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Subject: Re: [PATCH v9 1/2] uio: uio_dfl: add userspace i/o driver for DFL bus
To:     Xu Yilun <yilun.xu@intel.com>, Moritz Fischer <mdf@kernel.org>
Cc:     gregkh@linuxfoundation.org, linux-fpga@vger.kernel.org,
        linux-kernel@vger.kernel.org, lgoncalv@redhat.com, hao.wu@intel.com
References: <1611564563-9665-1-git-send-email-yilun.xu@intel.com>
 <1611564563-9665-2-git-send-email-yilun.xu@intel.com>
 <e9bb1ff8-f630-f1a3-985c-7e51369a733f@redhat.com>
 <YA98/8r+yOCurHAJ@epycbox.lan> <20210126024005.GB3907@yilunxu-OptiPlex-7050>
From:   Tom Rix <trix@redhat.com>
Message-ID: <2453fe70-9459-f260-305c-3ca5d6fa8aff@redhat.com>
Date:   Tue, 26 Jan 2021 05:49:14 -0800
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On 1/25/21 6:40 PM, Xu Yilun wrote:
> On Mon, Jan 25, 2021 at 06:22:55PM -0800, Moritz Fischer wrote:
>> On Mon, Jan 25, 2021 at 11:00:38AM -0800, Tom Rix wrote:
>>> On 1/25/21 12:49 AM, Xu Yilun wrote:
>>>> This patch supports the DFL drivers be written in userspace. This is
>>>> realized by exposing the userspace I/O device interfaces.
>>>>
>>>> The driver now only binds the ether group feature, which has no irq. So
>>>> the irq support is not implemented yet.
>>>>
>>>> Signed-off-by: Xu Yilun <yilun.xu@intel.com>
>>>> ---
>>>> v9: switch to add a uio driver in drivers/uio
>>>> ---
>>>>  drivers/uio/Kconfig   | 13 ++++++++++
>>>>  drivers/uio/Makefile  |  1 +
>>>>  drivers/uio/uio_dfl.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>> You should add this to the MAINTAINERS file.
>> This is covered by MAINTAINERS under drivers/uio.
> Yes. But is it OK I also add the file in "FPGA DFL DRIVERS"? So DFL
> developers would also be aware if there is change. It is a little
> different from other feature driver, it is like a generic driver for
> DFL bus.

I think the issue is which maintainer branch this gets merged into.

It would not be linux-fpga.

It is this sort of driver I want to add to FPGA SUBDEVICES list described here

https://lore.kernel.org/linux-fpga/96a9d3d9-6091-47c9-21f9-0cfdd9464732@redhat.com/

Where the driver is maintained in the subsystem but reviewed in linux-fpga.

Tom

>>>>  3 files changed, 80 insertions(+)
>>>>  create mode 100644 drivers/uio/uio_dfl.c
>>>>
>>>> diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
>>>> index 202ee81..44778f8 100644
>>>> --- a/drivers/uio/Kconfig
>>>> +++ b/drivers/uio/Kconfig
>>>> @@ -165,4 +165,17 @@ config UIO_HV_GENERIC
>>>>  	  to network and storage devices from userspace.
>>>>  
>>>>  	  If you compile this as a module, it will be called uio_hv_generic.
>>>> +
>>>> +config UIO_DFL
>>>> +	tristate "Generic driver for DFL bus"
>>> The term 'DFL' will be unknown to folks in drivers/uio
>>>
>>> I think it would be better if DFL was always prefixed 'FPGA DFL'
>>>
>>>> +	depends on FPGA_DFL
>>>> +	help
>>>> +	  Generic DFL (Device Feature List) driver for Userspace I/O devices.
>>>> +	  It is useful to provide direct access to DFL devices from userspace.
>>>> +	  A sample userspace application using this driver is available for
>>>> +	  download in a git repository:
>>>> +
>>>> +	    git clone https://github.com/OPAE/opae-sdk.git
>>>> +
>>>> +	  If you compile this as a module, it will be called uio_dfl.
>> I'm not sure KConfig is the right place for this.
> Do you mean the OPAE link? I see several uio drivers provide their
> userspace application link in Kconfig. I guess the uio drivers are
> selected for these applications so it may be better pointing out where
> they are.
>
> Thanks,
> Yilun
>