in the generic dmaengine PCM driver. One for dmaengine drivers that support residue reporting and one for those which do not. When registering the PCM component we check whether the NO_RESIDUE flag is set or not and use the corresponding snd_soc_platform_driver. This patch modifies the driver to only have one snd_soc_platform_driver struct where the pointer() callback checks the NO_RESIDUE flag at runtime. This allows us to set the NO_RESIDUE flag after the PCM component has been registered. This becomes necessary when querying whether the dmaengine driver supports residue reporting from the dmaengine driver itself since the DMA channel might only be requested after the PCM component has been registered.

Signed-off-by: Lars-Peter Clausen lars@metafoo.de --- No changes since v2 New in v2 --- sound/soc/soc-generic-dmaengine-pcm.c | 39 ++++++++++++++--------------------- 1 file changed, 15 insertions(+), 24 deletions(-)

diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index 2a6c569..4e2bed8 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -248,6 +248,18 @@ err_free: return ret; }

+static snd_pcm_uframes_t dmaengine_pcm_pointer( + struct snd_pcm_substream *substream) +{ + struct snd_soc_pcm_runtime *rtd = substream->private_data; + struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform); + + if (pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE) + return snd_dmaengine_pcm_pointer_no_residue(substream); + else + return snd_dmaengine_pcm_pointer(substream); +} + static const struct snd_pcm_ops dmaengine_pcm_ops = { .open = dmaengine_pcm_open, .close = snd_dmaengine_pcm_close, @@ -255,7 +267,7 @@ static const struct snd_pcm_ops dmaengine_pcm_ops = { .hw_params = dmaengine_pcm_hw_params, .hw_free = snd_pcm_lib_free_pages, .trigger = snd_dmaengine_pcm_trigger, - .pointer = snd_dmaengine_pcm_pointer, + .pointer = dmaengine_pcm_pointer, };

static const struct snd_soc_platform_driver dmaengine_pcm_platform = { @@ -265,23 +277,6 @@ static const struct snd_soc_platform_driver dmaengine_pcm_platform = { .probe_order = SND_SOC_COMP_ORDER_LATE, };

-static const struct snd_pcm_ops dmaengine_no_residue_pcm_ops = { - .open = dmaengine_pcm_open, - .close = snd_dmaengine_pcm_close, - .ioctl = snd_pcm_lib_ioctl, - .hw_params = dmaengine_pcm_hw_params, - .hw_free = snd_pcm_lib_free_pages, - .trigger = snd_dmaengine_pcm_trigger, - .pointer = snd_dmaengine_pcm_pointer_no_residue, -}; - -static const struct snd_soc_platform_driver dmaengine_no_residue_pcm_platform = { - .ops = &dmaengine_no_residue_pcm_ops, - .pcm_new = dmaengine_pcm_new, - .pcm_free = dmaengine_pcm_free, - .probe_order = SND_SOC_COMP_ORDER_LATE, -}; - static const char * const dmaengine_pcm_dma_channel_names[] = { [SNDRV_PCM_STREAM_PLAYBACK] = "tx", [SNDRV_PCM_STREAM_CAPTURE] = "rx", @@ -374,12 +369,8 @@ int snd_dmaengine_pcm_register(struct device *dev, if (ret) goto err_free_dma;

- if (flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE) - ret = snd_soc_add_platform(dev, &pcm->platform, - &dmaengine_no_residue_pcm_platform); - else - ret = snd_soc_add_platform(dev, &pcm->platform, - &dmaengine_pcm_platform); + ret = snd_soc_add_platform(dev, &pcm->platform, + &dmaengine_pcm_platform); if (ret) goto err_free_dma;

The pl330 driver properly reports that it does not have residue reporting support, which means the PCM dmanegine driver is able to figure this out on its own. So there is no need to set the flag manually. Removing the flag has the advantage that once the pl330 driver gains support for residue reporting it will automatically be used by the generic dmaengine PCM driver.

Signed-off-by: Lars-Peter Clausen lars@metafoo.de --- No changes since v2 New in v2 --- sound/soc/adi/axi-i2s.c | 3 +-- sound/soc/adi/axi-spdif.c | 3 +-- 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/sound/soc/adi/axi-i2s.c b/sound/soc/adi/axi-i2s.c index 7f91a86..6058c1f 100644 --- a/sound/soc/adi/axi-i2s.c +++ b/sound/soc/adi/axi-i2s.c @@ -236,8 +236,7 @@ static int axi_i2s_probe(struct platform_device *pdev) if (ret) goto err_clk_disable;

- ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, - SND_DMAENGINE_PCM_FLAG_NO_RESIDUE); + ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, 0); if (ret) goto err_clk_disable;

diff --git a/sound/soc/adi/axi-spdif.c b/sound/soc/adi/axi-spdif.c index 8db7a99..198e3a4 100644 --- a/sound/soc/adi/axi-spdif.c +++ b/sound/soc/adi/axi-spdif.c @@ -229,8 +229,7 @@ static int axi_spdif_probe(struct platform_device *pdev) if (ret) goto err_clk_disable;

- ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, - SND_DMAENGINE_PCM_FLAG_NO_RESIDUE); + ret = devm_snd_dmaengine_pcm_register(&pdev->dev, NULL, 0); if (ret) goto err_clk_disable;