From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH 1/5] ARM: DT: tegra114: add APB DMA controller DT entry Date: Fri, 08 Mar 2013 10:51:08 -0700 Message-ID: <513A250C.1000202@wwwdotorg.org> References: <1362750782-15174-1-git-send-email-ldewangan@nvidia.com> <1362750782-15174-2-git-send-email-ldewangan@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1362750782-15174-2-git-send-email-ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Laxman Dewangan Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, pdeschrijver-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 03/08/2013 06:52 AM, Laxman Dewangan wrote: > NVIDIA's Tegra114 has 32 channels APB DMA controller. Add DT entry for > APB DMA controllers and make it compatible with "nvidia,tegra114-apbdma". > diff --git a/arch/arm/boot/dts/tegra114.dtsi b/arch/arm/boot/dts/tegra114.dtsi > + apbdma: dma { > + compatible = "nvidia,tegra114-apbdma"; So I know that the Tegra114 HW has a new channel-pause feature, which the driver /can/ use. However, if the driver didn't know about that feature, and continued to use the global-pause feature, would it still work fine? In other words, is the Tegra114 HW 100% backwards-compatible with the Tegra30 HW, it's just that there are new features that SW could optionally use? If that is true, then we should also include "nvidia,tegra30-apbdma" in the compatible value.