Re: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface

['Greg KH']

On Fri, Mar 06, 2020 at 03:55:46PM -0800, Jolly Shah wrote:
> Hi Greg,
> 
> > ------Original Message------
> > From: 'Greg Kh' <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Sent:  Friday, February 14, 2020 4:52PM
> > To: Jolly Shah <jolly.shah@xxxxxxxxxx>
> > Cc: Rajan Vaja <RAJANV@xxxxxxxxxx>, Ard.biesheuvel@xxxxxxxxxx
> <ard.biesheuvel@xxxxxxxxxx>, Mingo@xxxxxxxxxx <mingo@xxxxxxxxxx>,
> Matt@xxxxxxxxxxxxxxxxxxx <matt@xxxxxxxxxxxxxxxxxxx>, Sudeep.holla@xxxxxxx
> <sudeep.holla@xxxxxxx>, Hkallweit1@xxxxxxxxx <hkallweit1@xxxxxxxxx>,
> Keescook@xxxxxxxxxxxx <keescook@xxxxxxxxxxxx>, Dmitry.torokhov@xxxxxxxxx
> <dmitry.torokhov@xxxxxxxxx>, Michal Simek <michals@xxxxxxxxxx>,
> Linux-arm-kernel@xxxxxxxxxxxxxxxxxxx <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>,
> Linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>
> > Subject: Re: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface
> >
> > On Fri, Feb 14, 2020 at 04:37:16PM -0800, Jolly Shah wrote:
> > > > Just make the direct call to the firmware driver, no need to muck around
> > > > with tables of function pointers.  In fact, with the spectre changes,
> > > > you just made things slower than needed, and you can get back a bunch of
> > > > throughput by removing that whole middle layer.
> > > > 
> > > 
> > > arm,scpi is doing the same way and we thought this approach will be more
> > > acceptable than direct function calls but happy to change as suggested.
> > 
> > Just because one random tiny thing does it the wrong way does not mean
> > to focus on that design pattern and ignore the thousands of other
> > apis/interfaces in the kernel that do not do it that way :)
> > 
> > > > So go do that first please, before adding any new stuff.
> > > > 
> > > > Now for the ioctl, yeah, that's not a "normal" pattern either.  But
> > > > right now you only have 2 "different" ioctls that you call.  So why not
> > > > just turn those 2 into real function calls as well that then makes the
> > > > "ioctl" call to the hardware?  That makes things a lot more obvious on
> > > > the kernel driver side exactly what is going on.
> > > > 
> > > 
> > > Sure as i understand firmware driver will provide real function calls to be
> > > used by user drivers and underneath it will call ioctl for desired
> > > operation. Please correct if I misunderstood.
> > 
> > You do not misunderstand.
> 
> Submitted v3 with required changes. Please review.

Will do, when I get to it, relax :)