From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH 4/5] ARM: DT: tegra114: add KBC controller DT entry Date: Fri, 08 Mar 2013 11:04:00 -0700 Message-ID: <513A2810.1070903@wwwdotorg.org> References: <1362750782-15174-1-git-send-email-ldewangan@nvidia.com> <1362750782-15174-5-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: <1362750782-15174-5-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 06:53 AM, Laxman Dewangan wrote: > NVIDIA's Tegra114 SoCs have the matrix keyboard controller which > supports 11x8 type of matrix. The number of rows and columns > are configurable. Earlier Tegra versions supported up to a 16x8 matrix. This feeds into the following defines in the driver: #define KBC_MAX_GPIO 24 #define KBC_MAX_ROW 16 #define KBC_MAX_COL 8 #define KBC_MAX_KEY (KBC_MAX_ROW * KBC_MAX_COL) Given Tegra114 supports /fewer/ pins and rows than earlier chips, I think that makes the HW technically incompatible, since GPIO IDs 19..23 are invalid in this HW but valid earlier. Now in practice I suppose that with a correct DT keyboard map for a Tegra114 device, those extra invalid GPIOs would never be referenced, so this is a little nit-picky, but I still feel we should fix this. So, I'd like to see the KBC driver updated to derive the values for all the defines I listed above from the compatible value. Technically, tegra114.dtsi should not pretend that the Tegra114 KBC is compatible with previous generations either. > diff --git a/arch/arm/boot/dts/tegra114.dtsi b/arch/arm/boot/dts/tegra114.dtsi > + kbc { > + compatible = "nvidia,tegra20-kbc"; Ignoring any of the discussion above, i.e. even if the HW was 100% identical, we should still include a Tegra114 entry in the compatible property (compatible = "nvidia,tegra114-kbc", "nvidia,tegra20-kbc"), so that if Tegra114-specific bugs were found in the future, any device trees would already indicate that they describe Tegra114 HW, so the SW could key off that to enable the workaround. Re-stated: The rules for compatible are: Always include the exact HW name, then optionally include any other HW names it's compatible with.