From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shin-ichiro KAWASAKI Date: Mon, 01 Jun 2009 22:37:47 +0000 Subject: Re: [PATCH] clocksource: SuperH TMU Timer driver Message-Id: <4A24583B.2070604@juno.dti.ne.jp> List-Id: References: <20090501065100.8800.99808.sendpatchset@rx1.opensource.se> In-Reply-To: <20090501065100.8800.99808.sendpatchset@rx1.opensource.se> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org Paul Mundt wrote: > On Mon, Jun 01, 2009 at 07:50:40PM +0900, Magnus Damm wrote: >> 2009/5/30 Shin-ichiro KAWASAKI : >>> I made some investigation, and found that the warnings are printed >>> after zero value is set to TCOR. ?I checked SH7785 hardware manual, >>> but could not find any description what happens when zero value set >>> to TCOR. >> Thanks for investigating. I read a few SH manuals before converting >> the old driver, but I couldn't find any description of zero value. >> Same as you. >> >> The idea with zero value TCOR comes from the old driver. It may be >> there for some historical reason, or it may just be plain wrong. I've >> sometimes seen interrupt bursts with the old tmu driver which may be >> related. >> > It was mostly there just because it worked and seemed like a reasonable > thing to do, and because no one had any better ideas on what to do in > that situation. But yes, technically the behaviour is undefined, and so > finding something slightly more precise is a good idea. Thank you for your explanations, Magnus, Paul! It has got clearer for me. I guess there are two solutions. i) Add one-shot timer feature to qemu-sh's TMU emulation. (Even though this feature is not documented.) ii) Modify sh-linux TMU driver not to set zero value to TCOR. (A status will be added to sh_tmu_priv.) I'll consider on both of them, but that will take a week or so. Any help from others will be appreciated. Regards, Shin-ichiro KAWASAKI