Lukas Wunner <lukas@xxxxxxxxx> writes: > Without this, the driver for the BCM2835 SPI controller uses interrupt > mode instead of DMA mode, incurring a significant performance penalty. > The Foundation's device tree has had these attributes for years, but for > some reason they were never upstreamed. > > They were originally contributed by Noralf Trønnes and Martin Sperl: > https://github.com/raspberrypi/linux/commit/25f3e064afc8 > https://github.com/raspberrypi/linux/commit/e0edb52b47e6 > > The DREQ numbers 6 and 7 are documented in section 4.2.1.3 of: > https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf > > Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> > Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
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