RE: [PATCH v4 06/24] fpga: dfl: adds fpga_cdev_find_port

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

> On Tue, Feb 13, 2018 at 3:24 AM, Wu Hao <hao.wu@intel.com> wrote:
> 
> Hi Hao,
> 
> > For feature devices, we need a method to find the port dedicated
> > to the device. This patch adds a function fpga_cdev_find_port
> > for this purpose. e.g FPGA Management Engine (FME) Partial
> > Reconfiguration sub feature, it uses this function to find
> > dedicated port on the device for PR function implementation.
> 
> OK, that is very clear now, thanks!  Ack with the minor doc changes below.
> 
> >
> > 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>
> Acked-by: Alan Tull <atull@kernel.org>
> 
> > ---
> > v3: s/fpga_for_each_port/fpga_cdev_find_port/
> >     move fpga_cdev_find_port to fpga-dfl module.
> > v4: improve description in commit message.
> >     add comments to remind user to put_device after use this function.
> > ---
> >  drivers/fpga/dfl.c | 34 ++++++++++++++++++++++++++++++++++
> >  drivers/fpga/dfl.h | 20 ++++++++++++++++++++
> >  2 files changed, 54 insertions(+)
> >
> > diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> > index dcfe5ab..38dc819 100644
> > --- a/drivers/fpga/dfl.c
> > +++ b/drivers/fpga/dfl.c
> > @@ -783,6 +783,40 @@ void fpga_remove_feature_devs(struct fpga_cdev
> *cdev)
> >  }
> >  EXPORT_SYMBOL_GPL(fpga_remove_feature_devs);
> >
> > +/**
> > + * __fpga_cdev_find_port - find a port under given container device
> > + *
> > + * @cdev: container device
> > + * @data: data passed to match function
> > + * @match: match function used to find specific port from the port device list
> > + *
> > + * Find a port device under container device. This function needs to be
> > + * invoked with lock held.
> > + *
> > + * This function returns NULL if the device doesn't match and non-zero if it
> > + * does.
> 
> Good but this would be more brief and more specific and more in line
> with recommended format in Documentation/kernel-doc-nano-HOWTO.txt:
> 
>  * Return: pointer to port's platform device if successful, NULL otherwise.
> 
> > If this function returns non-zero and a reference to the platform
> > + * device of port can be obtained.
> 
> This if..then type sentence is not complete (missing the 'then' part).
> I see where you might have gotten inspiration for it from core.c.
> Probably you could just delete the sentence and all would be clear.

Thanks for the review and the suggestion on this, will update the
comments to fix it.

Hao

> 
> > + *
> > + * NOTE: you will need to drop the device reference with put_device() after
> use.
> > + */
> 
> Good
> 
> Thanks,
> Alan
> 
> > +struct platform_device *
> > +__fpga_cdev_find_port(struct fpga_cdev *cdev, void *data,
> > +                     int (*match)(struct platform_device *, void *))
> > +{
> > +       struct feature_platform_data *pdata;
> > +       struct platform_device *port_dev;
> > +
> > +       list_for_each_entry(pdata, &cdev->port_dev_list, node) {
> > +               port_dev = pdata->dev;
> > +
> > +               if (match(port_dev, data) && get_device(&port_dev->dev))
> > +                       return port_dev;
> > +       }
> > +
> > +       return NULL;
> > +}
> > +EXPORT_SYMBOL_GPL(__fpga_cdev_find_port);
> > +
> >  int fpga_port_id(struct platform_device *pdev)
> >  {
> >         void __iomem *base = get_feature_ioaddr_by_id(&pdev->dev,
> > diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> > index 9b19399..d6ecda1 100644
> > --- a/drivers/fpga/dfl.h
> > +++ b/drivers/fpga/dfl.h
> > @@ -356,4 +356,24 @@ struct fpga_cdev {
> >  struct fpga_cdev *fpga_enumerate_feature_devs(struct fpga_enum_info
> *info);
> >  void fpga_remove_feature_devs(struct fpga_cdev *cdev);
> >
> > +/*
> > + * need to drop the device reference with put_device() after use port
> platform
> > + * device returned by __fpga_cdev_find_port and fpga_cdev_find_port
> functions.
> > + */
> > +struct platform_device *
> > +__fpga_cdev_find_port(struct fpga_cdev *cdev, void *data,
> > +                     int (*match)(struct platform_device *, void *));
> > +
> > +static inline struct platform_device *
> > +fpga_cdev_find_port(struct fpga_cdev *cdev, void *data,
> > +                   int (*match)(struct platform_device *, void *))
> > +{
> > +       struct platform_device *pdev;
> > +
> > +       mutex_lock(&cdev->lock);
> > +       pdev = __fpga_cdev_find_port(cdev, data, match);
> > +       mutex_unlock(&cdev->lock);
> > +
> > +       return pdev;
> > +}
> >  #endif /* __FPGA_DFL_H */
> > --
> > 2.7.4
> >