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ASoC: stm32: sai: skip useless iterations on kernel rate loop

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the frequency of the kernel clock must be greater than or equal to the
bitclock rate. When searching for a convenient kernel clock rate in
stm32_sai_set_parent_rate() function, it is useless to continue the loop
below bitclock rate, as it will result in a invalid kernel clock rate.
Change the loop output condition.

Fixes: 2cfe1ff225 ("ASoC: stm32: sai: add stm32mp25 support")
Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
Link: https://patch.msgid.link/20250430165210.321273-2-olivier.moysan@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Olivier Moysan
2025-04-30 18:52:08 +02:00
committed by Mark Brown
parent b4432656b3
commit edea92770a
1 changed files with 7 additions and 4 deletions
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sound/soc/stm/stm32_sai_sub.c
+7 -4
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@@ -409,11 +409,11 @@ static int stm32_sai_set_parent_rate(struct stm32_sai_sub_data *sai,
unsigned int rate)
{
struct platform_device *pdev = sai->pdev;
unsigned int sai_ck_rate, sai_ck_max_rate, sai_curr_rate, sai_new_rate;
unsigned int sai_ck_rate, sai_ck_max_rate, sai_ck_min_rate, sai_curr_rate, sai_new_rate;
int div, ret;
/*
* Set maximum expected kernel clock frequency
* Set minimum and maximum expected kernel clock frequency
* - mclk on or spdif:
* f_sai_ck = MCKDIV * mclk-fs * fs
* Here typical 256 ratio is assumed for mclk-fs
@@ -423,13 +423,16 @@ static int stm32_sai_set_parent_rate(struct stm32_sai_sub_data *sai,
* Set constraint MCKDIV * FRL <= 256, to ensure MCKDIV is in available range
* f_sai_ck = sai_ck_max_rate * pow_of_two(FRL) / 256
*/
sai_ck_min_rate = rate * 256;
if (!(rate % SAI_RATE_11K))
sai_ck_max_rate = SAI_MAX_SAMPLE_RATE_11K * 256;
else
sai_ck_max_rate = SAI_MAX_SAMPLE_RATE_8K * 256;
if (!sai->sai_mclk && !STM_SAI_PROTOCOL_IS_SPDIF(sai))
if (!sai->sai_mclk && !STM_SAI_PROTOCOL_IS_SPDIF(sai)) {
sai_ck_min_rate = rate * sai->fs_length;
sai_ck_max_rate /= DIV_ROUND_CLOSEST(256, roundup_pow_of_two(sai->fs_length));
}
/*
* Request exclusivity, as the clock is shared by SAI sub-blocks and by
@@ -472,7 +475,7 @@ static int stm32_sai_set_parent_rate(struct stm32_sai_sub_data *sai,
/* Try a lower frequency */
div++;
sai_ck_rate = sai_ck_max_rate / div;
} while (sai_ck_rate > rate);
} while (sai_ck_rate >= sai_ck_min_rate);
/* No accurate rate found */
dev_err(&pdev->dev, "Failed to find an accurate rate");