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authorMarek Szyprowski <m.szyprowski@samsung.com>2018-07-02 16:08:10 +0300
committerVinod Koul <vkoul@kernel.org>2018-07-09 20:29:04 +0300
commitd8095f94e19581057bcad35b8a725aa739e77595 (patch)
tree5926a5a47750d50d9498b8126ccd5db0735856f5 /drivers/dma/dmaengine.c
parentce397d215ccd07b8ae3f71db689aedb85d56ab40 (diff)
downloadlinux-d8095f94e19581057bcad35b8a725aa739e77595.tar.xz
dmaengine: add support for reporting pause and resume separately
'cmd_pause' DMA channel capability means that respective DMA engine supports both pausing and resuming given DMA channel. However, in some cases it is important to know if DMA channel can be paused without the need to resume it. This is a typical requirement for proper residue reading on transfer timeout in UART drivers. There are also some DMA engines with limited hardware, which doesn't really support resuming. Reporting pause and resume capabilities separately allows UART drivers to properly check for the really required capabilities and operate in DMA mode also in systems with limited DMA hardware. On the other hand drivers, which rely on full channel suspend/resume support, should now check for both 'pause' and 'resume' features. Existing clients of dma_get_slave_caps() have been checked and the only driver which rely on proper channel resuming is soc-generic-dmaengine-pcm driver, which has been updated to check the newly added capability. Existing 'cmd_pause' now only indicates that DMA engine support pausing given DMA channel. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Acked-by: Mark Brown <broonie@kernel.org> Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma/dmaengine.c')
-rw-r--r--drivers/dma/dmaengine.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 08ba8473a284..84ac38dbdb65 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -500,12 +500,8 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps)
caps->max_burst = device->max_burst;
caps->residue_granularity = device->residue_granularity;
caps->descriptor_reuse = device->descriptor_reuse;
-
- /*
- * Some devices implement only pause (e.g. to get residuum) but no
- * resume. However cmd_pause is advertised as pause AND resume.
- */
- caps->cmd_pause = !!(device->device_pause && device->device_resume);
+ caps->cmd_pause = !!device->device_pause;
+ caps->cmd_resume = !!device->device_resume;
caps->cmd_terminate = !!device->device_terminate_all;
return 0;