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

On Wed, 2014-08-27 at 00:46 -0500, Mehresh Ramneek-B31383 wrote:

quoted

-----Original Message-----
From: Wood Scott-B07421
Sent: Wednesday, August 27, 2014 4:23 AM
To: Mehresh Ramneek-B31383
Cc: Badola Nikhil-B46172; 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 Fri, 2014-08-22 at 00:05 -0500, Mehresh Ramneek-B31383 wrote:

quoted

-----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

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quoted

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+   "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.

we could have done...but we have a requirement to write version specific code...
for instance, usb controller init sequence has changes from version 2.5 onwards...
then there are version specific errata fixe(s) also. Hence we decided to go for
compatible string containing hw ip version (major no.) so that our workaround/code is
consistent with hw ip version(s) published in errata(s)

I wasn't saying ignore version differences.  I was suggesting that we
make a special case out of older versions where the version register is
different/broken.

-Scott