Re: [RFC PATCH v2 2/6] bus/cdx: add the cdx bus driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Aug 22, 2022 at 01:21:47PM +0000, Gupta, Nipun wrote:
> [AMD Official Use Only - General]
> 
> 
> 
> > -----Original Message-----
> > From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Sent: Wednesday, August 17, 2022 9:03 PM
> > To: Gupta, Nipun <Nipun.Gupta@xxxxxxx>
> > Cc: robh+dt@xxxxxxxxxx; krzysztof.kozlowski+dt@xxxxxxxxxx; rafael@xxxxxxxxxx;
> > eric.auger@xxxxxxxxxx; alex.williamson@xxxxxxxxxx; cohuck@xxxxxxxxxx;
> > Gupta, Puneet (DCG-ENG) <puneet.gupta@xxxxxxx>;
> > song.bao.hua@xxxxxxxxxxxxx; mchehab+huawei@xxxxxxxxxx; maz@xxxxxxxxxx;
> > f.fainelli@xxxxxxxxx; jeffrey.l.hugo@xxxxxxxxx; saravanak@xxxxxxxxxx;
> > Michael.Srba@xxxxxxxxx; mani@xxxxxxxxxx; yishaih@xxxxxxxxxx;
> > jgg@xxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
> > kvm@xxxxxxxxxxxxxxx; okaya@xxxxxxxxxx; Anand, Harpreet
> > <harpreet.anand@xxxxxxx>; Agarwal, Nikhil <nikhil.agarwal@xxxxxxx>;
> > Simek, Michal <michal.simek@xxxxxxx>; git (AMD-Xilinx) <git@xxxxxxx>
> > Subject: Re: [RFC PATCH v2 2/6] bus/cdx: add the cdx bus driver
> > 
> > [CAUTION: External Email]
> > 
> > On Wed, Aug 17, 2022 at 08:35:38PM +0530, Nipun Gupta wrote:
> > > CDX bus driver manages the scanning and populating FPGA
> > > based devices present on the CDX bus.
> > >
> > > The bus driver sets up the basic infrastructure and fetches
> > > the device related information from the firmware. These
> > > devices are registered as platform devices.
> > 
> > Ick, why?  These aren't platform devices, they are CDX devices.  Make
> > them real devices here, don't abuse the platform device interface for
> > things that are not actually on the platform bus.
> 
> CDX is a virtual bus (FW based) which discovers FPGA based platform
> devices based on communication with FW.

virtual busses are fine to have as a real bus in the kernel, no problem
there.

> These devices are essentially platform devices as these are memory mapped
> on system bus, but having a property that they are dynamically discovered
> via FW and are rescannable.

If they are dynamically discoverable and rescannable, then great, it's a
bus in the kernel and NOT a platform device.

> I think your point is correct in the sense that CDX bus is not an actual bus,
> but a FW based mechanism to discover FPGA based platform devices.
> 
> Can you kindly suggest us if we should have the CDX platform device scanning
> code as a CDX bus in "drivers/bus/" folder OR have it in "drivers/fpga/" or
> "drivers/platform/" or which other suitable location?

drivers/cdx/ ?

thanks,

greg k-h



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux