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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 /include/linux/dmaengine.h
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 'include/linux/dmaengine.h')
-rw-r--r--include/linux/dmaengine.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 861be5cab1df..c8c3a7a93802 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -415,7 +415,9 @@ enum dma_residue_granularity {
* each type, the dma controller should set BIT(<TYPE>) and same
* should be checked by controller as well
* @max_burst: max burst capability per-transfer
- * @cmd_pause: true, if pause and thereby resume is supported
+ * @cmd_pause: true, if pause is supported (i.e. for reading residue or
+ * for resume later)
+ * @cmd_resume: true, if resume is supported
* @cmd_terminate: true, if terminate cmd is supported
* @residue_granularity: granularity of the reported transfer residue
* @descriptor_reuse: if a descriptor can be reused by client and
@@ -427,6 +429,7 @@ struct dma_slave_caps {
u32 directions;
u32 max_burst;
bool cmd_pause;
+ bool cmd_resume;
bool cmd_terminate;
enum dma_residue_granularity residue_granularity;
bool descriptor_reuse;