Re: [PATCH v2 20/22] fpga: intel: afu add FPGA_GET_API_VERSION/CHECK_EXTENSION ioctls support

[Wu Hao <hao.wu@intel.com>]

On Thu, Aug 17, 2017 at 12:12:00PM -0700, Moritz Fischer wrote:
> Hi,
> 
> On Sun, Jun 25, 2017 at 6:52 PM, Wu Hao <hao.wu@intel.com> wrote:
> > FPGA_GET_API_VERSION and FPGA_CHECK_EXTENSION ioctls are common ones which
> > need to be supported by all feature devices drivers including FME and AFU.
> > This patch implements above 2 ioctls in Intel FPGA Accelerated Function
> > Unit (AFU) driver.
> >
> > Signed-off-by: Tim Whisonant <tim.whisonant@intel.com>
> > Signed-off-by: Enno Luebbers <enno.luebbers@intel.com>
> > Signed-off-by: Shiva Rao <shiva.rao@intel.com>
> > Signed-off-by: Christopher Rauer <christopher.rauer@intel.com>
> > Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> > Signed-off-by: Wu Hao <hao.wu@intel.com>
> > ---
> > v2: rebased
> > ---
> >  drivers/fpga/intel-afu-main.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/fpga/intel-afu-main.c b/drivers/fpga/intel-afu-main.c
> > index 2a17cde..22f77f2 100644
> > --- a/drivers/fpga/intel-afu-main.c
> > +++ b/drivers/fpga/intel-afu-main.c
> > @@ -122,6 +122,13 @@ static int afu_release(struct inode *inode, struct file *filp)
> >         return 0;
> >  }
> >
> > +static long afu_ioctl_check_extension(struct feature_platform_data *pdata,
> > +                                    unsigned long arg)
> > +{
> > +       /* No extension support for now */
> 
> Do you maybe make that an -ENOTSUPP or -EINVAL then?

Hi Moritz

User will use this ioctl to check if extension X is supported. It always returns 0
means any extension indicated by the arg, is not supported.

I think we don't have to return an -ENOTSUPP or -EINVAL here, which may confuse
the enduser. : )

Thanks
Hao

> > +       return 0;
> > +}
> > +
> >  static long afu_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> >  {
> >         struct platform_device *pdev = filp->private_data;
> > @@ -132,6 +139,10 @@ static long afu_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
> >         dev_dbg(&pdev->dev, "%s cmd 0x%x\n", __func__, cmd);
> >
> >         switch (cmd) {
> > +       case FPGA_GET_API_VERSION:
> > +               return FPGA_API_VERSION;
> > +       case FPGA_CHECK_EXTENSION:
> > +               return afu_ioctl_check_extension(pdata, arg);
> >         default:
> >                 /*
> >                  * Let sub-feature's ioctl function to handle the cmd
> > --
> > 1.8.3.1
> >
> > --
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> 
> Thanks,
> 
> Moritz