linux-kernel - Re: [PATCH v6 2/2] Documentation: fpga: dfl: Add description for DFL UIO support

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Message-ID: <20210118031030.GB8153@yilunxu-OptiPlex-7050>
Date:   Mon, 18 Jan 2021 11:10:30 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Moritz Fischer <mdf@...nel.org>
Cc:     linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, trix@...hat.com, lgoncalv@...hat.com,
        hao.wu@...el.com, yilun.xu@...el.com
Subject: Re: [PATCH v6 2/2] Documentation: fpga: dfl: Add description for DFL
  UIO support

On Sat, Jan 16, 2021 at 07:57:48PM -0800, Moritz Fischer wrote:
> Hi Xu,
> 
> On Wed, Jan 13, 2021 at 09:54:08AM +0800, 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.
> > v3: some documentation fixes.
> > v4: documentation change since the driver matching is changed.
> > v5: no change.
> > v6: improve the title of the userspace driver support section.
> >     some word improvement.
> > ---
> >  Documentation/fpga/dfl.rst | 24 ++++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> > 
> > diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> > index 0404fe6..c33b6d0 100644
> > --- a/Documentation/fpga/dfl.rst
> > +++ b/Documentation/fpga/dfl.rst
> > @@ -7,6 +7,7 @@ Authors:
> >  - Enno Luebbers <enno.luebbers@...el.com>
> >  - Xiao Guangrong <guangrong.xiao@...ux.intel.com>
> >  - Wu Hao <hao.wu@...el.com>
> > +- Xu Yilun <yilun.xu@...el.com>
> >  
> >  The Device Feature List (DFL) FPGA framework (and drivers according to
> >  this framework) hides the very details of low layer hardwares and provides
> > @@ -502,6 +503,29 @@ FME Partial Reconfiguration Sub Feature driver (see drivers/fpga/dfl-fme-pr.c)
> >  could be a reference.
> >  
> >  
> > +Userspace driver support for DFL devices
> > +========================================
> > +The purpose of an FPGA is to be reprogrammed with newly developed hardware
> > +components. New hardware can 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.
> > +* Some hardware is designed for specific purposes and does not fit into one of
> > +  the standard kernel subsystems.
> > +
> > +This requires direct access to MMIO space and interrupt handling from
> > +userspace. The dfl-uio-pdev module exposes the UIO device interfaces for this
> > +purpose. It adds the uio_pdrv_genirq platform device with the resources of
> > +the DFL feature, and lets the generic UIO platform device driver provide UIO
> > +support to userspace.
> > +
> > +FPGA_DFL_UIO_PDEV should be selected to enable the dfl-uio-pdev module driver.
> > +To support a new DFL feature been directly accessed via UIO, its feature id
> > +should be added to the driver's id_table.
> > +
> > +
> >  Open discussion
> >  ===============
> >  FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial reconfiguration
> > -- 
> > 2.7.4
> > 
> 
> Looks fine to me, can you resend with changes for the other patch?

Yes, I will. I may wait for a while to check more comments from Greg.

Thanks,
Yilun