[U-Boot] [PATCH] mx6: Fix the reading of CPU revision

[Dirk Behme <dirk.behme@de.bosch.com>]

On 26.03.2013 18:04, Fabio Estevam wrote:
> Hi Dirk,
> 
> On Tue, Mar 26, 2013 at 12:43 PM, Dirk Behme <dirk.behme@de.bosch.com> wrote:
>> Hi Fabio,
>>
>>
>> On 26.03.2013 13:54, Fabio Estevam wrote:
>>> Currently when booting a mx6 solo processor get_cpu_rev() returns 0x62xxx,
>>> which
>>> is an invalid mx6 CPU revision.
>>
>> Do you have somewhere a list of valid CPU revisions? From two points of
>> view:
>>
>> a) the i.MX6 hardware spec
>>
>> b) the VPU library
> 
> Sorry, I don't. I am basing the CPU revision numbers from FSL U-boot:
> http://git.freescale.com/git/cgit.cgi/imx/uboot-imx.git/tree/board/freescale/common/fsl_sys_rev.c?h=imx_v2009.08_3.0.0
> 
> Adding Jason, in case he could clarify it.
> 
>> You remove Troy's code here introduced with
>>
>> http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commitdiff;h=20332a066aff98f39419495821e14edd10b2a3f8
>>
>> Troy's detection you remove here intentionally distinguishes between
>> DualLite and Solo. You now re-introduce a common DL_S, again.
>>
>> Additionally, you completely seem to drop checking for scu->config. I've
>> already seen some (broken?) i.MX6Solo where this check was essential.
>>
>> I can't talk about the "problems when trying to use VPU library in the
>> kernel" (btw, which problems?) and the invalid 0x62xxx, but we used Troy's
>> version of the detection successfully.
> 
> Passing 0x62xxx as cpu_rev on a mx6solo caused the VPU issues described here:
> https://community.freescale.com/thread/305396
> 
> Which cpu_rev value is returned with your mx6solo? Are you able to use VPU lib?

I'll check this.

Rethinking about the issue here, my recent understanding is:

a) We have a VPU library which only understands 0x63 (Quad) and 0x61 
(DualLite/Solo)

b) We have Troy's existing get_cpu_rev() [1] which seems to correctly 
decode the CPU revision (at least this is my impression from testing ;) 
). But reports 0x62 for the Solo which then isn't understood by the VPU 
library (to be checked).

I wonder if we could find a way to combine both parts without breaking 
the other? I.e. using Troy's get_cpu_rev() to correctly report the CPU 
revision (in U-Boot), but let the VPU library get the revision it 
understands?

Best regards

Dirk

[1] 
http://git.denx.de/cgi-bin/gitweb.cgi?p=u-boot.git;a=commitdiff;h=20332a066aff98f39419495821e14edd10b2a3f8