[PATCH] dmadev: clarify visibility of completed jobs

[PATCH] dmadev: clarify visibility of completed jobs

[Bruce Richardson]

Clarify that once an operation has completed, the output of that
operation is visible to all cores.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---

This follows on from the discussion on-list[1]. Owing to the lack
of replies stating that hardware doesn't guarantee this property, I'm
taking the optimistic view and assuming that this is generally supported
by the DMA drivers. If not, I can do a different patch for some
capability flags to indicate the presence or not of this visibility
guarantee.

[1] https://lore.kernel.org/all/YkwxFZUqOfnL9cJC@bricha3-MOBL.ger.corp.intel.com/
---
 lib/dmadev/rte_dmadev.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/dmadev/rte_dmadev.h b/lib/dmadev/rte_dmadev.h
index ad9e7a0975..a7081e633c 100644
--- a/lib/dmadev/rte_dmadev.h
+++ b/lib/dmadev/rte_dmadev.h
@@ -1001,6 +1001,8 @@ rte_dma_submit(int16_t dev_id, uint16_t vchan)
  * @b EXPERIMENTAL: this API may change without prior notice.
  *
  * Return the number of operations that have been successfully completed.
+ * Once an operation has been reported as completed, the results of that
+ * operation will be visible to all cores on the system.
  *
  * @param dev_id
  *   The identifier of the device.
@@ -1058,6 +1060,8 @@ rte_dma_completed(int16_t dev_id, uint16_t vchan, const uint16_t nb_cpls,
  *
  * Return the number of operations that have been completed, and the operations
  * result may succeed or fail.
+ * Once an operation has been reported as completed successfully, the results of that
+ * operation will be visible to all cores on the system.
  *
  * @param dev_id
  *   The identifier of the device.
-- 
2.34.1

RE: [PATCH] dmadev: clarify visibility of completed jobs

[Morten Brørup]

> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Thursday, 12 May 2022 17.11
> 
> Clarify that once an operation has completed, the output of that
> operation is visible to all cores.
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---

Since I can't confirm that all hardware guarantees this property, a Review sign-off would be inappropriate.

Acked-by: Morten Brørup <mb@smartsharesystems.com>

Re: [PATCH] dmadev: clarify visibility of completed jobs

[Thomas Monjalon]

12/05/2022 18:18, Morten Brørup:
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > Sent: Thursday, 12 May 2022 17.11
> > 
> > Clarify that once an operation has completed, the output of that
> > operation is visible to all cores.
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > ---
> 
> Since I can't confirm that all hardware guarantees this property, a Review sign-off would be inappropriate.
> 
> Acked-by: Morten Brørup <mb@smartsharesystems.com>

Applied, thanks.