From: Matt Flax <flatmax@flatmax.org>
Cc: alsa-devel@alsa-project.org, Mark Brown <broonie@kernel.org>,
linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH] ASoC: bcm2835-i2s: substream alignment now independent in hwparams
Date: Fri, 27 Mar 2020 11:30:50 +1100 [thread overview]
Message-ID: <1dcf128a-4ad3-0efa-81e4-b3ccc7caa8f1@flatmax.org> (raw)
In-Reply-To: <d0684926-3f7a-0b97-a298-4088925442a4@flatmax.org>
On 27/3/20 10:56 am, Matt Flax wrote:
>
> Should this patch be handled through the ALSA team the R. Pi team or
> the BCM team ?
>
Resending again with reduced recipients.
>
> thanks
>
> Matt
>
> On 24/3/20 8:08 pm, Matt Flax wrote:
>> Substream sample alignment was being set in hwparams for both
>> substreams at the same time. This became a problem when the Audio
>> Injector isolated sound card needed to offset sample alignment
>> for high sample rates. The latency difference between playback
>> and capture occurs because of the digital isolation chip
>> propagation time, particularly when the codec is master and
>> the DAC return is twice delayed.
>>
>> This patch sets sample alignment registers based on the substream
>> direction in hwparams. This gives the machine driver more control
>> over sample alignment in the bcm2835 i2s driver.
>>
>> Signed-off-by: Matt Flax <flatmax@flatmax.org>
>> ---
>> sound/soc/bcm/bcm2835-i2s.c | 36 +++++++++++++++++++-----------------
>> 1 file changed, 19 insertions(+), 17 deletions(-)
>>
>> diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c
>> index e6a12e271b07..9db542699a13 100644
>> --- a/sound/soc/bcm/bcm2835-i2s.c
>> +++ b/sound/soc/bcm/bcm2835-i2s.c
>> @@ -493,11 +493,6 @@ static int bcm2835_i2s_hw_params(struct
>> snd_pcm_substream *substream,
>> return -EINVAL;
>> }
>> - bcm2835_i2s_calc_channel_pos(&rx_ch1_pos, &rx_ch2_pos,
>> - rx_mask, slot_width, data_delay, odd_slot_offset);
>> - bcm2835_i2s_calc_channel_pos(&tx_ch1_pos, &tx_ch2_pos,
>> - tx_mask, slot_width, data_delay, odd_slot_offset);
>> -
>> /*
>> * Transmitting data immediately after frame start, eg
>> * in left-justified or DSP mode A, only works stable
>> @@ -508,19 +503,26 @@ static int bcm2835_i2s_hw_params(struct
>> snd_pcm_substream *substream,
>> "Unstable slave config detected, L/R may be swapped");
>> /*
>> - * Set format for both streams.
>> - * We cannot set another frame length
>> - * (and therefore word length) anyway,
>> - * so the format will be the same.
>> + * Set format on a per stream basis.
>> + * The alignment format can be different depending on direction.
>> */
>> - regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG,
>> - format
>> - | BCM2835_I2S_CH1_POS(rx_ch1_pos)
>> - | BCM2835_I2S_CH2_POS(rx_ch2_pos));
>> - regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG,
>> - format
>> - | BCM2835_I2S_CH1_POS(tx_ch1_pos)
>> - | BCM2835_I2S_CH2_POS(tx_ch2_pos));
>> + if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
>> + bcm2835_i2s_calc_channel_pos(&rx_ch1_pos, &rx_ch2_pos,
>> + rx_mask, slot_width, data_delay, odd_slot_offset);
>> + regmap_write(dev->i2s_regmap, BCM2835_I2S_RXC_A_REG,
>> + format
>> + | BCM2835_I2S_CH1_POS(rx_ch1_pos)
>> + | BCM2835_I2S_CH2_POS(rx_ch2_pos));
>> + }
>> +
>> + if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
>> + bcm2835_i2s_calc_channel_pos(&tx_ch1_pos, &tx_ch2_pos,
>> + tx_mask, slot_width, data_delay, odd_slot_offset);
>> + regmap_write(dev->i2s_regmap, BCM2835_I2S_TXC_A_REG,
>> + format
>> + | BCM2835_I2S_CH1_POS(tx_ch1_pos)
>> + | BCM2835_I2S_CH2_POS(tx_ch2_pos));
>> + }
>> /* Setup the I2S mode */
next prev parent reply other threads:[~2020-03-27 0:31 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 9:08 [PATCH] ASoC: bcm2835-i2s: substream alignment now independent in hwparams Matt Flax
2020-03-24 9:08 ` Matt Flax
2020-03-24 9:08 ` Matt Flax
2020-03-26 23:56 ` Matt Flax
2020-03-26 23:56 ` Matt Flax
2020-03-26 23:56 ` Matt Flax
2020-03-27 0:30 ` Matt Flax [this message]
2020-03-27 13:23 ` Matthias Reichl
2020-03-27 21:50 ` Matt Flax
2020-03-28 11:59 ` Matthias Reichl
2020-03-28 23:47 ` Matt Flax
2020-03-29 11:01 ` Matthias Reichl
2020-03-27 13:07 ` Mark Brown
2020-03-27 13:07 ` Mark Brown
2020-03-27 13:07 ` Mark Brown
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