gpu: nvgpu: support negative temperatures

Jira DNVGPU-166

Change-Id: Id0561d49c64096ad5cbcd23bd371b49b2e0db57c
Signed-off-by: Thomas Fleury <tfleury@nvidia.com>
Reviewed-on: http://git-master/r/1245557
(cherry picked from commit 2e0269c76fdda5c8e1a30ca7ef73a08ebe644f88)
Reviewed-on: http://git-master/r/1267156
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

2 files changed, 5 insertions, 4 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/ctrl_gk20a.c b/drivers/gpu/nvgpu/gk20a/ctrl_gk20a.c
index 23fbdce0..6768dbeb 100644
--- a/drivers/gpu/nvgpu/gk20a/ctrl_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/ctrl_gk20a.c
@@ -1278,9 +1278,7 @@ static int nvgpu_gpu_get_temperature(struct gk20a *g,
 
         gk20a_idle(g->dev);
 
-        /* Convert from standard S24.8 fixed point to mC */
-        if (!err)
-                args->temperature = (temp_f24_8 * 1000) / 256;
+        args->temp_f24_8 = (s32)temp_f24_8;
 
         return err;
 }
diff --git a/include/uapi/linux/nvgpu.h b/include/uapi/linux/nvgpu.h
index 16aa51b2..0aeea4f0 100644
--- a/include/uapi/linux/nvgpu.h
+++ b/include/uapi/linux/nvgpu.h
@@ -743,7 +743,10 @@ struct nvgpu_gpu_get_power_args {
 
 struct nvgpu_gpu_get_temperature_args {
         __u32 reserved[3];
-        __u32 temperature;      /* mC */
+        /* Temperature in signed fixed point format SFXP24.8
+         *    Celsius = temp_f24_8 / 256.
+         */
+        __s32 temp_f24_8;
 };
 
 #define NVGPU_GPU_IOCTL_ZCULL_GET_CTX_SIZE \