Extend R4000/R4400 CPU erratum workaround to all revisions

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Merge tag 'mips-fixes_5.18_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux

Pull MIPS fix from Thomas Bogendoerfer:
 "Extend R4000/R4400 CPU erratum workaround to all revisions"

* tag 'mips-fixes_5.18_1' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MIPS: Fix CP0 counter erratum detection for R4k CPUs

arch/mips/include/asm/timex.h

@@ -40,9 +40,9 @@
 typedef unsigned int cycles_t;
 
 /*
- * On R4000/R4400 before version 5.0 an erratum exists such that if the
- * cycle counter is read in the exact moment that it is matching the
- * compare register, no interrupt will be generated.
+ * On R4000/R4400 an erratum exists such that if the cycle counter is
+ * read in the exact moment that it is matching the compare register,
+ * no interrupt will be generated.
  *
  * There is a suggested workaround and also the erratum can't strike if
  * the compare interrupt isn't being used as the clock source device.
@@ -63,7 +63,7 @@ static inline int can_use_mips_counter(unsigned int prid)
 	if (!__builtin_constant_p(cpu_has_counter))
 		asm volatile("" : "=m" (cpu_data[0].options));
 	if (likely(cpu_has_counter &&
-		   prid >= (PRID_IMP_R4000 | PRID_REV_ENCODE_44(5, 0))))
+		   prid > (PRID_IMP_R4000 | PRID_REV_ENCODE_44(15, 15))))
 		return 1;
 	else
 		return 0;

arch/mips/kernel/time.c

@@ -141,15 +141,10 @@ static __init int cpu_has_mfc0_count_bug(void)
 	case CPU_R4400MC:
 		/*
 		 * The published errata for the R4400 up to 3.0 say the CPU
-		 * has the mfc0 from count bug.
+		 * has the mfc0 from count bug.  This seems the last version
+		 * produced.
 		 */
-		if ((current_cpu_data.processor_id & 0xff) <= 0x30)
-			return 1;
-
-		/*
-		 * we assume newer revisions are ok
-		 */
-		return 0;
+		return 1;
 	}
 
 	return 0;