From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:17746 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754481AbaCKNio (ORCPT ); Tue, 11 Mar 2014 09:38:44 -0400 Message-id: <531F11DD.5040300@samsung.com> Date: Tue, 11 Mar 2014 14:38:37 +0100 From: Sylwester Nawrocki MIME-version: 1.0 To: Laurent Pinchart Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, robh+dt@kernel.org, mark.rutland@arm.com, galak@codeaurora.org, kyungmin.park@samsung.com, kgene.kim@samsung.com, a.hajda@samsung.com Subject: Re: [PATCH v6 03/10] Documentation: devicetree: Update Samsung FIMC DT binding References: <1394122819-9582-1-git-send-email-s.nawrocki@samsung.com> <1394122819-9582-4-git-send-email-s.nawrocki@samsung.com> <1608087.RUCeTiNcRR@avalon> In-reply-to: <1608087.RUCeTiNcRR@avalon> Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Laurent, Thanks for your review. On 11/03/14 13:30, Laurent Pinchart wrote: [...] >> --- >> .../devicetree/bindings/media/samsung-fimc.txt | 34 ++++++++++++----- >> 1 file changed, 26 insertions(+), 8 deletions(-) >> >> diff --git a/Documentation/devicetree/bindings/media/samsung-fimc.txt >> b/Documentation/devicetree/bindings/media/samsung-fimc.txt index >> 96312f6..dbd4020 100644 >> --- a/Documentation/devicetree/bindings/media/samsung-fimc.txt >> +++ b/Documentation/devicetree/bindings/media/samsung-fimc.txt >> @@ -32,6 +32,21 @@ way around. >> >> The 'camera' node must include at least one 'fimc' child node. >> >> +Optional properties: >> + >> +- #clock-cells: from the common clock bindings >> (../clock/clock-bindings.txt), >> + must be 1. A clock provider is associated with the 'camera' node and it >> should >> + be referenced by external sensors that use clocks provided by the SoC on >> + CAM_*_CLKOUT pins. The clock specifier cell stores an index of a clock. >> + The indices are 0, 1 for CAM_A_CLKOUT, CAM_B_CLKOUT clocks respectively. >> + >> +- clock-output-names: from the common clock bindings, should contain names >> of >> + clocks registered by the camera subsystem corresponding to CAM_A_CLKOUT, >> + CAM_B_CLKOUT output clocks respectively. > > Wouldn't it be better to document the "cam_mclk_a" and "cam_mclk_b" names > explicitly ? Or do you expect different names to be used in different DT files > ? And as they correspond to the CAM_A_CLKOUT and CAM_B_CLKOUT pins, shouldn't > they be named "cam_a_clkout" and "cam_b_clkout" ? Basically I could use fixed names for these clocks, I just wanted to keep a possibility to override them in dts to avoid any possible clock name collisions, rather than keep a list of different names per SoC in the driver. Right now fixed names could also be used for all SoCs I'm aware of, nevertheless I would prefer to keep the clock-output-names property. "cam_a_clkout", "cam_b_clkout" may be indeed better names, I'll change that. >> +Note: #clock-cells and clock-output-names are mandatory properties if >> external >> +image sensor devices reference 'camera' device node as a clock provider. >> + > > What's the reason not to make them always mandatory ? Backward compatibility > only ? If so wouldn't it make sense to document the properties as mandatory > from now on, and treating them as optional in the driver for backward > compatibility ? Yes, it's for backwards compatibility only. It may be a good idea to just document them as required, since this is how the device is expected to be described in DT from now. I'll just make these a required properties, the driver already handles them as optional. >> 'fimc' device nodes >> ------------------- >> >> @@ -97,8 +112,8 @@ Image sensor nodes >> The sensor device nodes should be added to their control bus controller >> (e.g. I2C0) nodes and linked to a port node in the csis or the >> parallel-ports node, using the common video interfaces bindings, defined in >> video-interfaces.txt. >> -The implementation of this bindings requires clock-frequency property to be >> -present in the sensor device nodes. >> +An optional clock-frequency property needs to be present in the sensor >> device >> +nodes. Default value when this property is not present is 24 MHz. > > This bothers me. Having the FIMC driver read the clock-frequence property from > the sensor DT nodes feels like a layering violation. Shouldn't the sensor > drivers call clk_set_rate() explicitly instead ? It is supposed to do so, after this whole patch series. So the camera controller driver will not need such properties. What do you think about removing this sentence altogether ? >> Example: >> >> @@ -114,7 +129,7 @@ Example: >> vddio-supply = <...>; >> >> clock-frequency = <24000000>; >> - clocks = <...>; >> + clocks = <&camera 1>; >> clock-names = "mclk"; >> >> port { >> @@ -135,7 +150,7 @@ Example: >> vddio-supply = <...>; >> >> clock-frequency = <24000000>; >> - clocks = <...>; >> + clocks = <&camera 0>; >> clock-names = "mclk"; >> >> port { >> @@ -149,12 +164,15 @@ Example: >> >> camera { >> compatible = "samsung,fimc", "simple-bus"; >> - #address-cells = <1>; >> - #size-cells = <1>; >> - status = "okay"; >> - >> + clocks = <&clock 132>, <&clock 133>; >> + clock-names = "sclk_cam0", "sclk_cam1"; > > The documentation mentions that clock-names must contain "sclk_cam0", > "sclk_cam1", "pxl_async0", "pxl_async1". Are the last two optional ? If so I > think you should clarify the description of the clock-names property. This can > be done in a separate patch. "pxl_async0", "pxl_async1" are mandatory, I'll add them also into this example dts. >> + #clock-cells = <1>; >> + clock-output-names = "cam_mclk_a", "cam_mclk_b"; >> pinctrl-names = "default"; >> pinctrl-0 = <&cam_port_a_clk_active>; >> + status = "okay"; >> + #address-cells = <1>; >> + #size-cells = <1>; >> >> /* parallel camera ports */ >> parallel-ports { -- Regards, Sylwester