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From 4d4e68e0eed7ccf899bc1b3799a93ed8eb44270d Mon Sep 17 00:00:00 2001
From: Zhikui Ren <zhikui.ren@intel.com>
Date: Tue, 2 Feb 2021 14:49:28 -0800
Subject: [PATCH] DTS_CPU: filter first zero from RdPkgConfig 10
Peci command GetPkgConfig 10 can return 0 (hot) with cc 0x40
after cpu reset. Once pcode run time image is loaded
and it returns 0x8000 as DTS margin data not ready
Discard the first zero reading and return -ENODATA.
Consecutive zeros will be returned so that real hot
condition will still be detected and logged but possibly delayed
by the sensor polling period, which is normally one second.
Signed-off-by: Zhikui Ren <zhikui.ren@intel.com>
---
drivers/hwmon/peci-cputemp.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/hwmon/peci-cputemp.c b/drivers/hwmon/peci-cputemp.c
index 49670bc80530..af1c09741120 100644
--- a/drivers/hwmon/peci-cputemp.c
+++ b/drivers/hwmon/peci-cputemp.c
@@ -17,6 +17,7 @@ struct temp_group {
struct peci_sensor_data die;
u32 die_raw_prev;
struct peci_sensor_data dts;
+ u32 dts_raw_prev;
struct peci_sensor_data tcontrol;
struct peci_sensor_data tthrottle;
struct peci_sensor_data tjmax;
@@ -159,6 +160,7 @@ static int get_dts(struct peci_cputemp *priv)
s32 dts_margin;
u8 pkg_cfg[4];
int ret;
+ bool discard = false;
if (!peci_sensor_need_update(&priv->temp.dts))
return 0;
@@ -172,6 +174,24 @@ static int get_dts(struct peci_cputemp *priv)
dts_margin = le16_to_cpup((__le16 *)pkg_cfg);
+ /*
+ * There is a small window (500us) for read dts_margin (RdPkgConfig 10)
+ * to return cc 0x40, and dts_margin of 0 after cpu reset, before
+ * runtime image is loaded to set it to 0x8000 (dts reading not ready).
+ * DTS sensor is polled by user application at a slower rate than this
+ * window. Treat the first zero reading as data not available.
+ * Consecutive zeros will be returned so true hot condition is not be
+ * missed.
+ */
+ if (dts_margin == 0 && priv->temp.dts_raw_prev != 0) {
+ dev_err(priv->dev,
+ "discard first 0 reading from RdPkgConfig 10\n");
+ discard = true;
+ }
+ priv->temp.dts_raw_prev = dts_margin;
+ if (discard)
+ return -ENODATA;
+
/**
* Processors return a value of DTS reading in 10.6 format
* (10 bits signed decimal, 6 bits fractional).
--
2.17.1
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