Re: [RFC. PATCH] earlycon: Remove hardcoded port->uartclk initialization in of_setup_earlycon

From: Matt Redfearn
Date: Mon Apr 23 2018 - 09:16:47 EST

On 23/04/18 10:27, Michal Simek wrote:
There is no reason to initialize uartclk to BASE_BAUD * 16 for DT based

Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>

It looks like from history that portclk = BASE_BAUD * 16 was setup to
get on calculation on x86 (divisor = 1) but it shouldn't be needed on DT based
system. That's why I think that there is no DT based system which really
requires this line.

Hi Michal,

This is fine for the MIPS generic platform (tested on Boston board) which was broken by some earlycon changes a few versions ago. Also tested on a MIPS pistachio board. As long as the bootloader has configured the uart divisor, earlycon should work as long as my patch "serial: 8250_early: Only set divisor if valid clk & baud" is applied to avoid a bad divisor getting calculated.

Tested-by: Matt Redfearn <matt.redfearn@xxxxxxxx>


drivers/tty/serial/earlycon.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index a24278380fec..c12b1edcdd8e 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -244,7 +244,6 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
return -ENXIO;
port->mapbase = addr;
- port->uartclk = BASE_BAUD * 16;
val = of_get_flat_dt_prop(node, "reg-offset", NULL);
if (val)