From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760032AbdEOIRX (ORCPT ); Mon, 15 May 2017 04:17:23 -0400 Received: from mail-wr0-f196.google.com ([209.85.128.196]:35400 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759987AbdEOIRP (ORCPT ); Mon, 15 May 2017 04:17:15 -0400 Date: Mon, 15 May 2017 10:17:11 +0200 From: Seraphime Kirkovski To: Mark Brown Cc: linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: [PATCH 1/2] spi: spidev: introduce SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ command Message-ID: <20170515081711.fcvexppqkjzlc7at@macchiaveli> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org christophe.blaess@gmail.com, fred@haapie.com Bcc: Subject: Re: [PATCH 1/2] spi: spidev: introduce SPI_IOC_WR_DEFAULT_MAX_SPEED_HZ command Reply-To: In-Reply-To: <20170514092716.kqx634djffgj32r6@sirena.org.uk> On Sun, May 14, 2017 at 06:27:16PM +0900, Mark Brown wrote: > On Tue, May 09, 2017 at 02:24:00PM +0200, Seraphime Kirkovski wrote: > > > I think, this change is necessary, on the one hand, because there are still > > a lot of longterm[2] supported kernels out there, whose users may be relying on > > SPI_IOC_WR_MAX_SPEED being system-wide and, on the other hand, this > > same command has been exhibiting a different behaviour for 3 years now, > > so its users may break, if 9169051617df7 is reverted in one way or > > another. > > Do we have any evidence that such users exist? I can't guarantee for other such users, but this change did disturb our workflow. We were using this feature to prototype and test hardware/firmware at different speeds. I was thinking this morning that maybe a sysfs interface will be better for setting global settings. Do you prefer ?