linux-kernel - Re: [PATCH v2 2/2] Documentation: fpga: dfl: Add description for DFL UIO support

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Date:   Tue, 15 Dec 2020 10:22:06 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Tom Rix <trix@...hat.com>
Cc:     mdf@...nel.org, linux-fpga@...r.kernel.org,
        linux-kernel@...r.kernel.org, gregkh@...uxfoundation.org,
        lgoncalv@...hat.com, hao.wu@...el.com
Subject: Re: [PATCH v2 2/2] Documentation: fpga: dfl: Add description for DFL
  UIO support

On Mon, Dec 14, 2020 at 02:14:56PM -0800, Tom Rix wrote:
> 
> On 12/13/20 7:36 PM, Xu Yilun wrote:
> > This patch adds description for UIO support for dfl devices on DFL
> > bus.
> >
> > Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> > ---
> > v2: no doc in v1, add it for v2.
> > ---
> >  Documentation/fpga/dfl.rst | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> Should add your self in the authors list.

OK.

> >
> > diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> > index 0404fe6..a15e81e 100644
> > --- a/Documentation/fpga/dfl.rst
> > +++ b/Documentation/fpga/dfl.rst
> > @@ -502,6 +502,29 @@ FME Partial Reconfiguration Sub Feature driver (see drivers/fpga/dfl-fme-pr.c)
> >  could be a reference.
> >  
> >  
> > +UIO support for DFL devices
> > +===========================
> > +The FPGA is open for users to be reprogramed with newly developed hardware
> 
> The purpose of an FPGA is to be reprogrammed with newly developed hardware
> 
> components.  New hardware can

Will change it.

> 
> > +components. They could instantiate a new private feature in the DFL, and then
> > +get a DFL device in their system. In some cases users may need a userspace
> > +driver for the DFL device:
> > +
> > +* Users may need to run some diagnostic test for their hardwares.
> * Users may prototype the kernel driver in user space.

Could we just add the line rather than replacing the previous line? I think this
comment is describing a different usecase.

> > +* Some hardware is designed for specific purposes and does not fit into one of
> > +  the standard kernel subsystems.
> > +
> > +This requires the direct access to the MMIO space and interrupt handling in
> > +userspace. We implemented a dfl-uio-pdev module which exposes the UIO device
> The dfl-uio-pdev module exposes

Will change it.

> > +interfaces. It adds the uio_pdrv_genirq platform device with the resources of
> > +the DFL device, and let the generic UIO platform device driver provide UIO
> the DLF device, and lets

Will change it.

> > +support to userspace.
> Use FPGA_DFL_UIO_PDEV to enable this feature.

I didn't get your idea for this.

> > +
> > +The DFL UIO driver has a special matching algorithem. It will match any DFL
> > +device which could not be handled by other DFL drivers. In this way, it will
> > +not impact the functionality of the features which are already supported by the
> > +system.
> (not sure if this section is needed)

I think we may keep it.

Thanks,
Yilun