On Thu, Jan 30, 2020 at 05:11:55PM +0100, Nicolas Saenz Julienne wrote: > BTW did you had the oportunity to have a go at the patch? I've just performed a quick test and it doesn't work for me. If I add stdout-path = "serial1:115200n8"; to the chosen node, I only get a regular console with this patch, not an earlycon. > > The problem is that in mainline, bcm2835_defconfig contains: > > CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE=y > > > > Likewise in the Foundation's downstream tree, bcmrpi_defconfig as well > > as bcm2711_defconfig and bcm2709_defconfig contain: > > CONFIG_CPU_FREQ_DEFAULT_GOV_POWERSAVE=y > > > > In contrast to this, we set the following on Revolution Pi devices: > > CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE=y > > > > Downclocking influences not only the uart1 baud rate but also the > > spi0 clock. We attach Ethernet chips to spi0, throughput was > > significantly worse with the ondemand governor (which is what we > > used previously). We felt that maximum Ethernet performance > > outweighs the relatively small powersaving gains. > > In that regard I suggest you use the upstream cpufreq driver which > behaves properly in that regard. It disables GPU freq scaling, so as to > change CPU frequencies without SPI/I2C/UART issues. Okay, I'll take a look. But the uart1 baudrate will still be wrong if the firmware downclocks because of overheating, right? Thanks, Lukas
