spi: dw-dma: Fail DMA-based transfer if no Tx-buffer specified

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Since commit 46164fde6b ("spi: dw: Fix Rx-only DMA transfers") if DMA
interface is enabled, then Tx-buffer must be available in each SPI
transfer. It's required since in order to activate the incoming data
reception either DMA or CPU must be pushing data out to the SPI bus.
But the DW APB SSI DMA driver code is still left in state as if Tx-buffer
might be optional, which is no longer true. Let's fix it so an error would
be returned if no Tx-buffer detected and DMA Tx would be always
enabled.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200920112322.24585-3-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Mark Brown <broonie@kernel.org>

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Serge Semin 2020-09-20 14:23:13 +03:00 • committed by Mark Brown

parent 01ddbbb0b0

commit 7ef30385b0

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1 changed files with 13 additions and 14 deletions

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drivers/spi/spi-dw-dma.c

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