From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Caudle Date: Tue, 25 Aug 2009 08:49:51 -0400 Subject: [U-Boot] RTC value corruption on QIL-A9G20 startup In-Reply-To: <20090825083729.GA10327@pc-ras4041.res.insa> References: <20090825083729.GA10327@pc-ras4041.res.insa> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Albin, On Tue, Aug 25, 2009 at 4:37 AM, Albin Tonnerre wrote: > I guess you mean SBC35-A9G20? I actually tried it with the patches for both boards (TNY & SBC35) and saw the same result. > > Everything seems to work properly except the RTC. ?They use the same M41T94 > > part and the CS is the same on both boards (PA3). ?I can set the RTC using the > > "date" command and read back the value okay. ?However, when I power cycle the > > board, the value is getting corrupted at startup due to some erroneous SPI > > write. > > > > I don't believe the code you submitted is causing this problem because the RTC > > is getting corrupted even if I compile out SPI and RTC support completely. ?I > > was just wondering if you have seen this problem on your board? > > Yes, I also experience this issue. Well, at least I'm not the only one. :) > > > I probed the > > CS line with an oscilloscope and I am definitely seeing it go low on U-Boot > > startup for a short time, but the clock line seems to be floating. ?I believe > > the activation of the CS at startup is causing junk data to be written to the > > RTC, which is corrupting it. ?Any idea why this might be happenning? > > Currently, I don't really have any idea. Besides, it's going to be hard for me > to debug this, as I don't have an oscilloscope at hand. Would you please try to > run u-boot within a debugger to see where exactly the CS line is driven low? I upgraded to the "next" branch and the problem seems to have gone away. I will continue to investigate the root cause of this and let you know what I find. Regards, Stephen