[U-Boot] [PATCH V2 1/2] pci: Support parsing PCI controller DT subnodes

[Marek Vasut]

On 09/19/2018 11:26 AM, Bin Meng wrote:
> Hi Marek,
> 
> On Wed, Sep 19, 2018 at 4:21 PM Marek Vasut <marek.vasut at gmail.com> wrote:
>>
>> On 09/18/2018 03:52 PM, Simon Glass wrote:
>>> Hi Marek,
>>>
>>> On 18 September 2018 at 13:36, Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>
>>>> On 09/14/2018 06:41 AM, Simon Glass wrote:
>>>>> Hi Marek,
>>>>>
>>>>> On 10 September 2018 at 01:38, Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>>>
>>>>>> On 09/02/2018 03:07 AM, Simon Glass wrote:
>>>>>>> Hi Marek,
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>>> On 1 September 2018 at 16:45, Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>>>>>
>>>>>>>> On 09/01/2018 11:50 PM, Simon Glass wrote:
>>>>>>>>> Hi Marek,
>>>>>>>>>
>>>>>>>>> On 30 August 2018 at 07:42, Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>>>>>>> On 08/30/2018 03:32 PM, Bin Meng wrote:
>>>>>>>>>>> Hi Marek,
>>>>>>>>>>>
>>>>>>>>>>> On Thu, Aug 30, 2018 at 1:07 AM Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> On 08/29/2018 05:15 PM, Bin Meng wrote:
>>>>>>>>>>>>> +Simon
>>>>>>>>>>>>>
>>>>>>>>>>>>> Hi Marek,
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Wed, Aug 29, 2018 at 10:22 PM Marek Vasut <marek.vasut at gmail.com> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 08/24/2018 08:27 PM, Marek Vasut wrote:
>>>>>>>>>>>>>>> The PCI controller can have DT subnodes describing extra properties
>>>>>>>>>>>>>>> of particular PCI devices, ie. a PHY attached to an EHCI controller
>>>>>>>>>>>>>>> on a PCI bus. This patch parses those DT subnodes and assigns a node
>>>>>>>>>>>>>>> to the PCI device instance, so that the driver can extract details
>>>>>>>>>>>>>>> from that node and ie. configure the PHY using the PHY subsystem.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Signed-off-by: Marek Vasut <marek.vasut+renesas at gmail.com>
>>>>>>>>>>>>>>> Cc: Simon Glass <sjg at chromium.org>
>>>>>>>>>>>>>>> Cc: Tom Rini <trini at konsulko.com>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Well, bump ?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> This is the only missing patch to get my hardware working properly.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I don't think we ever had an agreement on the v1 patch. Simon had a
>>>>>>>>>>>>> long email that pointed out what Linux does seems like a 'fallback' to
>>>>>>>>>>>>> find a node with no compatible string.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Back to this, if we have to go with this way, please create a test
>>>>>>>>>>>>> case to cover this scenario.
>>>>>>>>>>>>
>>>>>>>>>>>> The fact that it works on a particular board is not tested enough?
>>>>>>>>>>>> Do we need a custom, special, synthetic test ?
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> I believe that's always been the requirement against the DM code
>>>>>>>>>>> changes. I was requested in the past when I changed something in the
>>>>>>>>>>> DM and I see other people were asked to do so. Like Alex said, it does
>>>>>>>>>>> not mean this patch was not tested enough, but to ensure future
>>>>>>>>>>> commits won't break this.
>>>>>>>>>>
>>>>>>>>>> So, do you have any suggestion how to implement this test ? It seems
>>>>>>>>>> Alex posed the same question. It doesn't seem to be trivial in the
>>>>>>>>>> context of sandbox.
>>>>>>>>>
>>>>>>>>> I suppose you need a PCI_DEVICE() declaration for sandbox, with an
>>>>>>>>> associated DT node and no compatible string. Then check that you can
>>>>>>>>> locate the device and that it read a DT property correctly.
>>>>>>>>
>>>>>>>> Is there any example of this stuff already ?
>>>>>>>
>>>>>>> See the bottom of swap_case.c. You might be able to add a new one of those,
>>>>>>>
>>>>>>> If you look at pci-controller2 in test.dts it has a device with a
>>>>>>> compatible string. You could try adding a second device with no
>>>>>>> compatible string.
>>>>>>
>>>>>> And how does that test anything ?
>>>>>
>>>>> You can test that your code actually attaches the DT node to the
>>>>> probed device. Without you code the test would fail. Wit it, it would
>>>>> pass.
>>>>
>>>> Well it won't, because the sandbox swap_case.c requires the compatible.
>>>> This all seems like a big hack to support virtual PCI devices.
>>>>
>>>> The driver binds with a compatible and then pins the read/write config
>>>> reg accessors to emulate their return values. Those include PCI IDs. So
>>>> you cannot instantiate virtual PCI device without this compatible string
>>>> and thus also cannot write such a test easily.
>>>>
>>>> Now I also understand where this whole discussion about compatible
>>>> strings came from though.
>>>
>>> The compatible string is needed for the emulation driver but not for
>>> the thing that connects to it. However as things stand you can't
>>> attach an emulator to a bus without nesting it under the device which
>>> it attaches to.
>>>
>>> I suspect the best answer is to move the emulator so it is a direct
>>> child of the bus. You would need to update sandbox_pci_get_emul() to
>>> call device_find_first_child() on 'bus' instead of 'dev'.
>>
>> Sounds to me _way_ out of scope for this patchset.
> 
> Dynamic binding is already supported on Sandbox. I guess Simon may
> have missed the part.

Well, where is an example of that ? Because I am not seeing one.

-- 
Best regards,
Marek Vasut