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Subject[PATCH 3.19 65/75] spi: dw-mid: clear BUSY flag fist and test other one
Date
3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

commit 854d2f241d71f6ca08ccde30e6c7c2e403363e52 upstream.

The logic of DMA completion is broken now since test_and_clear_bit() never
returns the other bit is set. It means condition are always false and we have
spi_finalize_current_transfer() called per each DMA completion which is wrong.

The patch fixes logic by clearing BUSY bit first and then check for the other
one.

Fixes: 30c8eb52cc4a (spi: dw-mid: split rx and tx callbacks when DMA)
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/spi/spi-dw-mid.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/spi/spi-dw-mid.c
+++ b/drivers/spi/spi-dw-mid.c
@@ -108,7 +108,8 @@ static void dw_spi_dma_tx_done(void *arg
{
struct dw_spi *dws = arg;

- if (test_and_clear_bit(TX_BUSY, &dws->dma_chan_busy) & BIT(RX_BUSY))
+ clear_bit(TX_BUSY, &dws->dma_chan_busy);
+ if (test_bit(RX_BUSY, &dws->dma_chan_busy))
return;
dw_spi_xfer_done(dws);
}
@@ -156,7 +157,8 @@ static void dw_spi_dma_rx_done(void *arg
{
struct dw_spi *dws = arg;

- if (test_and_clear_bit(RX_BUSY, &dws->dma_chan_busy) & BIT(TX_BUSY))
+ clear_bit(RX_BUSY, &dws->dma_chan_busy);
+ if (test_bit(TX_BUSY, &dws->dma_chan_busy))
return;
dw_spi_xfer_done(dws);
}



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