[U-Boot] Raspberry Pi with driver model

[Simon Glass]

Hi Stephen,

On 24 November 2014 at 21:21, Stephen Warren <swarren at nvidia.com> wrote:
> On 11/24/2014 08:58 AM, Simon Glass wrote:
>> Hi Stephen,
>>
>> There was another thread where you reported a hang when booting
>> Raspberry Pi with driver model. It can be repeated by applying this
>> patch and trying to boot with syslinux.
>>
>> http://patchwork.ozlabs.org/patch/392180/
>>
>> When it hangs, the HDMI display displays lots of spaces, then lots of
>> dots, scrolling forever. The serial console displays nothing further.
>>
>> I narrowed the problem down to writing to address 0. So it is easy to
>> repeat with something like 'mw 0 0'.
>>
>> However I'm really not sure what is going on. Something with driver
>> model seems to make address 0 sensitive to writes. I can't see what
>> that might be, but I don't understand the platform very well. Do you
>> have any ideas?
>
> The problem seems to be that inside pl01x_serial_probe() (well, I assume
> all serial functions), dev_get_priv() returns 0, which ends up using
> address 0 as the UART address since that's the first field in struct
> pl01x_priv.
>
> I found this by amending pl01x_serial_probe() as follows, and dumping
> the data after boot:
>
> uint32_t *log = (uint32_t *)(128*1024*1024);
> uint32_t log_i = 1;
>
> static int pl01x_serial_probe(struct udevice *dev)
> {
>         struct pl01x_serial_platdata *plat = dev_get_platdata(dev);
>         struct pl01x_priv *priv = dev_get_priv(dev);
>
>         log[log_i++] = (uint32_t)dev;
>         log[log_i++] = (uint32_t)plat;
>         log[log_i++] = (uint32_t)priv;
>         log[0] = log_i;
>         priv->regs = (struct pl01x_regs *)plat->base;
>         priv->type = plat->type;
>         return pl01x_generic_serial_init(priv->regs, priv->type);
> }
>
> U-Boot> md.l 0x08000000
> 08000000: 00000007 07fffaf8 0003972c 00000000    ........,.......
> 08000010: 1db4e108 1df8372c 00000000 00000000    ....,7..........
>
> It seems a bit odd that pl01x_serial_probe() is called twice, but
> perhaps that's expected?

Thanks for finding that! It just needs this in the U_BOOT_DRIVER()
declaration in the serial driver:

.priv_auto_alloc_size = sizeof(struct pl01x_priv),

Then it all works. I'll update the series and resend. Thanks again.

Yes it will call the serial probe once before relocation, once after.

Regards,
Simon