On 1/11/20 4:38 PM, Mauro Condarelli wrote: > Thanks Joel, > unfortunately I already have that defined, even if I forgot to copy it. > I attach my full .config for reference as I have no idea what I'm > still missing. > > On 1/11/20 9:42 PM, Sean Anderson wrote: >>> Could You share a Linkit _defconfig with early serial debug enabled? >>> I'm decidedly missing something as, even enabling >>> >>> CONFIG_DEBUG_UART=y >>> CONFIG_DEBUG_UART_BASE=0x10000e00 >>> CONFIG_DEBUG_UART_CLOCK=20 >>> CONFIG_DEBUG_UART_SHIFT=2 >>> CONFIG_DEBUG_UART_ANNOUNCE=y
So it looks like your clock is way too low. The unit for the clock is Hz. From the device tree you sent, this board is based off arch/mips/dts/mt7628a.dtsi, using uart2. The clock controller for this board is compatible with "mediatek,mt7628-clk", and the driver is located in "drivers/clk/mtmips/clk-mt7628.c". From that file, the uart2 clock gets its frequency from CLK_SRC_PERI. Under mt7628_clk_get_rate, the peripheral clock source depends on the value of PERI_CLK_FROM_XTAL_SEL, which is initialized to 0 (as documented in the data sheet). Therefore, the else clause is taken (unless configured otherwise), so you should use 40000000 for your clock. >> You need to pick a debug uart driver, e.g. CONFIG_DEBUG_UART_NS16550. > As said I have it, but I'm not sure about the other parameters. > Maybe a better choice would be CONFIG_DEBUG_UART_MTK. > Having a "known good" configuration would help a lot. > > Regards > Mauro >
