From 68435ffc1c1a306111073c71f599b272be04f509 Mon Sep 17 00:00:00 2001 From: Konrad Dybcio Date: Tue, 6 Feb 2024 19:43:36 +0100 Subject: [PATCH] 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 Link: https://lore.kernel.org/r/20240105-topic-venus_reset-v2-3-c37eba13b5ce@linaro.org Signed-off-by: Bjorn Andersson Signed-off-by: Sasha Levin --- drivers/clk/qcom/reset.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/clk/qcom/reset.c b/drivers/clk/qcom/reset.c index 338b1210c8f8..5a44dc8bd25f 100644 --- a/drivers/clk/qcom/reset.c +++ b/drivers/clk/qcom/reset.c @@ -32,7 +32,12 @@ 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)