From: Codrin Ciubotariu codrin.ciubotariu@microchip.com

The period size represents the size of the DMA descriptor. To ensure all DMA descriptors start from a well-aligned address, the period size must be divided by (sample size * maxburst), not just by maxburst. This adjustment allows for computing a higher maxburst value, thereby increasing the performance of the DMA transfer. Previously, snd_pcm_lib_period_bytes() returned 0 because the runtime HW parameters are computed after the hw_params() callbacks are used. To address this, we now use params_*() functions to compute the period size accurately. This change optimizes the DMA transfer performance by ensuring proper alignment and efficient use of maxburst values.

Signed-off-by: Codrin Ciubotariu codrin.ciubotariu@microchip.com [andrei.simion@microchip.com: Reword commit message and commit title. Add macros with values for maximum DMA chunk size allowed. Add DMA_BURST_ALIGNED preprocessor function to check the alignment of the DMA burst] Signed-off-by: Andrei Simion andrei.simion@microchip.com --- sound/soc/atmel/mchp-i2s-mcc.c | 38 +++++++++++++++++++++++++++++----- 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/sound/soc/atmel/mchp-i2s-mcc.c b/sound/soc/atmel/mchp-i2s-mcc.c index 193dd7acceb0..35a56b266b8d 100644 --- a/sound/soc/atmel/mchp-i2s-mcc.c +++ b/sound/soc/atmel/mchp-i2s-mcc.c @@ -221,6 +221,15 @@ #define MCHP_I2SMCC_MAX_CHANNELS 8 #define MCHP_I2MCC_TDM_SLOT_WIDTH 32

+/* + * ---- DMA chunk size allowed ---- + */ +#define MCHP_I2SMCC_DMA_8_WORD_CHUNK 8 +#define MCHP_I2SMCC_DMA_4_WORD_CHUNK 4 +#define MCHP_I2SMCC_DMA_2_WORD_CHUNK 2 +#define MCHP_I2SMCC_DMA_1_WORD_CHUNK 1 +#define DMA_BURST_ALIGNED(_p, _s, _w) !(_p % (_s * _w)) + static const struct regmap_config mchp_i2s_mcc_regmap_config = { .reg_bits = 32, .reg_stride = 4, @@ -504,12 +513,30 @@ static int mchp_i2s_mcc_is_running(struct mchp_i2s_mcc_dev *dev) return !!(sr & (MCHP_I2SMCC_SR_TXEN | MCHP_I2SMCC_SR_RXEN)); }

+static inline int mchp_i2s_mcc_period_to_maxburst(int period_size, int sample_size) +{ + int p_size = period_size; + int s_size = sample_size; + + if (DMA_BURST_ALIGNED(p_size, s_size, MCHP_I2SMCC_DMA_8_WORD_CHUNK)) + return MCHP_I2SMCC_DMA_8_WORD_CHUNK; + if (DMA_BURST_ALIGNED(p_size, s_size, MCHP_I2SMCC_DMA_4_WORD_CHUNK)) + return MCHP_I2SMCC_DMA_4_WORD_CHUNK; + if (DMA_BURST_ALIGNED(p_size, s_size, MCHP_I2SMCC_DMA_2_WORD_CHUNK)) + return MCHP_I2SMCC_DMA_2_WORD_CHUNK; + return MCHP_I2SMCC_DMA_1_WORD_CHUNK; +} + static int mchp_i2s_mcc_hw_params(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *params, struct snd_soc_dai *dai) { unsigned long rate = 0; struct mchp_i2s_mcc_dev *dev = snd_soc_dai_get_drvdata(dai); + int sample_bytes = params_physical_width(params) / 8; + int period_bytes = params_period_size(params) * + params_channels(params) * sample_bytes; + int maxburst; u32 mra = 0; u32 mrb = 0; unsigned int channels = params_channels(params); @@ -519,9 +546,9 @@ static int mchp_i2s_mcc_hw_params(struct snd_pcm_substream *substream, int ret; bool is_playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);

- dev_dbg(dev->dev, "%s() rate=%u format=%#x width=%u channels=%u\n", + dev_dbg(dev->dev, "%s() rate=%u format=%#x width=%u channels=%u period_bytes=%d\n", __func__, params_rate(params), params_format(params), - params_width(params), params_channels(params)); + params_width(params), params_channels(params), period_bytes);

switch (dev->fmt & SND_SOC_DAIFMT_FORMAT_MASK) { case SND_SOC_DAIFMT_I2S: @@ -630,11 +657,12 @@ static int mchp_i2s_mcc_hw_params(struct snd_pcm_substream *substream, * We must have the same burst size configured * in the DMA transfer and in out IP */ - mrb |= MCHP_I2SMCC_MRB_DMACHUNK(channels); + maxburst = mchp_i2s_mcc_period_to_maxburst(period_bytes, sample_bytes); + mrb |= MCHP_I2SMCC_MRB_DMACHUNK(maxburst); if (is_playback) - dev->playback.maxburst = 1 << (fls(channels) - 1); + dev->playback.maxburst = maxburst; else - dev->capture.maxburst = 1 << (fls(channels) - 1); + dev->capture.maxburst = maxburst;

switch (params_format(params)) { case SNDRV_PCM_FORMAT_S8:

base-commit: fdadd93817f124fd0ea6ef251d4a1068b7feceba