Re: [PATCH net-next V2 19/23] ptp: tilegx: convert to the 64 bit get/set time methods.

From: Richard Cochran <richardcochran@gmail.com>
To: Chris Metcalf <cmetcalf@ezchip.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Amir Vadai" <amirv@mellanox.com>,
	"Ariel Elior" <ariel.elior@qlogic.com>,
	"Arnd Bergmann" <arnd@linaro.org>,
	"Baolin Wang" <baolin.wang@linaro.org>,
	"Ben Hutchings" <ben@decadent.org.uk>,
	"Bruce Allan" <bruce.w.allan@intel.com>,
	"Carolyn Wyborny" <carolyn.wyborny@intel.com>,
	"David Miller" <davem@davemloft.net>,
	"Frank Li" <Frank.Li@freescale.com>,
	"Giuseppe Cavallaro" <peppe.cavallaro@st.com>,
	"Jeff Kirsher" <jeffrey.t.kirsher@intel.com>,
	"John Stultz" <john.stultz@linaro.org>,
	"Luwei Zhou" <b45643@freescale.com>,
	"Matthew Vick" <matthew.vick@intel.com>,
	"Michael Chan" <mchan@broadcom.com>,
	"Prashant Sreedharan" <prashant@broadcom.com>,
	"Shradha Shah" <sshah@solarflare.com>,
	"Solarflare linux maintainers" <linux-net-drivers@solarflare.com>,
	"Sonic Zhang" <sonic.zhang@analog.com>,
	"Stefan Sørensen" <stefan.sorensen@spectralink.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Tom Lendacky" <thomas.lendacky@amd.com>
Subject: Re: [PATCH net-next V2 19/23] ptp: tilegx: convert to the 64 bit get/set time methods.
Date: Mon, 23 Mar 2015 17:58:39 +0100	[thread overview]
Message-ID: <20150323165839.GA4330@localhost.localdomain> (raw)
In-Reply-To: <551038FB.2070200@ezchip.com>

On Mon, Mar 23, 2015 at 12:02:03PM -0400, Chris Metcalf wrote:
> This driver is 64-bit only.  Would it make more sense to just change
> the accessors from gettime/settime to gettime/settime64 and nothing
> else, i.e. rely on the current behavior that timespec and timespec64
> are the same type, and trust the compiler to fail it if somehow someone
> tried to build this driver into a 32-bit kernel?

On the one hand, I think the best way would be for
gxio_mpipe_get/set_timestamp to also take a timespec64, because it
makes the width clear.  With a plain old timespec, you have to
remember whether you are 64 bit or not.  However, but I couldn't tell
if changing gxio_mpipe_get/set_timestamp would work for other callers
or not.

If the driver is 64 bit only, shouldn't that be reflected in the
Kconfig?

On the other hand, I wouldn't mind the change you suggest, if it were
super obvious that the code is 64 bit only.  It was not obvious to me.

Thanks,
Richard