Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757887AbbEVRms (ORCPT ); Fri, 22 May 2015 13:42:48 -0400 Received: from mail-qg0-f50.google.com ([209.85.192.50]:32874 "EHLO mail-qg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757504AbbEVRmq (ORCPT ); Fri, 22 May 2015 13:42:46 -0400 MIME-Version: 1.0 In-Reply-To: <1432252663-31318-7-git-send-email-ezequiel.garcia@imgtec.com> References: <1432252663-31318-1-git-send-email-ezequiel.garcia@imgtec.com> <1432252663-31318-7-git-send-email-ezequiel.garcia@imgtec.com> Date: Fri, 22 May 2015 10:42:45 -0700 X-Google-Sender-Auth: lxtg_Q3TcCwqAESmrfLpQXYDD9o Message-ID: Subject: Re: [PATCH 6/9] clk: pistachio: Propagate rate changes in the MIPS PLL clock sub-tree From: Andrew Bresticker To: Ezequiel Garcia Cc: Linux-MIPS , "linux-kernel@vger.kernel.org" , Mike Turquette , Stephen Boyd , James Hartley , Govindraj Raja , Damien Horsley , Kevin Cernekee , James Hogan Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1113 Lines: 21 On Thu, May 21, 2015 at 4:57 PM, Ezequiel Garcia wrote: > This commit passes CLK_SET_RATE_PARENT to the "mips_div", > "mips_internal_div", and "mips_pll_mux" clocks. This flag is needed for the > "mips" clock to propagate rate changes up to the "mips_pll" root clock. > > Signed-off-by: Govindraj Raja > Signed-off-by: Ezequiel Garcia IIRC the clk core will prefer changing a downstream divider over propagating the rate change up another level. So, for example, if MIPS_PLL is initially 400Mhz and we request a MIPS rate of 200Mhz, we'll change the first intermediate divider to /2 rather than propagate the rate change up to MIPS_PLL. Wouldn't it be more power-efficient to set the MIPS_PLL directly to the requested rate rather than using external dividers to divide it down? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/