kernel_optimize_test/sound/soc/sunxi
Chen-Yu Tsai 730e2dd0cb ASoC: sun4i-codec: Increase DMA max burst to 8
According to the DMA engine API documentation, maxburst denotes the
largest possible size of a single transfer, so as not to overflow
destination FIFOs as explained in this excerpt from dmaengine.h

 * @src_maxburst: the maximum number of words (note: words, as in
 * units of the src_addr_width member, not bytes) that can be sent
 * in one burst to the device. Typically something like half the
 * FIFO depth on I/O peripherals so you don't overflow it. This
 * may or may not be applicable on memory sources.
 * @dst_maxburst: same as src_maxburst but for destination target
 * mutatis mutandis.

The TX FIFO is 64 samples deep for stereo, and the RX FIFO is 16
samples deep. So maxburst could be 32 and 8 for TX and RX respectively.

Unfortunately the sunxi DMA controller driver takes maxburst as
the requested burst size, rather than a limit, and returns an error
for unsupported values. The original value was 4, but some later
SoCs do not officially support this burst size.

This patch increases maxburst on the TX side to 8, which is supported
by all variants of the sunxi DMA controller.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2016-11-03 14:29:44 -06:00
..
Kconfig ASoC: sunxi: depend on ARCH_SUNXI 2016-08-24 10:41:15 +01:00
Makefile ASoC: sunxi: Add Allwinner A10 Digital Audio driver 2016-06-29 22:42:53 +01:00
sun4i-codec.c ASoC: sun4i-codec: Increase DMA max burst to 8 2016-11-03 14:29:44 -06:00
sun4i-i2s.c ASoC: sun4i-i2s: Implement capture support 2016-11-03 10:54:19 -06:00
sun4i-spdif.c ASoC: sunxi: compatibility for sun6i to SPDIF 2016-08-12 12:00:34 +01:00