linux-kernel - Re: [PATCH v3 0/2] usb: xhci: Load Raspberry Pi 4 VL805's firmware

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Date:   Thu, 4 Jun 2020 13:52:58 +0200
From:   Marek Vasut <marex@...x.de>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>, mbrugger@...e.com,
        u-boot@...ts.denx.de, bmeng.cn@...il.com,
        linux-kernel@...r.kernel.org
Cc:     sjg@...omium.org, m.szyprowski@...sung.com, s.nawrocki@...sung.com,
        mark.kettenis@...all.nl
Subject: Re: [PATCH v3 0/2] usb: xhci: Load Raspberry Pi 4 VL805's firmware

On 6/4/20 1:18 PM, Nicolas Saenz Julienne wrote:
> On Mon, 2020-06-01 at 17:27 +0200, Marek Vasut wrote:
>> On 6/1/20 4:41 PM, Nicolas Saenz Julienne wrote:
>>> On Mon, 2020-06-01 at 13:12 +0200, Marek Vasut wrote:
>>>> On 6/1/20 1:09 PM, Nicolas Saenz Julienne wrote:
>>>>> On Mon, 2020-06-01 at 12:53 +0200, Marek Vasut wrote:
>>>>>> On 6/1/20 12:47 PM, Nicolas Saenz Julienne wrote:
>>>>>>> On Tue, 2020-05-05 at 18:26 +0200, Nicolas Saenz Julienne wrote:
>>>>>>>> Newer revisions of the RPi4 need their xHCI chip, VL805, firmware
>>>>>>>> to
>>>>>>>> be
>>>>>>>> loaded explicitly. Earlier versions didn't need that as they where
>>>>>>>> using
>>>>>>>> an EEPROM for that purpose. This series takes care of setting up
>>>>>>>> the
>>>>>>>> relevant infrastructure and run the firmware loading routine at
>>>>>>>> the
>>>>>>>> right moment.
>>>>>>>>
>>>>>>>> Note that this builds on top of Sylwester Nawrocki's "USB host
>>>>>>>> support
>>>>>>>> for Raspberry Pi 4 board" series.
>>>>>>>>
>>>>>>>> ---
>>>>>>>
>>>>>>> Please don't forget about this series. The new 8GB RPi4 contains
>>>>>>> this HW
>>>>>>> design
>>>>>>> change and USB will not work without it. See this discussion on the
>>>>>>> downstream
>>>>>>> kernel github, where other OS/bootloaders are hitting the issue:
>>>>>>>
>>>>>>> https://github.com/raspberrypi/firmware/issues/1402
>>>>>>>
>>>>>>> Otherwise, the Linux version of this is already in linux-next:
>>>>>>>
>>>>>>>
>>>
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/drivers/usb/host/pci-quirks.c?h=next-20200529&id=c65822fef4adc0ba40c37a47337376ce75f7a7bc
>>>>>> We're already at 2020.07-rc3 , so unless this is a bugfix (does not
>>>>>> look
>>>>>> that way), this will have to wait for next release cycle.
>>>>>
>>>>> Of course. As long as it eventually gets in I'm happy (not implying this
>>>>> specific series is flawless, but the overall mechanism). I'm just
>>>>> worried
>>>>> this
>>>>> gets lost.
>>>>>
>>>>>> Also, it seems
>>>>>> there was a lengthy ongoing discussion, is that already sorted out ?
>>>>>
>>>>> Well, there was some discussion on how to incorporate the platform
>>>>> specific
>>>>> callback into XCHI's code. Which this revision of the series addresses.
>>>>> But,
>>>>> IIRC, that's pretty much it as far as discussion is concerned.
>>>>
>>>> Oh, right, since the firmware loading hook looks like a reset hook, why
>>>> isn't that implemented via reset controller API instead ?
>>>
>>> That could be pretty clean, I hadn't though about it that way. Some
>>> questions:
>>>
>>> - Being a PCIe device the XHCI controller doesn't show up in the device-
>>> tree. I
>>>   guess it could be added as a child node of pcie-brcmstb, but is that even
>>>   acceptable?
>>
>> Yes, there are other such DTs .
>>
>>> - Same goes for xhci-pci being a consumer of the reset controller. Given the
>>>   reset scheme is board specific (the chip can be found all over the place,
>>> but
>>>   the firmware loading scheme is 100% RPi specific), to what extent we can
>>>   introduce that as a binding?
>>
>> I'm not sure what you're asking me here, you'll just have some reset
>> controller in a DT and a phandle from the xhci-controller to this reset
>> controller.
> 
> Sorry I wasn't clear, overall my concern here is that xhic-pci maintainers,
> both in u-boot y linux (as I'd like to have the same solution on both sides,
> since it involves changes in dt), might see it as too platform specific to add
> it into an otherwise generic xhci-pci implmentation.
> 
> But nevermind, I'll just post the series and see what happens :).

I think it should be OK, thanks.