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authorCaesar Wang <wxt@rock-chips.com>2015-01-25 05:11:11 +0300
committerEduardo Valentin <edubezval@gmail.com>2015-01-25 06:38:36 +0300
commit1e9a1aea7a05a1c8a7ece72b02d8077089f9e4d5 (patch)
tree719fd65616eefd8a963e5e3b5bce888b1506f773 /drivers/thermal
parent1fd2273f966a095ff825cb20304878fdf14a6b45 (diff)
downloadlinux-1e9a1aea7a05a1c8a7ece72b02d8077089f9e4d5.tar.xz
thermal: rockchip: make temperature reporting much more accurate
In general, the kernel should report temperature readings exactly as reported by the hardware. The cpu / gpu thermal driver works in 5 degree increments,but we ought to do more accurate. The temperature will do linear interpolation between the entries in the table. Test= $md5sum /dev/zero & $while true; do grep "" /sys/class/thermal/thermal_zone[1-2]/temp; sleep .5; done e.g. We can get the result as follows: /sys/class/thermal/thermal_zone1/temp:39994 /sys/class/thermal/thermal_zone2/temp:39086 /sys/class/thermal/thermal_zone1/temp:39994 /sys/class/thermal/thermal_zone2/temp:39540 /sys/class/thermal/thermal_zone1/temp:39540 /sys/class/thermal/thermal_zone2/temp:39540 /sys/class/thermal/thermal_zone1/temp:39540 /sys/class/thermal/thermal_zone2/temp:39994 Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Daniel Kurtz <djkurtz@chromium.org> Signed-off-by: Caesar Wang <wxt@rock-chips.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
Diffstat (limited to 'drivers/thermal')
-rw-r--r--drivers/thermal/rockchip_thermal.c36
1 files changed, 23 insertions, 13 deletions
diff --git a/drivers/thermal/rockchip_thermal.c b/drivers/thermal/rockchip_thermal.c
index 9c6ce548e363..3aa46ac7cdbc 100644
--- a/drivers/thermal/rockchip_thermal.c
+++ b/drivers/thermal/rockchip_thermal.c
@@ -193,19 +193,20 @@ static u32 rk_tsadcv2_temp_to_code(long temp)
static long rk_tsadcv2_code_to_temp(u32 code)
{
- int high, low, mid;
-
- low = 0;
- high = ARRAY_SIZE(v2_code_table) - 1;
- mid = (high + low) / 2;
-
- if (code > v2_code_table[low].code || code < v2_code_table[high].code)
- return 125000; /* No code available, return max temperature */
+ unsigned int low = 0;
+ unsigned int high = ARRAY_SIZE(v2_code_table) - 1;
+ unsigned int mid = (low + high) / 2;
+ unsigned int num;
+ unsigned long denom;
+
+ /* Invalid code, return -EAGAIN */
+ if (code > TSADCV2_DATA_MASK)
+ return -EAGAIN;
- while (low <= high) {
- if (code >= v2_code_table[mid].code && code <
- v2_code_table[mid - 1].code)
- return v2_code_table[mid].temp;
+ while (low <= high && mid) {
+ if (code >= v2_code_table[mid].code &&
+ code < v2_code_table[mid - 1].code)
+ break;
else if (code < v2_code_table[mid].code)
low = mid + 1;
else
@@ -213,7 +214,16 @@ static long rk_tsadcv2_code_to_temp(u32 code)
mid = (low + high) / 2;
}
- return 125000;
+ /*
+ * The 5C granularity provided by the table is too much. Let's
+ * assume that the relationship between sensor readings and
+ * temperature between 2 table entries is linear and interpolate
+ * to produce less granular result.
+ */
+ num = v2_code_table[mid].temp - v2_code_table[mid - 1].temp;
+ num *= v2_code_table[mid - 1].code - code;
+ denom = v2_code_table[mid - 1].code - v2_code_table[mid].code;
+ return v2_code_table[mid - 1].temp + (num / denom);
}
/**