Hi Marek, Am Monday 16 November 2015, 12:01:36 schrieben Sie: > On Sunday, November 15, 2015 at 10:47:12 PM, Michael Heimpold wrote: > > At the moment, the desired brownout is at 1.0V. However, > > this setting cannot be realized by hardware since we have > > only 3 bits to represent the voltage difference from the > > target value. > > > > Target value is 1500 mV, brownout target is 1000 mV, > > voltage steps are 25 mV. > > > > Register content calculation: > > (1500 [mV] - 1000 [mV]) / 25 [mV] = 20 (decimal) = 0x14 > > > > Register takes only 3 bits, that is 0x4. > > > > But 0x4 * 25 [mV] = 100 [mV], that means that actual > > brownout level is 1500 [mV] - 100 [mV] = 1.4 V. > > > > Minimum possible BO level is > > > > 1500 [mV] - 0x7 * 25 [mV] = 1315 [mV]. > > > > So lets use this value as desired BO value (which is > > also the same as FSL bootlets use). > > > > Signed-off-by: Michael Heimpold <m...@heimpold.de> > > Cc: Marek Vasut <ma...@denx.de> > > Cc: Otavio Salvador <ota...@ossystems.com.br> > > Cc: Fabio Estevam <fabio.este...@freescale.com> > > Uh, nice find. How did you find it?
I was investigating a boot stall with I2SE's Duckbill devices and since we're about to switch from FSL bootlets to U-Boot, I compared the register settings. Then I stumbled about the comment and wondered whether 1.0V BO level makes sense for 1.5V target voltage... Best regards, Michael Heimpold > > Acked-by: Marek Vasut <ma...@denx.de> > > Best regards, > Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
