This is a note to let you know that I've just added the patch titled
clk: qcom: reset: Allow specifying custom reset delay
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-allow-specifying-custom-reset-delay.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 067e05754a2fc63992a2ffd40b2208374451a2b2
Author: Stephan Gerhold <stephan.gerhold@xxxxxxxxxxxxxxx>
Date: Wed Jul 6 15:41:29 2022 +0200
clk: qcom: reset: Allow specifying custom reset delay
[ Upstream commit 2cb8a39b6781ea23accd1fa93b3ad000d0948aec ]
The amount of time required between asserting and deasserting the reset
signal can vary depending on the involved hardware component. Sometimes
1 us might not be enough and a larger delay is necessary to conform to
the specifications.
Usually this is worked around in the consuming drivers, by replacing
reset_control_reset() with a sequence of reset_control_assert(), waiting
for a custom delay, followed by reset_control_deassert().
However, in some cases the driver making use of the reset is generic and
can be used with different reset controllers. In this case the reset
time requirement is better handled directly by the reset controller
driver.
Make this possible by adding an "udelay" field to the qcom_reset_map
that allows setting a different reset delay (in microseconds).
Signed-off-by: Stephan Gerhold <stephan.gerhold@xxxxxxxxxxxxxxx>
Signed-off-by: Bjorn Andersson <andersson@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220706134132.3623415-4-stephan.gerhold@xxxxxxxxxxxxxxx
Stable-dep-of: 2f8cf2c3f3e3 ("clk: qcom: reset: Ensure write completion on reset de/assertion")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/clk/qcom/reset.c b/drivers/clk/qcom/reset.c
index 0324d8daab9bc..fc68c8fa30ac7 100644
--- a/drivers/clk/qcom/reset.c
+++ b/drivers/clk/qcom/reset.c
@@ -21,8 +21,10 @@
static int qcom_reset(struct reset_controller_dev *rcdev, unsigned long id)
{
+ struct qcom_reset_controller *rst = to_qcom_reset_controller(rcdev);
+
rcdev->ops->assert(rcdev, id);
- udelay(1);
+ udelay(rst->reset_map[id].udelay ?: 1); /* use 1 us as default */
rcdev->ops->deassert(rcdev, id);
return 0;
}
diff --git a/drivers/clk/qcom/reset.h b/drivers/clk/qcom/reset.h
index cda877927d43a..3e30f6724c7a4 100644
--- a/drivers/clk/qcom/reset.h
+++ b/drivers/clk/qcom/reset.h
@@ -19,6 +19,7 @@
struct qcom_reset_map {
unsigned int reg;
u8 bit;
+ u8 udelay;
};
struct regmap;
