2021-04-09 17:58:54

by Radhey Shyam Pandey

Subject: [RFC v2 PATCH 2/7] dt-bindings: dmaengine: xilinx_dma: Add xlnx,irq-delay property

Add an optional AXI DMA property 'xlnx,irq-delay'. It specifies interrupt
timeout value and causes the DMA engine to generate an interrupt after the
delay time period has expired. Timer begins counting at the end of a packet
and resets with receipt of a new packet or a timeout event occurs.

This property is useful when AXI DMA is connected to the streaming IP i.e
axiethernet where inter packet latency is critical while still taking the
benefit of interrupt coalescing.

Signed-off-by: Radhey Shyam Pandey <[email protected]>
---
Changes for v2:
- New patch. Introduce xlnx,irq-delay property for low latency usecases
---
Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
index f5f23a4a4467..96009ced7b29 100644
--- a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
+++ b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
@@ -50,7 +50,9 @@ Optional properties for AXI DMA and MCDMA:
is missing or invalid then the default value 23 is used. This is the
maximum value that is supported by all IP versions.
- xlnx,axistream-connected: Tells whether DMA is connected to AXI stream IP.
-
+- xlnx,irq-delay: Tells the interrupt delay timeout value. Valid range is from
+ 0-255. Setting this value to zero disables the delay timer interrupt.
+ 1 timeout interval = 125 * clock period of SG clock.
Optional properties for VDMA:
- xlnx,flush-fsync: Tells which channel to Flush on Frame sync.
It takes following values:
--
2.7.4

2021-04-13 06:29:10

by Rob Herring (Arm)

Subject: Re: [RFC v2 PATCH 2/7] dt-bindings: dmaengine: xilinx_dma: Add xlnx,irq-delay property

On Fri, 09 Apr 2021 23:26:00 +0530, Radhey Shyam Pandey wrote:
> Add an optional AXI DMA property 'xlnx,irq-delay'. It specifies interrupt
> timeout value and causes the DMA engine to generate an interrupt after the
> delay time period has expired. Timer begins counting at the end of a packet
> and resets with receipt of a new packet or a timeout event occurs.
>
> This property is useful when AXI DMA is connected to the streaming IP i.e
> axiethernet where inter packet latency is critical while still taking the
> benefit of interrupt coalescing.
>
> Signed-off-by: Radhey Shyam Pandey <[email protected]>
> ---
> Changes for v2:
> - New patch. Introduce xlnx,irq-delay property for low latency usecases
> ---
> Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>

Acked-by: Rob Herring <[email protected]>