RE: [PATCH V3 02/12] misc: xilinx-sdfec: add core driver

[Dragan Cvetic]

> -----Original Message-----
> From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> Sent: Monday 6 May 2019 13:34
> To: Dragan Cvetic <draganc@xxxxxxxxxx>
> Cc: arnd@xxxxxxxx; Michal Simek <michals@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> mark.rutland@xxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Derek Kiernan <dkiernan@xxxxxxxxxx>
> Subject: Re: [PATCH V3 02/12] misc: xilinx-sdfec: add core driver
> 
> On Mon, May 06, 2019 at 12:23:56PM +0000, Dragan Cvetic wrote:
> >
> >
> > > -----Original Message-----
> > > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> > > Sent: Saturday 4 May 2019 08:55
> > > To: Dragan Cvetic <draganc@xxxxxxxxxx>
> > > Cc: arnd@xxxxxxxx; Michal Simek <michals@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> > > mark.rutland@xxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Derek Kiernan <dkiernan@xxxxxxxxxx>
> > > Subject: Re: [PATCH V3 02/12] misc: xilinx-sdfec: add core driver
> > >
> > > On Fri, May 03, 2019 at 04:41:21PM +0000, Dragan Cvetic wrote:
> > > > Hi Greg,
> > > >
> > > > Please find my inline comments below,
> > > >
> > > > Regards
> > > > Dragan
> > > >
> > > > > -----Original Message-----
> > > > > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx]
> > > > > Sent: Thursday 2 May 2019 18:20
> > > > > To: Dragan Cvetic <draganc@xxxxxxxxxx>
> > > > > Cc: arnd@xxxxxxxx; Michal Simek <michals@xxxxxxxxxx>; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; robh+dt@xxxxxxxxxx;
> > > > > mark.rutland@xxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Derek Kiernan <dkiernan@xxxxxxxxxx>
> > > > > Subject: Re: [PATCH V3 02/12] misc: xilinx-sdfec: add core driver
> > > > >
> > > > > On Sat, Apr 27, 2019 at 11:04:56PM +0100, Dragan Cvetic wrote:
> > > > > > +#define DRIVER_NAME "xilinx_sdfec"
> > > > > > +#define DRIVER_VERSION "0.3"
> > > > >
> > > > > Version means nothing with the driver in the kernel tree, please remove
> > > > > it.
> > > >
> > > > Will be removed. Thank you.
> > > >
> > > > >
> > > > > > +#define DRIVER_MAX_DEV BIT(MINORBITS)
> > > > >
> > > > > Why this number?  Why limit yourself to any number?
> > > > >
> > > >
> > > > There can be max 8 devices for this driver. I'll change to 8.
> > > >
> > > > > > +
> > > > > > +static struct class *xsdfec_class;
> > > > >
> > > > > Do you really need your own class?
> > > >
> > > > When writing a character device driver, my goal is to create and register an instance
> > > > of that structure associated with a struct file_operations, exposing a set of operations
> > > > to the user-space. One of the steps to make this goal is Create a class for a devices,
> > > > visible in /sys/class/.
> > >
> > > Why do you need a class?  Again, why not just use the misc_device api,
> > > that seems much more relevant here and will make the code a lot simpler.
> > >
> >
> > The driver can have 8 devices in SoC plus more in Programming Logic.
> > It looked logical to group them under the same MAJOR, although they
> > are independent of each other.  Is this argument strong enough to use
> > class?
> 
> Not really :)
> 
> 8 devices is pretty small.  What tool will be trying to talk to all of
> these devices and how was it going to find out what devices were in the
> system?
>

These devices are Forward Error Correction encoder/decoder
and will be part of the RF communication chain. They will be included
in the system through DT. Also, described in DT.
   

> thanks,
> 
> greg k-h