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

From: 'Greg KH' <gregkh@linuxfoundation.org>
To: Jolly Shah <jolly.shah@xilinx.com>
Cc: Rajan Vaja <RAJANV@xilinx.com>,
	"ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
	"mingo@kernel.org" <mingo@kernel.org>,
	"matt@codeblueprint.co.uk" <matt@codeblueprint.co.uk>,
	"sudeep.holla@arm.com" <sudeep.holla@arm.com>,
	"hkallweit1@gmail.com" <hkallweit1@gmail.com>,
	"keescook@chromium.org" <keescook@chromium.org>,
	"dmitry.torokhov@gmail.com" <dmitry.torokhov@gmail.com>,
	Michal Simek <michals@xilinx.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 1/4] firmware: xilinx: Add sysfs interface
Date: Sat, 7 Mar 2020 09:47:11 +0100	[thread overview]
Message-ID: <20200307084711.GA3877697@kroah.com> (raw)
In-Reply-To: <23a785fd-3874-b71a-c0f5-d117a9058abf@xilinx.com>

On Fri, Mar 06, 2020 at 03:55:46PM -0800, Jolly Shah wrote:
> Hi Greg,
> 
> > ------Original Message------
> > From: 'Greg Kh' <gregkh@linuxfoundation.org>
> > Sent:  Friday, February 14, 2020 4:52PM
> > To: Jolly Shah <jolly.shah@xilinx.com>
> > Cc: Rajan Vaja <RAJANV@xilinx.com>, Ard.biesheuvel@linaro.org
> <ard.biesheuvel@linaro.org>, Mingo@kernel.org <mingo@kernel.org>,
> Matt@codeblueprint.co.uk <matt@codeblueprint.co.uk>, Sudeep.holla@arm.com
> <sudeep.holla@arm.com>, Hkallweit1@gmail.com <hkallweit1@gmail.com>,
> Keescook@chromium.org <keescook@chromium.org>, Dmitry.torokhov@gmail.com
> <dmitry.torokhov@gmail.com>, Michal Simek <michals@xilinx.com>,
> Linux-arm-kernel@lists.infradead.org <linux-arm-kernel@lists.infradead.org>,
> Linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>
> > 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 :)