From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?B?VGVyamUgQmVyZ3N0csO2bQ==?= Subject: Re: [PATCH v2 27/27] drm/tegra: Add Tegra114 gr2d support Date: Wed, 16 Oct 2013 15:05:41 +0300 Message-ID: <525E8115.7080903@nvidia.com> References: <1381134884-5816-1-git-send-email-treding@nvidia.com> <1381134884-5816-28-git-send-email-treding@nvidia.com> <52587F2D.9070007@wwwdotorg.org> <525B880A.7090802@nvidia.com> <20131014140010.GC16302@ulmo.nvidia.com> <525C3497.6010700@wwwdotorg.org> <20131015083731.GI7856@ulmo.nvidia.com> <525D5CF6.3020600@wwwdotorg.org> <20131016084804.GC21963@ulmo.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20131016084804.GC21963-AwZRO8vwLAwmlAP/+Wk3EA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thierry Reding , Stephen Warren Cc: "dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: devicetree@vger.kernel.org On 16.10.2013 11:48, Thierry Reding wrote: > On Tue, Oct 15, 2013 at 09:19:18AM -0600, Stephen Warren wrote: >> Taking advantage of new functionality isn't the issue. The issue is >> whether a driver that was written purely to the spec of Tegra20 can >> successfully operate on the HW. If it can't, then the HW is not >> compatible with Tegra20. Terje's previous comments sounded like the HW >> is not backwards-compatible, although his more recent comments make it >> sound like only SW policy differences, which shouldn't be part of DT >> anyway. > > Well, as good as I can tell it is backwards-compatible. I've been > testing the code included in this series with the same simple test > program that clears a rectangle on Tegra20, Tegra30 and Tegra114. > > Furthermore our internal register specification files are identical, > with the exception of some whitespace changes for all three generations. > I think that qualifies as backwards-compatible? A driver written for Tegra20 2D works with Tegra114 2D. Not necessarily vice versa, because Tegra114's driver can ask for higher clocks, or it might want to power gate 2D. I mentioned earlier bringup activities. Perhaps Stephen took that in a way I didn't intend. Terje