spi: dw-dma: Set DMA Level registers on init
Indeed the registers content doesn't get cleared when the SPI controller is disabled and enabled. Max burst lengths aren't changed since the Rx and Tx DMA channels are requested on init stage and are kept acquired until the device is removed. Obviously SPI controller FIFO depth can't be changed. Due to all of that we can safely move the DMA Transmit and Receive data level registers initialization to the SPI controller DMA init stage (when the SPI controller is being probed) instead of doing it for each SPI transfer when dma_setup is called. This shall speed the DMA-based SPI transfer initialization up a bit, particularly if the APB bus is relatively slow. Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> Link: https://lore.kernel.org/r/20200920112322.24585-2-Sergey.Semin@baikalelectronics.ruSigned-off-by: Mark Brown <broonie@kernel.org>
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