From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Babic Date: Thu, 05 Feb 2015 18:52:15 +0100 Subject: [U-Boot] [PATCH] imx: don't clobber reset cause In-Reply-To: <54D3A6D9.8040602@boundarydevices.com> References: <1423086661-5860-1-git-send-email-eric.nelson@boundarydevices.com> <874mr0pbl2.fsf@nbsps.com> <54D3A625.5000101@denx.de> <54D3A6D9.8040602@boundarydevices.com> Message-ID: <54D3ADCF.7010102@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Eric, On 05/02/2015 18:22, Eric Nelson wrote: >>> There is very similar code in 'arch/arm/cpu/armv7/vf610/generic.c'. The >>> write is for a hard power on case where these reason registers are full >>> of weird bogus values (at least on Vybrid; I suspect on iMx). In the >>> case of a non-POR, the register bits are good. However, if you don't >>> clear the status, on the next reset it may have multiple registers bits >>> even though you really want to know the last reason (bit). >>> >>> Another option would be to clear the value and store the 'cause' >>> somewhere for other U-Boot users. Unless you wanted to read this from >>> an OS? I think both files should behave the same, all else equal. >>> >> >> I have assumed (maybe wrong ?) that the reason for the patch is to let >> the OS reading these bits. >> > > In some cases (Windows Embedded), yes. > > In the Linux case, we'll likely pass the value to the kernel through > the kernel command-line, so it's available to userspace. > > I'm not aware of any kernel functionality for this at the moment. > It remains the issue raised by Bill (thanks for that). If the bits are not reset, we can determine the cause only after POR, but not anymore after a warm start. Can you maybe use the IRAM to pass the information to Windows ? Best regards, Stefano Babic -- ===================================================================== DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de =====================================================================