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Subject[PATCH 2/2 v3] MIPS: Ingenic: Disable abandoned HPTLB function.
Date
JZ4760/JZ4770/JZ4775/X1000/X1500 has an abandoned huge page tlb,
this mode is not compatible with the MIPS standard, it will cause
tlbmiss and into an infinite loop (line 21 in the tlb-funcs.S)
when starting the init process. write 0xa9000000 to cp0 register 5
sel 4 to disable this function to prevent getting stuck. Confirmed
by Ingenic, this operation will not adversely affect processors
without HPTLB function.

Signed-off-by: Zhou Yanjie <zhouyanjie@zoho.com>
---
arch/mips/include/asm/mipsregs.h | 6 ++++++
arch/mips/kernel/cpu-probe.c | 21 +++++++++++++++++++--
2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index bdbdc19..0d5a309 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -689,6 +689,9 @@
#define MIPS_CONF7_IAR (_ULCAST_(1) << 10)
#define MIPS_CONF7_AR (_ULCAST_(1) << 16)

+/* Ingenic HPTLB off bits */
+#define XBURST_PAGECTRL_HPTLB_DIS 0xa9000000
+
/* Ingenic Config7 bits */
#define MIPS_CONF7_BTB_LOOP_EN (_ULCAST_(1) << 4)

@@ -1971,6 +1974,9 @@ do { \
#define read_c0_brcm_sleepcount() __read_32bit_c0_register($22, 7)
#define write_c0_brcm_sleepcount(val) __write_32bit_c0_register($22, 7, val)

+/* Ingenic page ctrl register */
+#define write_c0_page_ctrl(val) __write_32bit_c0_register($5, 4, val)
+
/*
* Macros to access the guest system control coprocessor
*/
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 7a0e33c..3b5f4fb 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -1965,13 +1965,30 @@ static inline void cpu_probe_ingenic(struct cpuinfo_mips *c, unsigned int cpu)
break;
}

+ switch (c->processor_id & PRID_COMP_MASK) {
+ /*
+ * The config0 register in the XBurst CPUs with a processor ID of
+ * PRID_COMP_INGENIC_D1 has an abandoned huge page tlb mode, this
+ * mode is not compatible with the MIPS standard, it will cause
+ * tlbmiss and into an infinite loop (line 21 in the tlb-funcs.S)
+ * when starting the init process. After chip reset, the default
+ * is HPTLB mode, Write 0xa9000000 to cp0 register 5 sel 4 to
+ * switch back to VTLB mode to prevent getting stuck.
+ */
+ case PRID_COMP_INGENIC_D1:
+ write_c0_page_ctrl(XBURST_PAGECTRL_HPTLB_DIS);
+ break;
/*
- * The config0 register in the Xburst CPUs with a processor ID of
+ * The config0 register in the XBurst CPUs with a processor ID of
* PRID_COMP_INGENIC_D0 report themselves as MIPS32r2 compatible,
* but they don't actually support this ISA.
*/
- if ((c->processor_id & PRID_COMP_MASK) == PRID_COMP_INGENIC_D0)
+ case PRID_COMP_INGENIC_D0:
c->isa_level &= ~MIPS_CPU_ISA_M32R2;
+ break;
+ default:
+ break;
+ }
}

static inline void cpu_probe_netlogic(struct cpuinfo_mips *c, int cpu)
--
2.7.4

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