> -----Original Message----- > From: Greg KH [mailto:gregkh@xxxxxxxxxxxxxxxxxxx] > Sent: Tuesday 7 May 2019 10:40 > 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 Tue, May 07, 2019 at 08:48:41AM +0000, Dragan Cvetic wrote: > > > > > > > -----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. > > Userspace doesn't mess with DT. > > I am asking what userspace tool/program is going to be interacting with > these devices through your now-custom api you are creating. Do you have > a link to that software, and how is that code doing the "determine what > device nodes are associated with what devices" logic? > Example code is not public yet, sorry. The index number in the device name is a link to device, see snippet from the example code: #define FEC_DEC "/dev/xsdfec0" dec_fd = open_xsdfec(FEC_DEC); The index number corresponds to the device order in DT. > thanks, > > greg k-h
