RE: [PATCH 1/2] powerpc/qman: Change fsl,qman-channel-id to cell-index

[Roy Pledge <roy.pledge-KZfg59tc24xl57MIdRCFDg@public.gmane.org>]

Sorry for the slow reply.

I don't believe this is correct - let me explain the rational why we had two properties in the QMan portal to begin with.

The two properties in question are cell-index and fsl,qman-channel-id.

The cell-index property is used in u-boot as an index for the software portal ID when adding the fsl,liodn from the U-boot table into the device tree.

The  fsl,qman-channel-id property is used in Linux and corresponds to a hardware value that indicates which channel is dedicated to the software portal.

While I'm not aware of a current SoC where the channel ID for a software portal does not match the index (i.e. SWP 0 uses channel 0, etc.) it is possible that future SoCs could stray from this model, there is no reason for portal index to equal channel ID at all times.

Roy


-----Original Message-----
From: Linuxppc-dev [mailto:linuxppc-dev-bounces+roy.pledge=freescale.com@lists.ozlabs.org] On Behalf Of Scott Wood
Sent: Friday, April 17, 2015 6:53 PM
To: linuxppc-dev@lists.ozlabs.org
Cc: Wood Scott-B07421; devicetree@vger.kernel.org; Bucur Madalin-Cristian-B32716
Subject: [PATCH 1/2] powerpc/qman: Change fsl,qman-channel-id to cell-index

It turns out that existing U-Boots will dereference NULL pointers if the device tree does not have cell-index in the portal nodes.

No patch has yet been merged adding device tree nodes for this binding (except a dtsi that has not yet been referenced), nor has any driver yet been merged making use of the binding, so it's not too late to change the binding in order to keep compatibility with existing U-Boots.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Cc: Madalin-Cristian Bucur <madalin.bucur@freescale.com>
---
 Documentation/devicetree/bindings/soc/fsl/qman-portals.txt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/soc/fsl/qman-portals.txt b/Documentation/devicetree/bindings/soc/fsl/qman-portals.txt
index 48c4dae..47e46cc 100644
--- a/Documentation/devicetree/bindings/soc/fsl/qman-portals.txt
+++ b/Documentation/devicetree/bindings/soc/fsl/qman-portals.txt
@@ -47,7 +47,7 @@ PROPERTIES
 
 	For additional details about the PAMU/LIODN binding(s) see pamu.txt
 
-- fsl,qman-channel-id
+- cell-index
 	Usage:		Required
 	Value type:	<u32>
 	Definition:	The hardware index of the channel. This can also be
@@ -136,7 +136,7 @@ The example below shows a (P4080) QMan portals container/bus node with two porta
 			reg = <0x4000 0x4000>, <0x101000 0x1000>;
 			interrupts = <106 2 0 0>;
 			fsl,liodn = <3 4>;
-			fsl,qman-channel-id = <1>;
+			cell-index = <1>;
 
 			fman0 {
 				fsl,liodn = <0x22>;
--
2.1.0

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