Hello Teerth, On Fri, 23 Apr 2010, Reddy, Teerth wrote: > From: Teerth Reddy <teerth@xxxxxx> > > This patch has the workaround for errata 1.176. > In some cases, user is not able to access DDR memory after > warm-reset.This situation occurs while the warm-reset > happens during a read access to DDR memory. In that > particular conditions, DDR memory does not respond to a > corrupted read command due to the warm reset occurence but > SDRC is waiting for read completion.SDRC is not sensitive to > the warm reset, but the interconect is reset on the fly, > thus causing a misalignment between SDRC logic, interconect > logic and DDR memory state. > > Root cause description: A corrupted read transaction is > issued to a closed row: (address0, bank0) instead of the > expected read access, violating protocol. > > Failure signature: Once the failure occurs and system has > restarted, memory content is not accessible.SDRC registers > can be accessed successfully, until 1st access to memory > location is performed. After 1st access to memory is done, > SDRC is stuck. > > WORKAROUND > Steps to perform before a SW reset is trigged, if user needs > to generate a SW reset and keep DDR memory content: > 1. Enable self-refresh on idle request > 2. Put SDRC in idle > 3. Wait until SDRC goes to idle > 4. Generate SW reset > > Steps to perform after warm reset occurs: > If HW warm reset is the source, apply below steps before > any accesses to SDRAM: > 1. Reset SMS and SDRC > 2. Re-initialize SMS, SDRC and memory > > This would need the u-boot/x-loader workaround changes > as well for the reboot to work correctly. > > Thanks to Paul Walmsley <paul@xxxxxxxxx> for suggesting > usefull changes. > > Signed-off-by: Teerth Reddy <teerth@xxxxxx> This patch doesn't work on the BeagleBoard Rev C2 here. After running 'init 6' to reboot the system, the kernel hangs after: Rebooting... Restarting system. Could you please doublecheck this patch? This patch also adds a sparse warning - please fix that too, - Paul -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
