On Fri, Oct 21, 2022 at 11:34:24AM -0400, Joe Korty wrote:

arm64: XGene-1 has a 31 bit, not a 32 bit, arch timer.

Fixes: 012f188504528b8cb32f441ac3bd9ea2eba39c9e ("clocksource/drivers/arm_arch_timer: Work around broken CVAL implementations")

Testing: On an 8-cpu Mustang, the following sequence no longer locks up the system:

 echo 0 >/proc/sys/kernel/watchdog
 for i in {0..7}; do taskset -c $i echo hi there $i; done

Stable: To be applied to 5.16 and above, once accepted by mainline.

Signed-off-by: Joe Korty joe.korty@concurrent-rt.com

Index: b/drivers/clocksource/arm_arch_timer.c

--- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -805,7 +805,7 @@ static u64 __arch_timer_check_delta(void const struct midr_range broken_cval_midrs[] = { /* * XGene-1 implements CVAL in terms of TVAL, meaning

•  * that the maximum timer range is 32bit. Shame on them.
  

•  * that the maximum timer range is 31bit. Shame on them.
  

  */ MIDR_ALL_VERSIONS(MIDR_CPU_MODEL(ARM_CPU_IMP_APM, APM_CPU_PART_POTENZA)),

@@ -813,8 +813,8 @@ static u64 __arch_timer_check_delta(void }; if (is_midr_in_range_list(read_cpuid_id(), broken_cval_midrs)) {

• pr_warn_once("Broken CNTx_CVAL_EL1, limiting width to 32bits");
  

• return CLOCKSOURCE_MASK(32);
  

• pr_warn_once("Broken CNTx_CVAL_EL1, limiting width to 31bits");
  

• return CLOCKSOURCE_MASK(31);
  

  }

#endif return CLOCKSOURCE_MASK(arch_counter_get_width());

<formletter>

This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.

</formletter>