From: John Crispin Date: Tue, 1 Aug 2017 04:53:38 +0000 (+0200) Subject: ralink: fix rcu_sched stalls on mt7621 X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=6f4a903533361a2906a4d94ac6f597cd9c6c47bc;p=librecmc%2Flibrecmc.git ralink: fix rcu_sched stalls on mt7621 there were 2 bugs *) core1 came up with a bad bogo mips, looks like the clock needed time to stabilize *) HPT frequency was not set making r4k timers not come up properly Backport of 9551d91b1d6 "ralink: fix rcu_sched stalls on mt7621". Signed-off-by: John Crispin --- diff --git a/target/linux/ramips/patches-4.4/101-mt7621-timer.patch b/target/linux/ramips/patches-4.4/101-mt7621-timer.patch new file mode 100644 index 0000000000..02497bc1d2 --- /dev/null +++ b/target/linux/ramips/patches-4.4/101-mt7621-timer.patch @@ -0,0 +1,98 @@ +--- a/arch/mips/ralink/mt7621.c ++++ b/arch/mips/ralink/mt7621.c +@@ -18,6 +18,7 @@ + #include + #include + #include ++#include + + #include + +@@ -179,6 +180,58 @@ bool plat_cpu_core_present(int core) + return true; + } + ++#define LPS_PREC 8 ++/* ++* Re-calibration lpj(loop-per-jiffy). ++* (derived from kernel/calibrate.c) ++*/ ++static int udelay_recal(void) ++{ ++ unsigned int i, lpj = 0; ++ unsigned long ticks, loopbit; ++ int lps_precision = LPS_PREC; ++ ++ lpj = (1<<12); ++ ++ while ((lpj <<= 1) != 0) { ++ /* wait for "start of" clock tick */ ++ ticks = jiffies; ++ while (ticks == jiffies) ++ /* nothing */; ++ ++ /* Go .. */ ++ ticks = jiffies; ++ __delay(lpj); ++ ticks = jiffies - ticks; ++ if (ticks) ++ break; ++ } ++ ++ /* ++ * Do a binary approximation to get lpj set to ++ * equal one clock (up to lps_precision bits) ++ */ ++ lpj >>= 1; ++ loopbit = lpj; ++ while (lps_precision-- && (loopbit >>= 1)) { ++ lpj |= loopbit; ++ ticks = jiffies; ++ while (ticks == jiffies) ++ /* nothing */; ++ ticks = jiffies; ++ __delay(lpj); ++ if (jiffies != ticks) /* longer than 1 tick */ ++ lpj &= ~loopbit; ++ } ++ printk(KERN_INFO "%d CPUs re-calibrate udelay(lpj = %d)\n", NR_CPUS, lpj); ++ ++ for(i=0; i< NR_CPUS; i++) ++ cpu_data[i].udelay_val = lpj; ++ ++ return 0; ++} ++device_initcall(udelay_recal); ++ + void prom_soc_init(struct ralink_soc_info *soc_info) + { + void __iomem *sysc = (void __iomem *) KSEG1ADDR(MT7621_SYSC_BASE); +--- a/arch/mips/ralink/Kconfig ++++ b/arch/mips/ralink/Kconfig +@@ -56,6 +56,7 @@ choice + select COMMON_CLK + select CLKSRC_MIPS_GIC + select HW_HAS_PCI ++ select GENERIC_CLOCKEVENTS_BROADCAST + endchoice + + choice +--- a/arch/mips/ralink/timer-gic.c ++++ b/arch/mips/ralink/timer-gic.c +@@ -12,6 +12,7 @@ + #include + #include + #include ++#include + + #include "common.h" + +@@ -19,6 +20,8 @@ void __init plat_time_init(void) + { + ralink_of_remap(); + ++ mips_hpt_frequency = 880000000 / 2; ++ + of_clk_init(NULL); + clocksource_probe(); + }