From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexandre Belloni Subject: Re: [PATCH 4/7] dt-bindings: chosen: Add clocksource and clockevent selection Date: Tue, 10 Sep 2019 17:10:55 +0200 Message-ID: <20190910151055.GX21254@piout.net> References: <1568123236-767-1-git-send-email-claudiu.beznea@microchip.com> <1568123236-767-5-git-send-email-claudiu.beznea@microchip.com> <20190910143231.GB14966@e107533-lin.cambridge.arm.com> <20190910150826.GA18308@e107533-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20190910150826.GA18308@e107533-lin.cambridge.arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+glpr-linux-riscv=m.gmane.org@lists.infradead.org To: Sudeep Holla Cc: tmaimon77@gmail.com, linus.walleij@linaro.org, nsekhar@ti.com, guoren@kernel.org, linux-stm32@st-md-mailman.stormreply.com, heiko@sntech.de, linux-samsung-soc@vger.kernel.org, linux-rockchip@lists.infradead.org, khilman@baylibre.com, Ludovic.Desroches@microchip.com, linux-imx@nxp.com, u.kleine-koenig@pengutronix.de, uclinux-h8-devel@lists.sourceforge.jp, marc.zyngier@arm.com, s.hauer@pengutronix.de, linux-unisoc@lists.infradead.org, khalasa@piap.pl, tglx@linutronix.de, sbranden@broadcom.com, linux-kernel@vger.kernel.org, ralf@linux-mips.org, paul.burton@mips.com, kernel@pengutronix.de, Claudiu.Beznea@microchip.com, mark.rutland@arm.com, jhogan@kernel.org, palmer@sifive.com, eric@anholt.net, thierry.reding@gmail.com, manivannan.sadhasivam@linaro.org, ysato@users.sourceforge.jp, zhang.lyra@gmail.com, daniel.lezcano@linaro.org, jonathanh@nvidia.com, bgolaszewski@baylibre.com List-Id: devicetree@vger.kernel.org On 10/09/2019 16:08:26+0100, Sudeep Holla wrote: > On Tue, Sep 10, 2019 at 02:51:50PM +0000, Claudiu.Beznea@microchip.com wrote: > > > > > > On 10.09.2019 17:32, Sudeep Holla wrote: > > > External E-Mail > > > > > > > > > On Tue, Sep 10, 2019 at 04:47:13PM +0300, Claudiu Beznea wrote: > > >> From: Alexandre Belloni > > >> > > >> Some timer drivers may behave either as clocksource or clockevent > > >> or both. Until now, in case of platforms with multiple hardware > > >> resources of the same type, the drivers were chosing the first > > >> registered hardware resource as clocksource/clockevent and the > > >> next one as clockevent/clocksource. Other were using different > > >> compatibles (one for each functionality, although its about the > > >> same hardware). Add DT bindings to be able to choose the > > >> functionality of a timer. > > >> > > > > > > Is the piece of hardware not capable of serving as both clocksource > > > and clockevent or is it just the platform choice ? > > > > In my case, the hardware is not capable of serving at the same time > > a clocksource device and a clockevent device. > > > > First, I published v1 for a hardware device having this behavior at > > [1] requesting 1st probed hardware device to work as clocksource and > > the 2nd one to work as clockevent. The discussion at [1] ended up with > > the idea of having a mechanism to specify which hardware device behaves > > as clocksource and which one behaves as clockevent. > > > > In that case, why can't we identify capability that with the compatibles > for this timer IP ? > > IOW, I don't like the proposal as it's hardware limitation. > To be clear, bot timers are exactly the same but can't be clocksource and clockevent at the same time. Why would we have different compatibles for the exact same IP? -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com