On 8/15/20 3:53 AM, Heinrich Schuchardt wrote:
On 8/5/20 2:19 PM, Heinrich Schuchardt wrote:
On 05.08.20 13:45, Sean Anderson wrote:
On 8/3/20 2:20 PM, Heinrich Schuchardt wrote:
On 03.08.20 16:08, Sean Anderson wrote:
Maybe. Because we are configuring the PLL, the CPU clock is temporarily set to the in0 oscillator, so the timer would give an incorrect delay. However, it would probably be fine even if incorrect. The original reason I used nops is because that is what the SDK does in its PLL configuration function [1]. I believe I tried using udelay at one point, but I don't remember whether I had any issues with it.
--Sean
[1] https://github.com/kendryte/kendryte-standalone-sdk/blob/develop/lib/drivers...
This is what udelay(1) gets compiled to:
000000000000004a <.LBE106>: udelay(1); 4a: 4505 li a0,1
000000000000004c <.LVL21>: 4c: 00000097 auipc ra,0x0 50: 000080e7 jalr ra # 4c <.LVL21>
Somehow udelay() seems not to be fully implemented and the platform. So I think we should stay with the nop() macro.
Hm, I don't see this generated code. What function is that a disassembly of?
I was disassembling
riscv64-linux-gnu-objdump -D -S drivers/clk/kendryte/pll.o
If I disassemble the file u-boot function k210_pll_enable seems to be ok. nop()s replaced by udelay(1):
writel(reg, pll->reg); 80012524: 7518 ld a4,40(a0) __iowmb(); 80012526: 0550000f fence ow,ow reg |= K210_PLL_RESET; 8001252a: 003006b7 lui a3,0x300 8001252e: 8fd5 or a5,a5,a3 __arch_putl(val, addr); 80012530: c31c sw a5,0(a4) udelay(1); 80012532: 4505 li a0,1 80012534: 612200ef jal ra,80032b46 <udelay> writel(reg, pll->reg); 80012538: 741c ld a5,40(s0) __iowmb(); 8001253a: 0550000f fence ow,ow
So it was simply the link step missing to show the call.
But anyway which way do you want the patch?
I think the patch as-is is fine.
--Sean
Hello Sean,
did I miss you reply?> Best regards
Heinrich
Best regards
Heinrich
$ riscv64-linux-gnu-objdump -S --disassemble=__udelay u-boot
u-boot: file format elf64-littleriscv
Disassembly of section .text:
Disassembly of section .text_rest:
00000000800197f8 <__udelay>: do_div(tick, 1000000); return tick; }
void __weak __udelay(unsigned long usec) { 800197f8: 1101 addi sp,sp,-32 800197fa: ec06 sd ra,24(sp) 800197fc: e822 sd s0,16(sp) 800197fe: e426 sd s1,8(sp) 80019800: 84aa mv s1,a0 uint64_t tmp;
tmp = get_ticks() + usec_to_tick(usec); /* get current timestamp */ 80019802: f7bff0ef jal ra,8001977c <get_ticks> 80019806: 842a mv s0,a0 80019808: 8526 mv a0,s1 8001980a: fcbff0ef jal ra,800197d4 <usec_to_tick> 8001980e: 942a add s0,s0,a0
while (get_ticks() < tmp+1) /* loop till event */ 80019810: 0405 addi s0,s0,1 80019812: f6bff0ef jal ra,8001977c <get_ticks> 80019816: fe856ee3 bltu a0,s0,80019812 <__udelay+0x1a> /*NOP*/; } 8001981a: 60e2 ld ra,24(sp) 8001981c: 6442 ld s0,16(sp) 8001981e: 64a2 ld s1,8(sp) 80019820: 6105 addi sp,sp,32 80019822: 8082 ret
--Sean