@@ -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);
}
/**
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 Signed-off-by: Caesar Wang <wxt@rock-chips.com> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by: Daniel Kurtz <djkurtz@chromium.org> --- Changes in v6: It's not really need,so delete the follows: else if (code == TSADCV2_DATA_MASK) Changes in v5: Fixed some style. Changes in v4: "return -EAGAIN" instead of "return rk_tsadcv2_code_to_temp(code)" Changes in v3: Suggested-by Daniel Kurtz, the check doesn't reject "code == 0xfff" Fixed in rk_tsadcv2_code_to_temp(u32 code) Changes in v2: Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> drivers/thermal/rockchip_thermal.c | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-)