On 4/3/2023 13:00, Box, David E wrote:
On Fri, 2023-03-31 at 20:05 +0200, Rafael J. Wysocki wrote:
On Thu, Mar 30, 2023 at 9:45 PM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
intel_pmc_core displays a warning when the module parameter
`warn_on_s0ix_failures` is set and a suspend didn't get to a HW sleep
state.
Report this to the standard kernel reporting infrastructure so that
userspace software can query after the suspend cycle is done.
Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
---
v4->v5:
* Reword commit message
---
drivers/platform/x86/intel/pmc/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/platform/x86/intel/pmc/core.c
b/drivers/platform/x86/intel/pmc/core.c
index e2f171fac094..980af32dd48a 100644
--- a/drivers/platform/x86/intel/pmc/core.c
+++ b/drivers/platform/x86/intel/pmc/core.c
@@ -1203,6 +1203,8 @@ static inline bool pmc_core_is_s0ix_failed(struct
pmc_dev *pmcdev)
if (pmc_core_dev_state_get(pmcdev, &s0ix_counter))
return false;
+ pm_set_hw_sleep_time(s0ix_counter - pmcdev->s0ix_counter);
+
Maybe check if this is really accumulating? In case of a counter
overflow, for instance?
Overflow is likely on some systems. The counter is only 32-bit and at our
smallest granularity of 30.5us per tick it could overflow after a day and a half
of s0ix time, though most of our systems have a higher granularity that puts
them around 6 days.
This brings up an issue that the attribute cannot be trusted if the system is
suspended for longer than the maximum hardware counter time. Should be noted in
the Documentation.
I think it would be rather confusing for userspace having to account for
this and it's better to abstract it in the kernel.
How can you discover the granularity a system can support?
How would you know overflow actually happened? Is there a bit somewhere
else that could tell you?
In terms of ABI how about when we know overflow occurred and userspace
reads the sysfs file we return -EOVERFLOW instead of a potentially bad
value?
