Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757523AbcJNOVA (ORCPT ); Fri, 14 Oct 2016 10:21:00 -0400 Received: from muru.com ([72.249.23.125]:44220 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752554AbcJNOUw (ORCPT ); Fri, 14 Oct 2016 10:20:52 -0400 Date: Fri, 14 Oct 2016 07:20:47 -0700 From: Tony Lindgren To: Jacek Anaszewski Cc: Matt Ranostay , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , Matt Ranostay , Rob Herring , Mark Rutland Subject: Re: [PATCH] leds: leds-pca963x: workaround group blink scaling issue Message-ID: <20161014142047.imm4idfetphlp5od@atomide.com> References: <1476364572-26849-1-git-send-email-matt@ranostay.consulting> <924a896d-b3f2-5fed-62ba-a731e79e1567@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <924a896d-b3f2-5fed-62ba-a731e79e1567@samsung.com> User-Agent: Mutt/1.6.2-neo (2016-07-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1173 Lines: 31 * Jacek Anaszewski [161013 23:37]: > On 10/13/2016 04:20 PM, Matt Ranostay wrote: > > On Thu, Oct 13, 2016 at 4:05 PM, Jacek Anaszewski > > wrote: > > > Why DT property? Is it somehow dependent on the board configuration? > > > How this period-scale value is calculated? Is it inferred empirically? > > > > > > > We empirically discovered and verified this with an logic analyzer on > > multiple batches of this part. > > Reason for the DT entry is we aren't 100% sure that it is always going > > to be the same with different board revs. > > > > Could be that parts clock acts differently with supply voltage. This > > has been calculated by setting it an expected value, and measuring the > > actual result with the logic analyzer. > > I'd like to have DT maintainer's ack for this. > > Cc Rob and Mark. How about do this based on the compatible property instead? If there are multiple manufacturers for this part and only a certain parts have this issue we should have multiple compatible properties. Then if it turns out all of them need this scaling there's no need to update the binding. Regards, Tony