This is a note to let you know that I've just added the patch titled
clk: qcom: reset: Ensure write completion on reset de/assertion
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
clk-qcom-reset-ensure-write-completion-on-reset-de-a.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6bcb599b1f788d39440f4cad83aa79c84d649ab4
Author: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
Date: Tue Feb 6 19:43:36 2024 +0100
clk: qcom: reset: Ensure write completion on reset de/assertion
[ Upstream commit 2f8cf2c3f3e3f7ef61bd19abb4b0bb797ad50aaf ]
Trying to toggle the resets in a rapid fashion can lead to the changes
not actually arriving at the clock controller block when we expect them
to. This was observed at least on SM8250.
Read back the value after regmap_update_bits to ensure write completion.
Fixes: b36ba30c8ac6 ("clk: qcom: Add reset controller support")
Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240105-topic-venus_reset-v2-3-c37eba13b5ce@xxxxxxxxxx
Signed-off-by: Bjorn Andersson <andersson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/clk/qcom/reset.c b/drivers/clk/qcom/reset.c
index 252d7abf577e3..3a1cfc2dd94c9 100644
--- a/drivers/clk/qcom/reset.c
+++ b/drivers/clk/qcom/reset.c
@@ -40,7 +40,12 @@ static int qcom_reset_set_assert(struct reset_controller_dev *rcdev,
map = &rst->reset_map[id];
mask = map->bitmask ? map->bitmask : BIT(map->bit);
- return regmap_update_bits(rst->regmap, map->reg, mask, assert ? mask : 0);
+ regmap_update_bits(rst->regmap, map->reg, mask, assert ? mask : 0);
+
+ /* Read back the register to ensure write completion, ignore the value */
+ regmap_read(rst->regmap, map->reg, &mask);
+
+ return 0;
}
static int qcom_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
