linux-kernel - Re: [PATCH v3 08/21] fpga: add Intel FPGA DFL PCIe device

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Date:   Thu, 1 Feb 2018 15:59:21 -0600
From:   Alan Tull <atull@...nel.org>
To:     Wu Hao <hao.wu@...el.com>
Cc:     David Laight <David.Laight@...lab.com>,
        "mdf@...nel.org" <mdf@...nel.org>,
        "linux-fpga@...r.kernel.org" <linux-fpga@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-api@...r.kernel.org" <linux-api@...r.kernel.org>,
        "luwei.kang@...el.com" <luwei.kang@...el.com>,
        "yi.z.zhang@...el.com" <yi.z.zhang@...el.com>,
        Tim Whisonant <tim.whisonant@...el.com>,
        Enno Luebbers <enno.luebbers@...el.com>,
        Shiva Rao <shiva.rao@...el.com>,
        Christopher Rauer <christopher.rauer@...el.com>,
        Xiao Guangrong <guangrong.xiao@...ux.intel.com>
Subject: Re: [PATCH v3 08/21] fpga: add Intel FPGA DFL PCIe device

On Tue, Dec 5, 2017 at 11:30 PM, Wu Hao <hao.wu@...el.com> wrote:
> On Tue, Dec 05, 2017 at 11:00:22AM -0600, Alan Tull wrote:
>> On Mon, Dec 4, 2017 at 9:33 PM, Wu Hao <hao.wu@...el.com> wrote:
>> > On Mon, Dec 04, 2017 at 01:46:59PM -0600, Alan Tull wrote:
>> >> On Mon, Nov 27, 2017 at 9:15 PM, Wu Hao <hao.wu@...el.com> wrote:
>> >> > On Mon, Nov 27, 2017 at 10:28:04AM +0000, David Laight wrote:
>> >> >> From: Wu Hao
>> >> >> > Sent: 27 November 2017 06:42
>> >> >> > From: Zhang Yi <yi.z.zhang@...el.com>
>> >> >> >
>> >> >> > The Intel FPGA device appears as a PCIe device on the system. This patch
>> >> >> > implements the basic framework of the driver for Intel PCIe device which
>> >> >> > is located between CPU and Accelerated Function Units (AFUs), and has
>> >> >> > the Device Feature List (DFL) implemented in its MMIO space.
>> >> >>
>> >> >> This ought to have a better name than 'Intel FPGA'.
>> >> >> An fpga can be used for all sorts of things, this looks like
>> >> >> a very specific architecture using a common VHDL environment to
>> >> >> allow certain types of user VHDL be accessed over PCIe.
>> >> >
>> >> > Hi David
>> >> >
>> >> > This patch adds a pcie device driver for Intel FPGA devices which implements
>> >> > the DFL, e.g Intel Server Platform with In-package FPGA and Intel FPGA PCIe
>> >> > Acceleration Cards. They are pcie devices, and all have DFL implemented in
>> >> > the MMIO space, so we would like to use one kernel driver to handle them.
>> >> >
>> >> > With this full patchset, it just provides user the interfaces to configure
>> >> > and access the FPGA accelerators on Intel DFL based FPGA devices. For sure,
>> >> > users can develop and build their own logics via tools provided by Intel,
>> >> > program them to accelerators on these Intel FPGA devices, and access them
>> >> > for their workloads.
>> >>
>> >> I don't see anything Intel specific here.  This could all be named dfl-*
>> >
>> > The maybe some device specific things, e.g Intel FPGA devices supported by this
>> > driver always have FME DFL at the beginning on the BAR0 for PF device.

I'm thinking that another user could add their PCI id's and a static
FPGA image that has a DFL in the right place for this to work for
them.

>> >
>> > But I think this should be the right direction for better code reuse, it could
>> > save efforts for other vendors who want to use DFL and follow the same way.

I appreciate your understanding here.

>> >
>> > Thanks for the comments. I will rename this driver in the next version.
>>
>> Thanks!
>>
>> Regarding file names, it seems like the files added to drivers/fpga
>> could be uniformly named dfl-*.[ch].  Some are fpga-dfl-*.[ch] while
>> other are currently dfl-*.[ch] currently.
>
> Sure, will have all related drivers files renamed to dfl-*.[ch].

Actually, I'll reverse that a bit.  The enumeration code, including
the pcie part is all sufficiently general to run on anything that has
a DFL struct located in the right place.  But individual feature
drivers (currently only the fme-mgr) will be vendor specific and could
be named intel-*.

Alan