intel: ssp: SSP rx start fixes #7564
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ujfalusi
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May 5, 2023
If DMA is active, do not read data directly from the SSP RX fifo. Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
If DMA transaction is ongoing when RX enabled, this leads to stuck communication between DMA and SSP. To avoid this, flush the RX fifo before enabling SSP RX. Link: thesofproject#7548 Suggested-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com> Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
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ujfalusi
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May 8, 2023
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| for (i = 0; read_ssdr && i < entries + 1; i++) | ||
| /* read to try empty fifo */ | ||
| ssp_read(dai, SSDR); |
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for readability I would be more explicit:
if (read_ssdr) {
/* read to try empty fifo */
for (i = 0; i < entries + 1; i++)
ssp_read(dai, SSDR);
}
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it's not just readability, there's no reason to test read_ssdr at every loop - though the compiler might be smart enough to move this up?
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Fixed in the mainline version #7577 -- will resubmit to stable-2.2 once merged.
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@kv2019i still needed ? |
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Link: #7548