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

[Bin Meng]

Hi Simon,

On Thu, Aug 6, 2015 at 10:36 AM, Simon Glass <sjg at chromium.org> wrote:
> Hi Bin,
>
> On 5 August 2015 at 20:22, Bin Meng <bmeng.cn at gmail.com> wrote:
>> Hi Simon,
>>
>> On Wed, Aug 5, 2015 at 10:40 PM, Simon Glass <sjg at chromium.org> wrote:
>>> 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.
>>
>> So far I don't see any config r/w routines can trigger the enumeration.
>>
>>>
>>> In general we should try to make use of automatic probing - it was
>>> supposed to be a key feature of driver model.
>>>
>>
>> Yep I know this is supposed to be done this way. I am not sure how it
>> looks like on other domain, but at least it is now broken for dm pci.
>> In order to get the enumeration process automatically triggered, we
>> need make sure all public pci apis will end up triggering the
>> configuration.
>
> Provided that we always call uclass_get_device() or any of those
> *_get_* functions then the bus will be probed and thus enumerated.
>

Yes.

> The problem is that we have these sideways functions to accessing PCI
> on x86. Once we get rid of those then we should be OK. Everything
> should use a struct udevice.
>

Do you plan to fix this or is there already a patch that I missed?

Regards,
Bin