thermal: exynos: Reduce severity of too early temperature read

Thermal core tries to read temperature during sensor registering in
thermal_zone_of_sensor_register().  In that time Exynos TMU driver and
hardware are not yet initialized.  Commit 0eb875d88aaa ("thermal:
exynos: Reading temperature makes sense only when TMU is turned on")
added a boolean flag to prevent reading bogus temperature in such
case but it exposed warning message during boot:
	[    3.864913] thermal thermal_zone0: failed to read out thermal zone (-22)

Return EAGAIN in such case to skip omitting such message because it
might mislead user.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
index 3b20309789e3..c24969d740d1 100644
--- a/drivers/thermal/samsung/exynos_tmu.c
+++ b/drivers/thermal/samsung/exynos_tmu.c
@@ -666,8 +666,14 @@ static int exynos_get_temp(void *p, int *temp)
         struct exynos_tmu_data *data = p;
         int value, ret = 0;
 
-        if (!data || !data->tmu_read || !data->enabled)
+        if (!data || !data->tmu_read)
                 return -EINVAL;
+        else if (!data->enabled)
+                /*
+                 * Called too early, probably
+                 * from thermal_zone_of_sensor_register().
+                 */
+                return -EAGAIN;
 
         mutex_lock(&data->lock);
         clk_enable(data->clk);