[U-Boot] [PATCH] debug_uart: output CR along with LF

[Tim Chick]

Please see below:

> 
> 
> Hi Tim,
> 
> 2016-04-05 0:16 GMT+09:00 Tim Chick <Tim.Chick at mediatek.com>:
>> Hi Masahiro,
>>
>> This patch breaks the debug_uart on my MIPS board. It means printascii now uses the stack, and my board does not have a stack when debug_uart_init is called. debug_uart_init calls printascii if DEBUG_UART_ANNOUNCE is defined.
>>
>> The patch below fixes it, and keeps your change:
>>
> 
> I think the current implementation of debug_uart
> requires the stack, anyway.
> 
No, I'm quite sure it does not, on MIPS at least. I do not have a stack.
My platform has no SRAM, so I don't have a stack until I can get the
DRAM working.

> I am not sure your patch is the right approach
> because your solution seems dependent on your compiler behavior.
>
I believe it just relies on inline, which is used elsewhere to enable
debug_uart to work without a stack.

> I tried your patch with CONFIG_DEBUG_UART_ANNOUNCE=y,
> but my ARM compiler still produced debug_uart_init
> code with the stack.
> 

It shouldn't do, it should honor the inline keyword I think. I'm using
gcc on mips, and get (with my code):

9c023598 <printascii>:
9c023598:       2406000a        li      a2,10
9c02359c:       3c02b000        lui     v0,0xb000
9c0235a0:       1000000e        b       9c0235dc <printascii+0x44>
9c0235a4:       2405000d        li      a1,13
9c0235a8:       14660006        bne     v1,a2,9c0235c4 <printascii+0x2c>
9c0235ac:       24840001        addiu   a0,a0,1
9c0235b0:       90480c14        lbu     t0,3092(v0)

static inline void _debug_uart_putc(int ch)
{
        struct NS16550 *com_port = (struct NS16550 *)CONFIG_DEBUG_UART_BASE;

        while (!(serial_din(&com_port->lsr) & UART_LSR_THRE))
9c0235b4:       31080020        andi    t0,t0,0x20
9c0235b8:       1100fffd        beqz    t0,9c0235b0 <printascii+0x18>
9c0235bc:       00000000        nop
9c0235c0:       a0450c00        sb      a1,3072(v0)
9c0235c4:       90480c14        lbu     t0,3092(v0)

...


You can see it inlines the code. With your change, it pushed data to the
stack and called printascii as a subroutine.

Thanks,
Tim