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

[Marek Vasut]

On 09/19/2018 11:41 AM, Bin Meng wrote:
> Hi Marek,
> 
> On Wed, Sep 19, 2018 at 5:34 PM Marek Vasut <marek.vasut at gmail.com> wrote:
>>
>> 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.
>>
> 
> I already pointed out in the previous email. In
> arch/sandbox/dts/test.dts, the 2nd PCI controller has two swap_case
> devices and the 3rd controller has one.

By "second" you mean pci1: or pci2: ? Because pci1: is second , after
pci0 . It'd really help if you were clearer in what you refer to.

> In swap_case.c, U_BOOT_PCI_DEVICE() is there which is also a clear
> sign that the driver supports dynamic binding. Of course, the driver
> supports "compatible" too as you noticed.

Are you talking about sandbox,dev-info DT property here ?

-- 
Best regards,
Marek Vasut