#19444: 1-wire functions are broken by broken __udelay() at ramips
-------------------------------------------------+-------------------------
Reporter: SergeiP | Owner: developers
Type: defect | Status: new
Priority: high | Milestone: Chaos
Component: kernel | Calmer (trunk)
Keywords: w1, 1-wire, udelay, calibrating | Version: Trunk
delay loop |
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I found that 1-wire doesn't work at kernel 3.18 .
Reason is broken __udelay() function.
It is broken for error in "Calibrating delay loop".
System think that processor is dowble faster:
3.18.10
[ 0.000000] genirq: Flags mismatch irq 7. 00014600 (timer) vs. 00014600
(systick)
[ 0.010000] Calibrating delay loop... 479.23 BogoMIPS (lpj=2396160)
3.10.49
[ 0.000000] Calibrating delay loop... 239.61 BogoMIPS (lpj=1198080)
[ 0.070000] pid_max: default: 32768 minimum: 301
If I patch __udelay to divide delay constant by two,
1-wire works again:
void __udelay(unsigned long us)
{
unsigned int lpj = -raw_current_cpu_data.udelay_val;
+ raw_current_cpu_data.udelay_val/2; // speed error fix
Surely, it is nor problem fix, it is problem demonstration.
"Calibrating delay loop" shoud be fixed...
--
Ticket URL: <https://dev.openwrt.org/ticket/19444>
OpenWrt <http://openwrt.org>
Opensource Wireless Router Technology
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