From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755270AbaEVMZ5 (ORCPT ); Thu, 22 May 2014 08:25:57 -0400 Received: from mailout3.w1.samsung.com ([210.118.77.13]:61106 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755246AbaEVMZy (ORCPT ); Thu, 22 May 2014 08:25:54 -0400 X-AuditID: cbfec7f5-b7f626d000004b39-9a-537deccf4e9a Message-id: <537DECCE.8000301@samsung.com> Date: Thu, 22 May 2014 14:25:50 +0200 From: Sylwester Nawrocki User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-version: 1.0 To: Tomasz Figa , Tushar Behera Cc: linux-samsung-soc , lkml , devicetree , "linux-arm-kernel@lists.infradead.org" , Mike Turquette , Kukjin Kim , Rob Herring , Mark Rutland , Marek Szyprowski , Pankaj Dubey , Rahul Sharma , Mark Brown , Tomasz Figa Subject: Re: [PATCH 3/4] clk: samsung: Add driver to control CLKOUT line on Exynos SoCs References: <1400604211-9447-1-git-send-email-t.figa@samsung.com> <1400604211-9447-4-git-send-email-t.figa@samsung.com> <537D8788.8030904@linaro.org> <537DD2C0.4060802@samsung.com> <537DE714.1090407@samsung.com> In-reply-to: <537DE714.1090407@samsung.com> Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrHLMWRmVeSWpSXmKPExsVy+t/xa7rn39QGGzx4rGYx9eETNov5R86x WvQuuMpmsenxNVaLy7vmsFnMOL+PyWLtkbvsFkuvX2SyeDrhIpvFoq1f2C2mLDrMatG69wi7 xfoZr1ksVu36w2jR/ncvmwO/x5p5axg9ds66y+6xaVUnm8eda3vYPDYvqffo27KK0ePzJrkA 9igum5TUnMyy1CJ9uwSujJMTDAr+8FW8ebSfrYFxLXcXIyeHhICJxN95d5khbDGJC/fWs3Ux cnEICSxllPg/dRkThPOJUeL9pAWsXYwcHLwCWhIbPxaCNLAIqEpcX/ufCcRmEzCU6D3axwhS IioQIfH4ghBImFdAUOLH5HssILaIgJ/EiT+HGEFGMgvsY5HY+Hk72GJhgUiJWxefs0DsWsAk cbJvFztIglNAW6J9/2uwbmYBdYlJ8xYxQ9jyEpvXvGWewCgwC8mSWUjKZiEpW8DIvIpRNLU0 uaA4KT3XSK84Mbe4NC9dLzk/dxMjJI6+7mBceszqEKMAB6MSD29HVm2wEGtiWXFl7iFGCQ5m JRFexydAId6UxMqq1KL8+KLSnNTiQ4xMHJxSDYwJrvpem5obbB7ksa6YfemqRKDaxEPB3Iab fp2ViuLnOLW80nL3Tm6+bXuqpxYHnXkfaN2adjYyvXtqb3jGDbbmp8kupQ+UIltfLWNf82hh vaS+id8Oh8y4ucvfFIZdN5d6pyV1WOPY2luz3J3adk3a/Ct++3/lYEdtpqvaiq/bxGLr5hyf 6qTEUpyRaKjFXFScCAC/W/RIgQIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/05/14 14:01, Tomasz Figa wrote: >>>> >>> [ ... ] >>>> >>> >>>>> >>>> + clkout->clk_table[0] = clk_register_composite(NULL, "clkout", >>>>> >>>> + parent_names, parent_count, &clkout->mux.hw, >>>>> >>>> + &clk_mux_ops, NULL, NULL, &clkout->gate.hw, >>>>> >>>> + &clk_gate_ops, CLK_SET_RATE_PARENT >>>>> >>>> + | CLK_SET_RATE_NO_REPARENT); >>>> >>> >>>> >>> Would you please remove CLK_SET_RATE_NO_REPARENT flag from here? Let me >>>> >>> know if you have reservations against this. >>> >> >>> >> The problem with clock reparenting is that there are certain parent >>> >> clocks of CLKOUT, rate of which changes at runtime, e.g. clocks derived >>> >> from APLL or bus clocks, which can be reconfigured by cpufreq or devfreq. >>> >> >> > >> > +CC: Sylwester Nawrocki >> > >> > Okay. But in cases where there is only 1 valid parent clock provided >> > through DT (at the moment for Exynos5250/Exynos5420), would it be safe >> > to set that clock as the parent of CLKOUT? > > This is not something to rely on. I have simply omitted remaining CLKOUT > parents on Exynos 5 SoCs, as I don't have any board with them on which I > could test this. Eventually they will be added. > >> > Otherwise, this clock is >> > not usable ATM. > > On many boards it is already configured properly by the bootloader. > Although I don't see any reason why you couldn't reparent it in > (board-specific) sound card driver right now. This would require passing the parent's clock specifier in 'clocks' property of the sound card device node, which I assume is not something we're generally expected to do in mainline. Although some drivers happen to be doing it already I think that's a bad example. It sounds like an abuse of the current clock bindings. -- Regards, Sylwester