From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH v2 1/3] clocksource: tegra: Add nvidia,tegra30-timer compat Date: Wed, 05 Feb 2014 13:17:09 -0700 Message-ID: <52F29C45.9020206@wwwdotorg.org> References: <1391473055-3158-1-git-send-email-achew@nvidia.com> <1391473055-3158-2-git-send-email-achew@nvidia.com> <52F2996B.4080005@wwwdotorg.org> <643E69AA4436674C8F39DCC2C05F763863199859AC@HQMAIL03.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <643E69AA4436674C8F39DCC2C05F763863199859AC@HQMAIL03.nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Andrew Chew , "daniel.lezcano@linaro.org" , "tglx@linutronix.de" , "thierry.reding@gmail.com" , "rob@landley.net" , "grant.likely@linaro.org" , "robh+dt@kernel.org" , "abrestic@chromium.org" , "dgreid@chromium.org" , "katierh@chromium.org" Cc: "linux-kernel@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-watchdog@vger.kernel.org" , "linux-doc@vger.kernel.org" List-Id: linux-tegra@vger.kernel.org On 02/05/2014 01:06 PM, Andrew Chew wrote: >> On 02/03/2014 05:17 PM, Andrew Chew wrote: >>> There are some differences between tegra20's timer registers and >>> tegra30's (and later). For example, tegra30 has more timers. In >>> addition, watchdogs are not present in tegra20. >>> >>> Add this compatibility string in order to be able to distinguish >>> whether the additional timers and watchdogs are there or not. >> >>> diff --git a/drivers/clocksource/tegra20_timer.c >>> b/drivers/clocksource/tegra20_timer.c >> >>> CLOCKSOURCE_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer", >>> tegra20_init_timer); >>> +CLOCKSOURCE_OF_DECLARE(tegra30_timer, "nvidia,tegra30-timer", >>> +tegra20_init_timer); >> >> Thinking about this more, nothing in this driver actually cares about >> Tegra20 vs. Tegra30+, since the timer that's used is present in all chips. >> Hence, this patch isn't needed. > > Don't I need to add nvidia,tegra30-timer so that the tegra WDT driver > can match against it? It would be weird to have the tegra WDT driver > bind against nvidia,tegra20-timer when the tegra WDT driver as it is won't > work at all on tegra20. The DT files need to contain all of: * The specific SoC (this is already present) * nvidia,tegra30-timer for SoCs >= Tegra30 (this is missing) * nvidia,tegra20-timer for all SoCs (this is already present) However, since all DTs will contain nvidia,tegra20-timer, since all HW is backwards-compatible IIUC, any code that only cares about the parts that have existed since Tegra20 only need match against the Tegra20 compatible value.