From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756770AbaDKJYP (ORCPT ); Fri, 11 Apr 2014 05:24:15 -0400 Received: from top.free-electrons.com ([176.31.233.9]:44622 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756580AbaDKJWB (ORCPT ); Fri, 11 Apr 2014 05:22:01 -0400 Date: Fri, 11 Apr 2014 11:21:57 +0200 From: Antoine =?iso-8859-1?Q?T=E9nart?= To: Jisheng Zhang Cc: "sebastian.hesselbarth@gmail.com" , "linus.walleij@linaro.org" , "alexandre.belloni@free-electrons.com" , Jimmy Xu , "linux-arm-kernel@lists.infradead.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH RESEND 2/5] pinctrl: berlin: add a pinctrl driver for Marvell Berlin SoCs Message-ID: <20140411092157.GD20147@kwain> References: <1397135274-10764-1-git-send-email-antoine.tenart@free-electrons.com> <1397135274-10764-3-git-send-email-antoine.tenart@free-electrons.com> <20140411144431.04fb148d@xhacker> <20140411081839.GB20147@kwain> <20140411162716.74e739e1@xhacker> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140411162716.74e739e1@xhacker> 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 Jisheng, On Fri, Apr 11, 2014 at 04:27:16PM +0800, Jisheng Zhang wrote: > Hi Antoine, > > On Fri, 11 Apr 2014 01:18:39 -0700 > Antoine Ténart wrote: > > > Hi Jisheng, > > > > On Fri, Apr 11, 2014 at 02:44:31PM +0800, Jisheng Zhang wrote: > > > On Thu, 10 Apr 2014 06:07:51 -0700 > > > Antoine Ténart wrote: > > > > > > ... > > > > +static int berlin_pinmux_enable(struct pinctrl_dev *pctrl_dev, > > > > + unsigned function, > > > > + unsigned group) > > > > +{ > > > > + struct berlin_pinctrl *pctrl = > > > > pinctrl_dev_get_drvdata(pctrl_dev); > > > > + struct berlin_pinctrl_group *group_desc = pctrl->groups + group; > > > > + struct berlin_pinctrl_function *function_desc = > > > > + pctrl->functions + function; > > > > + unsigned long flags; > > > > + u32 regval; > > > > + > > > > + spin_lock_irqsave(&pctrl->lock, flags); > > > > + > > > > + regval = readl(group_desc->reg); > > > > + regval &= group_desc->mask; > > > > + regval |= function_desc->muxval << group_desc->lsb; > > > > + writel(regval, group_desc->reg); > > > > > > Could we use relaxed version instead? > > > > We could, but this is not a performance issue here at all, so I guess we can > > keep writel(). > > Yes it's not a performance issue here but an issue for the system which is doing > PL310 L2 cache maintenance. If pinmux operation hold the l2x0_lock due to writel() > the important video/audio process which is cleaning PL310 cache must wait, thus > cause jitter. So I'd like relaxed version if we can. Then I don't need to add this > patch to mainline kernel when we upgrade internal tree. I'm not sure I got that. As I understand it, you will need to play video/audio *while* configuring the pinmux. But the pinmuxing configuration is done at boot time, and I don't think a video/audio is being played then. So I'm not certain a jitter will appear. What do you think ? Antoine -- Antoine Ténart, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com