[U-Boot] [PATCH 4/5] x86: Explicitly trigger pci bus configuration with driver model

[Simon Glass]

Hi Bin,

On 2 August 2015 at 19:54, Bin Meng <bmeng.cn at gmail.com> wrote:
> Hi Simon,
>
> On Mon, Aug 3, 2015 at 6:31 AM, Simon Glass <sjg at chromium.org> wrote:
>> Hi Bin,
>>
>> On 27 July 2015 at 01:33, Bin Meng <bmeng.cn at gmail.com> wrote:
>>> With driver model, probing pci bus is all done on a lazy basis,
>>> as needed. On x86, pci bus is the fundamental device that needs
>>> to work before any other peripherals. In order to have a working
>>> pci before any other pci devices can be initialized, we need
>>> explicitly trigger the pci bus configuration.
>>>
>>> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
>>> ---
>>>
>>>  common/board_r.c | 16 ++++++++++++++++
>>>  1 file changed, 16 insertions(+)
>>>
>>> diff --git a/common/board_r.c b/common/board_r.c
>>> index bf6c725..4263e47 100644
>>> --- a/common/board_r.c
>>> +++ b/common/board_r.c
>>> @@ -233,6 +233,22 @@ static int initr_pci(void)
>>>  {
>>>  #ifndef CONFIG_DM_PCI
>>>         pci_init();
>>> +#else
>>> +#ifdef CONFIG_X86
>>> +       /*
>>> +        * With driver model, probing pci bus is all done on a lazy basis,
>>> +        * as needed. On x86, pci bus is the fundamental device that needs
>>> +        * to work before any other peripherals. In order to have a working
>>> +        * pci before any other pci devices can be initialized, we need
>>> +        * explicitly trigger the pci bus configuration.
>>> +        */
>>> +       struct udevice *dev;
>>> +       int ret;
>>> +
>>> +       ret = uclass_first_device(UCLASS_PCI, &dev);
>>> +       if (ret)
>>> +               return ret;
>>
>> Won't this happen anyway when you first access a PCI device?
>>
>
> Unfortunately no. The pci bus configuration will not be triggered when
> calling pci config read/write.
>
> [snip]

We should be able to use the dm_pci_config..() functions and by just
getting hold of the bus device it should probe the bus before doing
any config. Then it would be auto-triggered.

In general we should try to make use of automatic probing - it was
supposed to be a key feature of driver model.

Regards,
Simon