linux-kernel - Re: [PATCH v1 0/3] Add JH7110 PCIe driver support

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Date:   Mon, 10 Apr 2023 16:58:15 +0800
From:   Minda Chen <minda.chen@...rfivetech.com>
To:     Conor Dooley <conor.dooley@...rochip.com>
CC:     Emil Renner Berthing <emil.renner.berthing@...onical.com>,
        Conor Dooley <conor@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-riscv@...ts.infradead.org>, <linux-pci@...r.kernel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Mason Huo <mason.huo@...rfivetech.com>,
        Leyfoon Tan <leyfoon.tan@...rfivetech.com>,
        Kevin Xie <kevin.xie@...rfivetech.com>,
        <daire.mcnamara@...rochip.com>
Subject: Re: [PATCH v1 0/3] Add JH7110 PCIe driver support



On 2023/4/7 17:57, Conor Dooley wrote:
> Hey Minda,
> 
> On Fri, Apr 07, 2023 at 10:32:51AM +0800, Minda Chen wrote:
>> On 2023/4/6 19:54, Conor Dooley wrote:
>> > On Thu, Apr 06, 2023 at 12:47:41PM +0100, Conor Dooley wrote:
>> >> On Thu, Apr 06, 2023 at 07:11:39PM +0800, Minda Chen wrote:
>> >> > This patchset adds PCIe driver for the StarFive JH7110 SoC.
>> >> > The patch has been tested on the VisionFive 2 board. The test
>> >> > devices include M.2 NVMe SSD and Realtek 8169 Ethernet adapter.
>> >> 
>> >> I was talking with Daire last week about some changes he's working on
>> >> for the microchip driver, and we seemed to recall an off-list email
>> >> sent to Daire & Bjorn about extracting the common PLDA bits from the
>> >> pcie-microchip-host driver to be used with an (at that point)
>> >> unreleased SoC. Perhaps Bjorn has this in his mailbox somewhere still,
>> >> our corporate mail policy scrubs things from over a year ago & I could
>> >> not find it.
>> >>
>> >> I realised that that may actually have been StarFive, and the driver on
>> >> your GitHub [1] certainly felt very familiar to Daire (he said it was
>> >> very similar to his earlier revisions of his driver).
>> >> 
>> >> I've not looked at a diff between this and the version you ship on
>> >> GitHub, but first a quick inspection it mostly just looks like you
>> >> did s/plda/sifive/ on the file.
>> >> 
>> >> I'm obviously not a PCI maintainer, but if there are common bits between
>> >> the two drivers, extracting common bits seems like a good idea to me...
> 
>> Thanks. It is pleasure to using same common codes. Does common bits changes
>> will upstream soon?
> 
> I don't quite get what you mean. We've got some changes that are in
> progress here:
> https://lore.kernel.org/linux-pci/20230111125323.1911373-1-daire.mcnamara@microchip.com/
> We've been quiet there for a while, but Daire's back looking into Robin's
> comments in there about the range parsing/window setup at the moment.
> 
> I'm not sure if that's what you mean though, since you said "common
> bits" & Daire was doing that work in a world where there was no jh7110
> driver in the mix.
> Extracting common bits would be part of the process of adding a new
> driver, as I don't think there's any real reason to do so without
> another in-tree user.
> 
OK, I know extracting common bits is microchip new PCIe driver codes changed.
Just ignore my previous comments.
Maybe I will try to restructuring the driver code according to corporate e-mail which has been sent one year ago.
>> And I see there are many difference between pcie-microchip-host and our codes.
> 
> Right. I'd expect there to be a fair difference between our integrations
> of the IP, and therefore there'll be a bunch of non-shareable bits.
> 
> You need the stg,syscon & phy bits, and the clock/reset handling is
> clearly different too.
> 
>> >> https://github.com/starfive-tech/linux/blob/JH7110_VisionFive2_devel/drivers/pci/controller/pcie-plda.c
> 
> I had a bit of a read through this again today with Daire to check what
> the differences actually are and it *looked* like the main,
> non-implementation related, differences were the extra "event" domain
> that was created to simplify the driver & the bottom half interrupt
> handling.
> That all came out of the review process, so it's likely that some of the
> same requests would be made of you by the PCI maintainers anyway.
> 
Thanks. I will check it and change my codes.
> As an aside, you should probably run checkpatch --strict on this
> submission, there's a rake of coding style "issues" in the new code
> you've added.
> 
I do not run checkpatch with "--strict". I will run with it.
> Cheers,
> Conor.