On Tue, 20 Feb 2024 at 17:09, Caleb Connolly <[email protected]> wrote: > > > > On 20/02/2024 06:08, Sumit Garg wrote: > > On Fri, 16 Feb 2024 at 02:22, Caleb Connolly <[email protected]> > > wrote: > >> > >> Introduce support for early debugging. This relies on the previous stage > >> bootloader to initialise the UART clocks, when running with U-Boot as > >> the primary bootloader this feature doesn't work. It will require a way > >> to configure the clocks before the driver model is available. > >> > >> Signed-off-by: Caleb Connolly <[email protected]> > >> --- > >> drivers/serial/Kconfig | 8 ++++++++ > >> drivers/serial/serial_msm.c | 37 +++++++++++++++++++++++++++++++++++++ > >> 2 files changed, 45 insertions(+) > >> > >> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig > >> index 26460c4e0cab..fbd351a47859 100644 > >> --- a/drivers/serial/Kconfig > >> +++ b/drivers/serial/Kconfig > >> @@ -319,6 +319,14 @@ config DEBUG_UART_S5P > >> will need to provide parameters to make this work. The driver > >> will > >> be available until the real driver-model serial is running. > >> > >> +config DEBUG_UART_MSM > >> + bool "Qualcomm QUP UART debug" > >> + depends on ARCH_SNAPDRAGON > > > > Since this debug UART only works for chainloaded configuration, can we > > somehow add explicit dependency here? Something like !REMAKE_ELF? > > With a small patch (which didn't make it into v4 apparently) the > apq8016_clk_init_uart() function from clock-apq8016 can be adjusted to > just take a base address rather than "struct msm_clk_priv". It can then > be called from debug_uart_init() and allows for debug UART to be used > when U-Boot is running as the first stage. > > This is definitely not ideal (although fwiw if the GPLLs were configured > right then this same function could maybe work on QCS404 as well
QCS404 is chainloaded config too, so the debug UART should work there. > - the > RCGs are at the same physical addresses), but I don't think gating it > behind REMAKE_ELF or something is a great solution here. I don't have a strong opinion here and I could live with just a documentation update for debug UART too. -Sumit
