[alsa-devel] [PATCH v1] ASoC: bcm2835: Remove redundant channel checking code in hw_params

[Matt Flax]

Due to channels_max and channels_min in the bcm2835_i2s_dai structure,
the channel guard code in bcm2835_i2s_hw_params is redundant.

The bcm2835_i2s_hw_params function checks that the channel count is
2 before continuing. This code never gets executed because core soc
checks prevent the execution (upon channel mismatch) of the
bcm2835_i2s_hw_params function.

The redundancy has been tested and checked for the case when
the bcm2835_i2s_dai structure has channels_max = 2 and a request
for 8 channels has been made. The test has confirmed that the
removed code is redundant as it never gets executed when a
channel mismatch occurs.

This redundant channel count check may seem like it will not cause
any problems however some sound cards (such as the 8 channel
AudioInjector Octo sound card) require the execution of the
bcm2835_i2s_hw_params function when channels_max in the
bcm2835_i2s_dai structure has been increased to 8.

As the channel checking code in bcm2835_i2s_hw_params is redundant
and stops certain cards from working it has been removed.

Signed-off-by: Matt Flax <flatmax at flatmax.org>
---
 sound/soc/bcm/bcm2835-i2s.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/sound/soc/bcm/bcm2835-i2s.c b/sound/soc/bcm/bcm2835-i2s.c
index 6ba2049..1773b83 100644
--- a/sound/soc/bcm/bcm2835-i2s.c
+++ b/sound/soc/bcm/bcm2835-i2s.c
@@ -310,15 +310,9 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
 	ch1pos = data_delay;
 	ch2pos = bclk_ratio / 2 + data_delay;
 
-	switch (params_channels(params)) {
-	case 2:
-		format = BCM2835_I2S_CH1(format) | BCM2835_I2S_CH2(format);
-		format |= BCM2835_I2S_CH1(BCM2835_I2S_CHPOS(ch1pos));
-		format |= BCM2835_I2S_CH2(BCM2835_I2S_CHPOS(ch2pos));
-		break;
-	default:
-		return -EINVAL;
-	}
+	format = BCM2835_I2S_CH1(format) | BCM2835_I2S_CH2(format);
+	format |= BCM2835_I2S_CH1(BCM2835_I2S_CHPOS(ch1pos));
+	format |= BCM2835_I2S_CH2(BCM2835_I2S_CHPOS(ch2pos));
 
 	/*
 	 * Set format for both streams.
-- 
2.7.4