From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 20 Jun 2016 14:41:57 +0900 From: Andi Shyti To: Tomasz Figa Cc: Andi Shyti , Chanwoo Choi , Sylwester Nawrocki , Michael Turquette , Stephen Boyd , Kukjin Kim , Krzysztof Kozlowski , "linux-samsung-soc@vger.kernel.org" , linux-clk@vger.kernel.org, linux-arm-kernel , linux-kernel , Jaehoon Chung , Andi Shyti Subject: Re: [PATCH] clk: samsung: exynos5433: use clock_ignore_unused flag for SPI3 related clocks Message-id: <20160620054157.GA6498@samsunx.samsung> References: <1466151362-2881-1-git-send-email-andi.shyti@samsung.com> <20160619055921.GA424@jack.zhora.eu> MIME-version: 1.0 Content-type: text/plain; charset=us-ascii In-reply-to: List-ID: Hi Tomasz, > >> > The SPI 3 bus uses two clocks, a bus clock and an input clock. > >> > Do not disable the clocks when unused in order to allow access to > >> > the SPI 3 device. > >> > >> If unused, why would access to SPI 3 device needed? > > > > because next I will submit a small driver which uses the SPI3. > > Actually in the exynos5433 boards all the SPI are used but not all > > the drivers are ported to mainline. > > Then shouldn't the driver request the clocks and enable them? Or I'm > missing something obvious? :) the reason is that... [ from the patch ] > GATE(CLK_SCLK_IOCLK_SPI3, "sclk_ioclk_spi3", "ioclk_spi3_clk_in", > - ENABLE_SCLK_PERIC, 20, CLK_SET_RATE_PARENT, 0), > + ENABLE_SCLK_PERIC, 20, > + CLK_IGNORE_UNUSED | CLK_SET_RATE_PARENT, 0), ... the sclk_ioclk_spi3 is new in exynos5433 and there is no implementation for enabling/disabling that particular clock... > GATE(CLK_SCLK_SPI3, "sclk_spi3", "sclk_spi3_peric", ENABLE_SCLK_PERIC, > - 18, CLK_SET_RATE_PARENT, 0), > + 18, CLK_IGNORE_UNUSED | CLK_SET_RATE_PARENT, 0), ... while in this case your question makes sense, but it depends on which clock the device (s3c64xx) is requesting (from the DTS). In any case, I kept it consistent with the SPI1, which falls in the same case, as in mainline we don't have any DTS for exynos5433 (yet!). Thanks, Andi