From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: [PATCH v2] drm/i915: Run DDC buses at 50 kbps Date: Thu, 22 Mar 2012 21:50:23 +0100 Message-ID: <20120322205023.GC21393@phenom.ffwll.local> References: <201203211429.48066.jdelvare@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wg0-f43.google.com (mail-wg0-f43.google.com [74.125.82.43]) by gabe.freedesktop.org (Postfix) with ESMTP id 8A96D9E709 for ; Thu, 22 Mar 2012 13:49:40 -0700 (PDT) Received: by wgbdr12 with SMTP id dr12so1357225wgb.12 for ; Thu, 22 Mar 2012 13:49:39 -0700 (PDT) In-Reply-To: <201203211429.48066.jdelvare@suse.de> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org To: Jean Delvare Cc: dri-devel@lists.freedesktop.org, Eugeni Dodonov List-Id: dri-devel@lists.freedesktop.org On Wed, Mar 21, 2012 at 02:29:47PM +0100, Jean Delvare wrote: > A udelay value of 20 leads to an I2C bus running at only 25 kbps. I2C > devices can typically operate faster than this, 50 kbps should be fine > for all devices (and compliant devices can always stretch the clock if > needed.) > > FWIW, the vast majority of framebuffer drivers set udelay to 10 > already. So set it to 10 in DRM drivers too, this will make EDID block > reads faster. We might even lower the udelay value later if no problem > is reported. > > Signed-off-by: Jean Delvare > Acked-by: Eugeni Dodonov > Cc: Dave Airlie > Cc: Keith Packard Fyi this already got merged int Dave's tree (the unsplit version) as: commit 1849ecb22fb3b5d57b65e7369a3957adf9f26f39 Author: Jean Delvare Date: Sat Jan 28 11:07:09 2012 +0100 drm/kms: Make i2c buses faster Cheers, Daniel > --- > Changes since v1: > * Split per driver to make merging easier. > * Make the subject line more accurate. > > drivers/gpu/drm/i915/intel_i2c.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- linux-3.4-rc0.orig/drivers/gpu/drm/i915/intel_i2c.c 2012-03-21 13:43:33.750915151 +0100 > +++ linux-3.4-rc0/drivers/gpu/drm/i915/intel_i2c.c 2012-03-21 13:44:05.923915628 +0100 > @@ -37,7 +37,7 @@ > > /* Intel GPIO access functions */ > > -#define I2C_RISEFALL_TIME 20 > +#define I2C_RISEFALL_TIME 10 > > static inline struct intel_gmbus * > to_intel_gmbus(struct i2c_adapter *i2c) > > -- > Jean Delvare > Suse L3 > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48