dmaengine Archive on lore.kernel.org
 help / color / Atom feed
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
To: <vinod.koul@intel.com>, <robh+dt@kernel.org>
Cc: <dmaengine@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<dan.j.williams@intel.com>, <devicetree@vger.kernel.org>
Subject: [RFC 1/3] dt-bindings: dma: Add documentation for DMA domains
Date: Fri, 6 Sep 2019 17:17:15 +0300
Message-ID: <20190906141717.23859-2-peter.ujfalusi@ti.com> (raw)
In-Reply-To: <20190906141717.23859-1-peter.ujfalusi@ti.com>

On systems where multiple DMA controllers available, none Slave (for example
memcpy operation) users can not be described in DT as there is no device
involved from the DMA controller's point of view, DMA binding is not usable.
However in these systems still a peripheral might need to be serviced by or
it is better to serviced by specific DMA controller.
When a memcpy is used to/from a memory mapped region for example a DMA in the
same domain can perform better.
For generic software modules doing mem 2 mem operations it also matter that
they will get a channel from a controller which is faster in DDR to DDR mode
rather then from the first controller happen to be loaded.

This property is inherited, so it may be specified in a device node or in any
of its parent nodes.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
 .../devicetree/bindings/dma/dma-domain.yaml   | 59 +++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/dma-domain.yaml

diff --git a/Documentation/devicetree/bindings/dma/dma-domain.yaml b/Documentation/devicetree/bindings/dma/dma-domain.yaml
new file mode 100644
index 000000000000..c2f182f30081
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/dma-domain.yaml
@@ -0,0 +1,59 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/dma-controller.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: DMA Domain Controller Definition
+
+maintainers:
+  - Vinod Koul <vkoul@kernel.org>
+
+allOf:
+  - $ref: "dma-controller.yaml#"
+
+description:
+  On systems where multiple DMA controllers available, none Slave (for example
+  memcpy operation) users can not be described in DT as there is no device
+  involved from the DMA controller's point of view, DMA binding is not usable.
+  However in these systems still a peripheral might need to be serviced by or
+  it is better to serviced by specific DMA controller.
+  When a memcpy is used to/from a memory mapped region for example a DMA in the
+  same domain can perform better.
+  For generic software modules doing mem 2 mem operations it also matter that
+  they will get a channel from a controller which is faster in DDR to DDR mode
+  rather then from the first controller happen to be loaded.
+
+  This property is inherited, so it may be specified in a device node or in any
+  of its parent nodes.
+
+properties:
+  $dma-domain-controller:
+    $ref: /schemas/types.yaml#definitions/phandle
+    description:
+      phande to the DMA controller node which should be used for the device or
+      domain.
+
+examples:
+  - |
+    / {
+        model = "Texas Instruments K3 AM654 SoC";
+        compatible = "ti,am654";
+        interrupt-parent = <&gic500>;
+        /* For modules without device, DDR to DDR is faster on main UDMAP */
+        dma-domain-controller = <&main_udmap>;
+        #address-cells = <2>;
+        #size-cells = <2>;
+        ...
+    };
+
+    &cbass_main {
+        /* For modules within MAIN domain, use main UDMAP */
+        dma-domain-controller = <&main_udmap>;
+    };
+
+    &cbass_mcu {
+        /* For modules within MCU domain, use mcu UDMAP */
+        dma-domain-controller = <&mcu_udmap>;
+    };
+...
-- 
Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki


  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 14:17 [RFC 0/3] dmaengine: Support for DMA domain controllers Peter Ujfalusi
2019-09-06 14:17 ` Peter Ujfalusi [this message]
2019-09-06 14:17 ` [RFC 2/3] dmaengine: of_dma: Function to look up the DMA domain of a client Peter Ujfalusi
2019-09-06 14:17 ` [RFC 3/3] dmaengine: Support for requesting channels preferring DMA domain controller Peter Ujfalusi
2019-09-06 14:18 [RFC 0/3] dmaengine: Support for DMA domain controllers Peter Ujfalusi
2019-09-06 14:18 ` [RFC 1/3] dt-bindings: dma: Add documentation for DMA domains Peter Ujfalusi
2019-09-08  7:47   ` Peter Ujfalusi
2019-09-08 12:10     ` Vinod Koul
2019-09-09  6:30       ` Peter Ujfalusi
2019-09-12 17:03         ` Vinod Koul
2019-09-13  7:21           ` Peter Ujfalusi
2019-09-13 10:36             ` Vinod Koul
2019-09-13 12:19               ` Peter Ujfalusi
2019-09-13 13:33                 ` Vinod Koul
2019-09-08 12:06   ` Vinod Koul
2019-09-09  6:00     ` Peter Ujfalusi

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190906141717.23859-2-peter.ujfalusi@ti.com \
    --to=peter.ujfalusi@ti.com \
    --cc=dan.j.williams@intel.com \
    --cc=devicetree@vger.kernel.org \
    --cc=dmaengine@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=robh+dt@kernel.org \
    --cc=vinod.koul@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

dmaengine Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dmaengine/0 dmaengine/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dmaengine dmaengine/ https://lore.kernel.org/dmaengine \
		dmaengine@vger.kernel.org dmaengine@archiver.kernel.org
	public-inbox-index dmaengine

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.dmaengine


AGPL code for this site: git clone https://public-inbox.org/ public-inbox