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linux/drivers/dma
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Lukas Wunner bf75703d09
dmaengine: bcm2835: Avoid accessing memory when copying zeroes 
The BCM2835 DMA controller is capable of synthesizing zeroes instead of
copying them from a source address. The feature is enabled by setting
the SRC_IGNORE bit in the Transfer Information field of a Control Block:

"Do not perform source reads.
 In addition, destination writes will zero all the write strobes.
 This is used for fast cache fill operations."
https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf

The feature is only available on 8 of the 16 channels. The others are
so-called "lite" channels with a limited feature set and performance.

Enable the feature if a cyclic transaction copies from the zero page.
This reduces traffic on the memory bus.

A forthcoming use case is the BCM2835 SPI driver, which will cyclically
copy from the zero page to the TX FIFO. The idea to use SRC_IGNORE was
taken from an ancient GitHub conversation between Martin and Noralf:
https://github.com/msperl/spi-bcm2835/issues/13#issuecomment-98180451

Tested-by: Nuno Sá <nuno.sa@analog.com>
Tested-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Vinod Koul <vkoul@kernel.org>
Acked-by: Stefan Wahren <wahrenst@gmx.net>
Acked-by: Martin Sperl <kernel@martin.sperl.org>
Cc: Florian Kauer <florian.kauer@koalo.de>
Link: https://lore.kernel.org/r/b2286c904408745192e4beb3de3c88f73e4a7210.1568187525.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
2019-09-11 15:56:46 +01:00
..
bestcomm treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
dw dmaengine: dw: Enable iDMA 32-bit on Intel Elkhart Lake 2019-06-25 10:03:33 +05:30
dw-axi-dmac dmaengine fixes for v5.2-rc4 2019-06-08 12:46:31 -07:00
dw-edma dmaengine: dw-edma: fix semicolon.cocci warnings 2019-06-25 09:59:36 +05:30
hsu dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
ioat treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 291 2019-06-05 17:36:38 +02:00
ipu treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mediatek dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
ppc4xx treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 7 2019-05-21 11:28:40 +02:00
qcom dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
sh dmaengine: rcar-dmac: Reject zero-length slave DMA requests 2019-06-25 10:08:22 +05:30
ti treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
xilinx dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
acpi-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
altera-msgdma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
amba-pl08x.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
at_hdmac_regs.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
at_hdmac.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
at_xdmac.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
bcm2835-dma.c dmaengine: bcm2835: Avoid accessing memory when copying zeroes 2019-09-11 15:56:46 +01:00
bcm-sba-raid.c dmaengine: bcm-sba-raid: no need to check return value of debugfs_create functions 2019-06-14 11:14:58 +05:30
coh901318_lli.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
coh901318.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
coh901318.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
dma-axi-dmac.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
dma-jz4740.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
dma-jz4780.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
dmaengine.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
dmaengine.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dmatest.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
ep93xx_dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
fsl_raid.c dmaengine: fsl_raid: make of_device_ids const. 2017-06-29 09:25:28 +05:30
fsl_raid.h dmaengine: Driver support for FSL RaidEngine device. 2015-04-02 16:10:27 +05:30
fsl-edma-common.c dmaengine: Revert "dmaengine: fsl-edma: add i.mx7ulp edma2 version support" 2019-07-08 09:44:45 +05:30
fsl-edma-common.h dmaengine: Revert "dmaengine: fsl-edma: add i.mx7ulp edma2 version support" 2019-07-08 09:44:45 +05:30
fsl-edma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
fsl-qdma.c dmaengine: fsl-qdma: Continue to clear register on error 2019-06-04 17:35:05 +05:30
fsldma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 40 2019-05-24 17:27:12 +02:00
fsldma.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 40 2019-05-24 17:27:12 +02:00
idma64.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
idma64.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
img-mdc-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 422 2019-06-05 17:37:15 +02:00
imx-dma.c dmaengine updates for v5.1-rc1 2019-03-14 09:11:54 -07:00
imx-sdma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
iop-adma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288 2019-06-05 17:36:37 +02:00
k3dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Kconfig dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
lpc18xx-dmamux.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Makefile dmaengine: Add Synopsys eDMA IP core driver 2019-06-10 13:10:39 +05:30
mcf-edma.c dmaengine: fsl-edma: add drvdata for fsl-edma 2019-07-03 13:28:22 +05:30
mic_x100_dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
mic_x100_dma.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 290 2019-06-05 17:36:38 +02:00
mmp_pdma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
mmp_tdma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
moxart-dma.c treewide: Use struct_size() for kmalloc()-family 2018-06-06 11:15:43 -07:00
mpc512x_dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 7 2019-05-21 11:28:40 +02:00
mv_xor_v2.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 24 2019-05-21 11:52:39 +02:00
mv_xor.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288 2019-06-05 17:36:37 +02:00
mv_xor.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 288 2019-06-05 17:36:37 +02:00
mxs-dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
nbpfaxi.c dmaengine: nbpfaxi: Use dev_get_drvdata() 2019-04-29 10:47:15 +05:30
of-dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
owl-dma.c dmaengine: owl: Fix warnings generated during build 2018-10-15 22:39:16 +05:30
pch_dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
pl330.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
pxa_dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
s3c24xx-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sa11x0-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
sirf-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 4 2019-05-21 11:28:40 +02:00
sprd-dma.c dmaengine: sprd: Add interrupt support for 2-stage transfer 2019-05-21 19:23:54 +05:30
st_fdma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
st_fdma.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ste_dma40_ll.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
ste_dma40_ll.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
ste_dma40.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 194 2019-05-30 11:29:22 -07:00
stm32-dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
stm32-dmamux.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
stm32-mdma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
sun4i-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sun6i-dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
tegra20-apb-dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
tegra210-adma.c dmaengine fixes for v5.2-rc4 2019-06-08 12:46:31 -07:00
timb_dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 174 2019-05-30 11:26:41 -07:00
TODO dmaengine: dw: don't perform DMA when dmaengine_submit is called 2014-07-15 22:14:30 +05:30
txx9dmac.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
txx9dmac.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
uniphier-mdmac.c dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver 2018-11-24 19:42:59 +05:30
virt-dma.c dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
virt-dma.h dmaengine updates for v5.3-rc1 2019-07-17 09:55:43 -07:00
xgene-dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 13 2019-05-21 11:28:45 +02:00
zx_dma.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00