[U-Boot] ARM CONFIG_OF_CONTROL status

[Simon Glass]

Hi Michal,

On Wed, Jun 27, 2012 at 7:35 AM, Michal Simek <monstr at monstr.eu> wrote:

> Hi Simon,
>
>
> On 06/27/2012 03:58 PM, Simon Glass wrote:
>
>> Hi,
>>
>>
>> On Wed, Jun 27, 2012 at 2:29 AM, Michal Simek <monstr at monstr.eu <mailto:
>> monstr at monstr.eu>> wrote:
>>
>>    Hi,
>>
>>    can you please update me about current state of CONFIG_OF_CONTROL for
>> ARM?
>>    Are there any other archs/boards which will use this option?
>>
>>    Or any other git repo out of mainline u-boot?
>>
>>
>> Exynos is in progress - development is happening in the Chromium tree and
>> being upstreamed in chunks (although no fdt patches have been sent yet).
>>
>
> ok.
>
>
>
>>
>>    Has someone tried to look for devices based on compatible property?
>>    I see that in usb driver it is based on aliases which is not the best
>> solution.
>>
>>
>> U-Boot doesn't yet have a device model which would allow this in the
>> general case. For now, drivers look for their own compatible nodes. This
>> works well enough until we have a device model.
>>
>> There are other limitations also - for example USB supports only a single
>> controller type working at one time (a restriction we may need to look at
>> to support USB2 and USB3 together). So even if two USB drivers decided that
>> they both found compatible nodes, only one of them could operate. So for
>> now aliases provide just an ordering, nothing else.
>>
>
>
> I have looked at the code and did some tests on Microblaze.
>
> Firstly I have tried to change emaclite ethernet initialization and I
> ended with this code fragment which could be
> broadly used by other drivers.
>
>        int offset = 0;
>        do {
>                offset = fdt_node_offset_by_compatible(**gd->fdt_blob,
> offset, "xlnx,xps-ethernetlite-1.00.a" );
>

You could check if offset < 0 here, or !fdtdec_get_is_enabled(gd->fdt_blob,
offset)


>                u32 rxpp = fdtdec_get_int(gd->fdt_blob, offset,
> "xlnx,rx-ping-pong", 0);
>                u32 txpp = fdtdec_get_int(gd->fdt_blob, offset,
> "xlnx,tx-ping-pong", 0);
>                u32 reg = fdtdec_get_int(gd->fdt_blob, offset, "reg", 0);
>

Maybe fdtdec_get_addr()


>                if (reg)
>                        ret |= xilinx_emaclite_initialize(**bis, reg,
> txpp, rxpp);
>        } while (offset != -1);
>
> What do you think? This code is in platform file.
>

Seems reasonable to me.

>
> Also I have tested code around aliases which parse DTS aliases list for
> console initialization
> and I have also get it work for !CONSOLE_SERIAL_MULTI case.
>

Great - I did send a patch to the list for fdt serial, but haven't really
got back to it.

>
> What was the reason to use compat_names table in fdtdec.c file?


Just so there is a simple register of everything that uses fdt in U-Boot -
the enum is used by driver code. If we end up with a lot of support then we
might reconsider one day

Regards,
Simon

>
>
> Thanks,
> Michal
>
>
> --
> Michal Simek, Ing. (M.Eng)
> w: www.monstr.eu p: +42-0-721842854
> Maintainer of Linux kernel 2.6 Microblaze Linux -
> http://www.monstr.eu/fdt/
> Microblaze U-BOOT custodian
>