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drivers: i2s_sam_ssc: fix cache coherency in dma_rx_callback

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Invalidate the cache before the RX data block is passed to the DMA
engine and not after it is received. If the RX data block contains
dirty cache lines they can be flushed anytime, overwriting legitimate
data that have been prefilled by the DMA module.

Signed-off-by: Piotr Mienkowski <piotr.mienkowski@gmail.com>
This commit is contained in:
Piotr Mienkowski 2022-01-26 23:24:40 +01:00 • committed by Carles Cufí
commit 1ed5ba7720
1 changed files with 3 additions and 3 deletions
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6
drivers/i2s/i2s_sam_ssc.c
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@ -220,9 +220,6 @@ static void dma_rx_callback(const struct device *dma_dev, void *user_data,
goto rx_disable;
}
/* Assure cache coherency after DMA write operation */
DCACHE_INVALIDATE(stream->mem_block, stream->cfg.block_size);
/* All block data received */
ret = queue_put(&stream->mem_block_queue, stream->mem_block,
stream->cfg.block_size);
@ -247,6 +244,9 @@ static void dma_rx_callback(const struct device *dma_dev, void *user_data,
goto rx_disable;
}
/* Assure cache coherency before DMA write operation */
DCACHE_INVALIDATE(stream->mem_block, stream->cfg.block_size);
ret = reload_dma(dev_cfg->dev_dma, stream->dma_channel,
(void *)&(ssc->SSC_RHR), stream->mem_block,
stream->cfg.block_size);