Re: [PATCH v3 20/24] firmware: xilinx: Add APIs to read/write GGS/PGGS registers

From: Greg KH <gregkh@linuxfoundation.org>
To: Rajan Vaja <RAJANV@xilinx.com>
Cc: Jolly Shah <JOLLYS@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 v3 20/24] firmware: xilinx: Add APIs to read/write GGS/PGGS registers
Date: Wed, 18 Mar 2020 13:50:03 +0100	[thread overview]
Message-ID: <20200318125003.GA2727094@kroah.com> (raw)
In-Reply-To: <BYAPR02MB4055DE6560EFDCFD0EBFD8E2B7F70@BYAPR02MB4055.namprd02.prod.outlook.com>

On Wed, Mar 18, 2020 at 12:41:46PM +0000, Rajan Vaja wrote:
> Hi Greg,
> 
> Thanks for applying patches and review.
> 
> Please see my comment inline.
> 
> > -----Original Message-----
> > From: Greg KH <gregkh@linuxfoundation.org>
> > Sent: 18 March 2020 05:22 PM
> > To: Jolly Shah <JOLLYS@xilinx.com>
> > Cc: ard.biesheuvel@linaro.org; mingo@kernel.org; matt@codeblueprint.co.uk;
> > sudeep.holla@arm.com; hkallweit1@gmail.com; keescook@chromium.org;
> > dmitry.torokhov@gmail.com; Michal Simek <michals@xilinx.com>; Rajan Vaja
> > <RAJANV@xilinx.com>; linux-arm-kernel@lists.infradead.org; linux-
> > kernel@vger.kernel.org; Rajan Vaja <RAJANV@xilinx.com>
> > Subject: Re: [PATCH v3 20/24] firmware: xilinx: Add APIs to read/write GGS/PGGS
> > registers
> > 
> > CAUTION: This message has originated from an External Source. Please use
> > proper judgment and caution when opening attachments, clicking links, or
> > responding to this email.
> > 
> > 
> > On Fri, Mar 06, 2020 at 03:47:28PM -0800, Jolly Shah wrote:
> > > --- a/include/linux/firmware/xlnx-zynqmp.h
> > > +++ b/include/linux/firmware/xlnx-zynqmp.h
> > > @@ -105,6 +105,10 @@ enum pm_ioctl_id {
> > >       IOCTL_GET_PLL_FRAC_MODE,
> > >       IOCTL_SET_PLL_FRAC_DATA,
> > >       IOCTL_GET_PLL_FRAC_DATA,
> > > +     IOCTL_WRITE_GGS,
> > > +     IOCTL_READ_GGS,
> > > +     IOCTL_WRITE_PGGS,
> > > +     IOCTL_READ_PGGS,
> > 
> > You do not have explicit numbers here?  Bold :)
> [Rajan] Here new IOCTL IDs are continuous so didn't mention explicit number.

Yes, but is that guaranteed by the compiler?  I keep getting conflicting
advice with that.

> Are asking for adding numbers like below:
> enum pm_ioctl_id {
>       ...
>       IOCTL_GET_PLL_FRAC_DATA = 11,
>       IOCTL_WRITE_GGS = 12,
>       ....
> }

Yes please, especially as your firmware is expecting the explicit values
here, right?  That way you _know_ everything is correct.

thanks,

greg k-h