Re: [PATCH] Documentation: dts: fsl-usb: Document USB node compatible string for IP version

On Fri, 2014-08-22 at 00:05 -0500, Mehresh Ramneek-B31383 wrote:

-----Original Message-----
From: Badola Nikhil-B46172 
Sent: Friday, August 22, 2014 10:18 AM
To: Wood Scott-B07421
Cc: linuxppc-dev@lists.ozlabs.org; devicetree@vger.kernel.org; Mehresh Ramneek-B31383
Subject: RE: [PATCH] Documentation: dts: fsl-usb: Document USB node compatible string for IP version

Adding Ramneek

quoted

-----Original Message-----
From: Wood Scott-B07421
Sent: Friday, August 22, 2014 3:53 AM
To: Badola Nikhil-B46172
Cc: linuxppc-dev@lists.ozlabs.org; devicetree@vger.kernel.org
Subject: Re: [PATCH] Documentation: dts: fsl-usb: Document USB node 
compatible string for IP version

On Thu, 2014-08-21 at 14:48 +0530, Nikhil Badola wrote:

quoted

Document compatible string containing IP version in USB device tree 
node

Signed-off-by: Nikhil Badola <redacted>
---
 Documentation/devicetree/bindings/usb/fsl-usb.txt | 13 
++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

Please CC devicetree@vger.kernel.org on all device tree patches (in 
addition to linuxppc-dev).

quoted

diff --git a/Documentation/devicetree/bindings/usb/fsl-usb.txt

b/Documentation/devicetree/bindings/usb/fsl-usb.txt
index 4779c02..5a3a0a8 100644

--- a/Documentation/devicetree/bindings/usb/fsl-usb.txt
+++ b/Documentation/devicetree/bindings/usb/fsl-usb.txt

@@ -10,7 +10,10 @@ Required properties :
    controllers, or "fsl-usb2-dr" for dual role USB controllers
    or "fsl,mpc5121-usb2-dr" for dual role USB controllers of MPC5121.
    Wherever applicable, the IP version of the USB controller should
-   also be mentioned (for eg. fsl-usb2-dr-v2.2 for bsc9132).
+   also be mentioned in another string.
+   For multi port host USB controller with IP version <IP_Ver>, it should be
+   "fsl-usb2-mph-<IP_Ver>". For dual role USB controller with IP version
+   <IP_Ver>, it should be "fsl-usb2-dr-<IP_Ver>".

It was documented before -- this is just making it more explicit, right?

FWIW, the version number can be read out of a USB register, so I'd 
rather remove the suggestion to specify the version number and replace 
it with a reference to the ID register.

we have following two issues -
(a) our USBIP version register doesn't have consistent "version field size" over 
multiple version(s). This is why we couldn't use it for reading version info across
various IP versions
(b) this register is not exposed in all SoC RMs (probably because of above reason)

:-(

If this is just a problem with older chips, we could have a new
compatible name that designates the family of USB block versions with a
sane version register.

quoted

quoted

@@ -55,9 +58,9 @@ Example multi port host USB controller device node :
 		port1;
 	};

-Example dual role USB controller device node :
+Example dual role USB controller version 2.5 device node :
 	usb@23000 {
-		compatible = "fsl-usb2-dr";
+		compatible = "fsl-usb2-dr-v2.5", "fsl-usb2-dr";
 		reg = <23000 1000>;
 		#address-cells = <1>;
 		#size-cells = <0>;

This example doesn't correspond to any device tree I see.  Even after 
your next patch that sets t2080's USB to v2.5, the addresses are different.

I reckon that the example emphasizes on showing how IP version information is
to be stored in "compatible string". Is it necessary to make sure that we should 
always site actual values already used?

The more realistic the examples are, the better.

-Scott