From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Christophe PLAGNIOL-VILLARD Date: Wed, 29 Apr 2009 21:26:36 +0200 Subject: [U-Boot] U-Boot Timer Qualification In-Reply-To: <20090428174726.C06BB83420E8@gemini.denx.de> References: <20090422204936.GB29252@game.jcrosoft.org> <200904271528.29873.vapier@gentoo.org> <20090428100806.GA4896@localhost.localdomain> <200904280848.14109.vapier@gentoo.org> <20090428151147.GA19683@linux-mips.org> <20090428174726.C06BB83420E8@gemini.denx.de> Message-ID: <20090429192636.GD13941@game.jcrosoft.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 19:47 Tue 28 Apr , Wolfgang Denk wrote: > Dear Ladislav Michl, > > In message <20090428151147.GA19683@linux-mips.org> you wrote: > > > > a lot of changes are entering arm tree, many without any commit message. > > And now we have some special cases which needs some special care for yet > > unclear reason. OMAP3 timer precission was discussed to death and patch > > still didn't went in, because it needs to be verified against some > > document you are claiming is not mandatory. > > Just in case there is any doubt here: > > There is no, and I say *no*, mandatory verification of any timing > precision in U-Boot. > > We all agree that precision is a good thing to have, it it must come > at a reasonable effort, and there is no reason to drive it into > extreme precision. Personnaly I never ask extreme precision I ask to known the precision as the timer is incorrect to known where we go is important > > Clock signals may need an accuracy of 1 or 2% or better - as we may > see character corruption if the baudrate generators are off too far - > but this is usually a hardware issue in the first place. > > System timers (like udelay() etc.) in U-Boot do not need such a level > of accuracy. That does not mean we should intentionally be inaccurate. > > And of course actual testing is good, and documentation of the test > results is even better. > > But: it is not mandatory. Not in U-Boot (and also not in Linux, to the > best of my knowledge). As example when the timer was send by a dev at first and he will send a fix I think it's start to be mandatory to ask him to test it an a the real hard It will avoid to have a new fix again and again which will mean that the timer is never been check in a real use case > > See my previuous posting. I don;t think that a generic test method > that works on all boards would be possible. but a docmument and code to do is good and will hepl the dev evenif we can known and support all boards. This will be improve with patch. Best Regards, J.