clk: qcom: reset: Ensure write completion on reset de/assertion

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 <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bjorn Andersson <[e-mail]>

drivers/clk/qcom/reset.c

···
 	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)