Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754891AbdFWTAQ (ORCPT ); Fri, 23 Jun 2017 15:00:16 -0400 Received: from mo4-p00-ob.smtp.rzone.de ([81.169.146.163]:18924 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754327AbdFWTAO (ORCPT ); Fri, 23 Jun 2017 15:00:14 -0400 X-RZG-AUTH: :JGIXVUS7cutRB/49FwqZ7WcecEarQROEYabkiUo6mSAGQ+qKID8yPJCLgHE= X-RZG-CLASS-ID: mo00 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCH v1 1/6] DT bindings: add bindings for ov965x camera module From: "H. Nikolaus Schaller" In-Reply-To: <3f0dcd4f-92ef-a79d-b00b-1f348a201bd2@ti.com> Date: Fri, 23 Jun 2017 20:59:28 +0200 Cc: Mark Rutland , devicetree , Benjamin Gaignard , Discussions about the Letux Kernel , Alexandre Torgue , LKML , Hans Verkuil , Rob Herring , Maxime Coquelin , Yannick Fertre , Sylwester Nawrocki , Mauro Carvalho Chehab , Guennadi Liakhovetski , linux-arm-kernel , linux-media@vger.kernel.org Message-Id: <74EE8B20-84A2-4579-ACBE-32E55CECE1C5@goldelico.com> References: <1498143942-12682-1-git-send-email-hugues.fruchet@st.com> <3E7B1344-ECE6-4CCC-9E9D-7521BB566CDE@goldelico.com> <13144955.Kq5qljPvgI@avalon> <24C976BF-52FD-4509-BCE4-9AE41B335482@goldelico.com> <88d0e8ea-74e4-6845-4e0d-8cd0f3a054be@suse.de> <05CBF9B8-2297-447B-860D-A89126B46FC9@goldelico.com> <3f0dcd4f-92ef-a79d-b00b-1f348a201bd2@ti.com> To: Suman Anna , =?utf-8?Q?Andreas_F=C3=A4rber?= , Hugues Fruchet , Laurent Pinchart X-Mailer: Apple Mail (2.3124) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id v5NJ0W3g021712 Content-Length: 2050 Lines: 57 Hi Suman, > Am 23.06.2017 um 20:05 schrieb Suman Anna : > >>>> >>>> Or does it just mean that it defines the property name? >>> >>> Please read the documentation link I sent - it's in the very bottom and >>> should have an example. >> >> I have seen it but it does not give me a good clue how to translate that into >> correct omap3isp node setup in a specific DT. Rather it raises more questions. >> Maybe because I don't understand completely what it is talking about. >> >> The fundamental question is if this "assigned-clock-rates" is already >> handled by ov965x->clk = devm_clk_get(&client->dev, NULL); ? >> >> Or should we define that for the omap3isp node? >> >> Then of course we need no new code and just use the right property names. >> And N900, N9 camera DTs should be updated. > > Look up of_clk_set_defaults() function in drivers/clk/clk-conf.c. This > function gets invoked usually during clock registration, and also gets > called in platform_drv_probe(), so the parents and clocks do get > configured before your driver gets probed. So, this provides a default > configuration if these properties are supplied (in either clock nodes or > actual device nodes), and if your driver needs to change the rates at > runtime, then you would have to do that in the driver itself. Ok, now I understand. Thanks! Quite hidden, but nice feature. I would never have thought that it exists. Especially as there are no examples around omap3isp cameras... And an fgrep assigned-clock-rates shows not many use cases outside CPU/SoC include files. But interestingly arch/arm/boot/dts/at91sam9g25ek.dts uses it for an ovti,ov2640 camera... So it seems that we just have to write: ov9655@30 { compatible = "ovti,ov9655"; reg = <0x30>; clocks = <&isp 0>; /* cam_clka */ assigned-clocks = <&isp 0>; assigned-clock-rates = <24000000>; }; instead of introducing a new clock-frequency property and code to handle it. Or do I misinterpret what "parents" and "clocks" are in this context? BR and thanks, Nikolaus