From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [PATCH v3 2/7] bindings: spi-samsung: document the clocks and the clock-name property To: Rob Herring , Andi Shyti References: <1468317736-18841-1-git-send-email-andi.shyti@samsung.com> <1468317736-18841-3-git-send-email-andi.shyti@samsung.com> <20160716203044.GA13087@rob-hp-laptop> Cc: Mark Rutland , Kukjin Kim , Krzysztof Kozlowski , Mark Brown , Tomasz Figa , Michael Turquette , Stephen Boyd , Chanwoo Choi , Jaehoon Chung , linux-clk@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-spi@vger.kernel.org, Andi Shyti From: Sylwester Nawrocki Message-id: <578CAFAF.9060704@samsung.com> Date: Mon, 18 Jul 2016 12:30:07 +0200 MIME-version: 1.0 In-reply-to: <20160716203044.GA13087@rob-hp-laptop> Content-type: text/plain; charset=windows-1252 List-ID: On 07/16/2016 10:30 PM, Rob Herring wrote: >> diff --git a/Documentation/devicetree/bindings/spi/spi-samsung.txt >> b/Documentation/devicetree/bindings/spi/spi-samsung.txt >> > index 57d5539..f45c6eb 100644 >> > --- a/Documentation/devicetree/bindings/spi/spi-samsung.txt >> > +++ b/Documentation/devicetree/bindings/spi/spi-samsung.txt >> > @@ -24,6 +24,15 @@ Required SoC Specific Properties: >> > - dma-names: Names for the dma channels. There must be at least one channel >> > named "tx" for transmit and named "rx" for receive. >> > >> > +- clocks: specifies the clock IDs provided to the SPI controller; they are >> > + required for interacting with the controller itself, for synchronizing the bus >> > + and as I/O clock (the latter is required by exynos5433 and exynos7). >> > + >> > +- clock-names: string names of the clocks in the 'clocks' property; for all the >> > + the devices the names must be "spi", "spi_busclkN" (where N is determined by >> > + "samsung,spi-src-clk"), while Exynos5433 should specify a third clock > > This sounds like you are describing the configuration of the clocks, not > the connections. The binding here should list clocks for all possible > vaules of N as those are all the input clocks to the block. > >> > + "spi_ioclk" for the I/O clock. I agree we should list all possible spi_busclkN, I must admit I might have introduced some confusion by suggesting wording for clock-names similar to the above while discussing those things internally. Afterwards I came to a similar conclusion all possible input clocks should be listed These will differ depending on the compatible. I checked in documentation of most of related SoCs and for "samsung,s3c6410-spi" or older compatibles possible N is 0..2 (PCLK, USBCLK, PLL clock), for "samsung,s5pv210-spi" and newer possible N is 0 (SCLK_SPI). It's important to have all the input clocks listed so we have a list of parent clocks to the SPI controller's internal clocks, should we ever decide to model them with the clk API. -- Thanks, Sylwester