From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752225AbcGASkr (ORCPT ); Fri, 1 Jul 2016 14:40:47 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:39274 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751996AbcGASko (ORCPT ); Fri, 1 Jul 2016 14:40:44 -0400 Date: Fri, 1 Jul 2016 11:38:45 -0700 From: Stephen Boyd To: Hoan Tran Cc: Michael Turquette , linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, Duc Dang , lho@apm.com Subject: Re: [PATCH v2] clk: Add fractional scale clock support Message-ID: <20160701183845.GD27880@codeaurora.org> References: <1466458269-460-1-git-send-email-hotran@apm.com> <20160630202358.GC27880@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sorry I replied offlist before. Pressed the wrong key. On 06/30, Hoan Tran wrote: > On Thu, Jun 30, 2016 at 1:23 PM, Stephen Boyd wrote: > > > > How is this different from clk-fractional-divider.c? > > > > This is a driver which clock output is multiplied with a fixed fractional > scale (denominator). > A field inside a register is used to configure the multiplier. > > Example: With fractional scale is 1/8. > Freq_out = Freq_parent * multiplier * (1/8) > > For fractional-divider, there are 2 fields of a register are used which > - A field for numerator > - A field for denominator > Freq_out = Freq_parent * numerator / denominator > Ok so the difference is that the denominator is a fixed value? Perhaps that can be modeled as a clk-multiplier that is used as the only parent of a fixed divider? Or we can add a flag to the clk-fractional-divider code to handle this minor difference. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project