From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756291Ab0IHQAj (ORCPT ); Wed, 8 Sep 2010 12:00:39 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:49172 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755790Ab0IHQAh (ORCPT ); Wed, 8 Sep 2010 12:00:37 -0400 Date: Wed, 8 Sep 2010 10:00:34 -0600 From: Grant Likely To: Jassi Brar Cc: Mark Brown , David Brownell , Jassi Brar , spi-devel-general@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] spi/spi_s3c64xx: Increase dead reckoning time in wait_for_xfer() Message-ID: <20100908160034.GB3686@angua.secretlab.ca> References: <1283873872-8633-1-git-send-email-broonie@opensource.wolfsonmicro.com> <1283873872-8633-2-git-send-email-broonie@opensource.wolfsonmicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 08, 2010 at 10:44:26AM +0900, Jassi Brar wrote: > On Wed, Sep 8, 2010 at 12:37 AM, Mark Brown > wrote: > > For small transfers at high speeds the expected transfer time can easily > > be well under 1ms, causing the delay in wait_for_xfer() to be only the > > dead reckoning fudge factor of 5ms currently included. Experiments on > > some of my systems shows that this is marginal for some transfers so > > double it to 10ms. > > > > Signed-off-by: Mark Brown > > --- > >  drivers/spi/spi_s3c64xx.c |    2 +- > >  1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/spi/spi_s3c64xx.c b/drivers/spi/spi_s3c64xx.c > > index 03b28e4..4abb441 100644 > > --- a/drivers/spi/spi_s3c64xx.c > > +++ b/drivers/spi/spi_s3c64xx.c > > @@ -326,7 +326,7 @@ static int wait_for_xfer(struct s3c64xx_spi_driver_data *sdd, > > > >        /* millisecs to xfer 'len' bytes @ 'cur_speed' */ > >        ms = xfer->len * 8 * 1000 / sdd->cur_speed; > > -       ms += 5; /* some tolerance */ > > +       ms += 10; /* some tolerance */ > > > >        if (dma_mode) { > >                val = msecs_to_jiffies(ms) + 10; > > Acked-by: Jassi Brar Applied, thanks. g.