clk: qcom: gdsc: Add support to update GDSC transition delay

GDSCs have multiple transition delays which are used for the GDSC FSM
states. Older targets/designs required these values to be updated from
gdsc code to certain default values for the FSM state to work as
expected. But on the newer targets/designs the values updated from the
GDSC driver can hamper the FSM state to not work as expected.

On SC7180 we observe black screens because the gdsc is being
enabled/disabled very rapidly and the GDSC FSM state does not work as
expected. This is due to the fact that the GDSC reset value is being
updated from SW.

Thus add support to update the transition delay from the clock
controller gdscs as required.

Fixes: 45dd0e5 ("clk: qcom: Add support for GDSCs)
Signed-off-by: Taniya Das <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Bjorn Andersson <[email protected]>
Signed-off-by: Stephen Boyd <[email protected]>

Author: Taniya Das

drivers/clk/qcom/gdsc.c

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2015, 2017-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, 2017-2018, 2022, The Linux Foundation. All rights reserved.
  */
 
 #include <linux/bitops.h>
@@ -35,9 +35,14 @@
 #define CFG_GDSCR_OFFSET		0x4
 
 /* Wait 2^n CXO cycles between all states. Here, n=2 (4 cycles). */
-#define EN_REST_WAIT_VAL	(0x2 << 20)
-#define EN_FEW_WAIT_VAL		(0x8 << 16)
-#define CLK_DIS_WAIT_VAL	(0x2 << 12)
+#define EN_REST_WAIT_VAL	0x2
+#define EN_FEW_WAIT_VAL		0x8
+#define CLK_DIS_WAIT_VAL	0x2
+
+/* Transition delay shifts */
+#define EN_REST_WAIT_SHIFT	20
+#define EN_FEW_WAIT_SHIFT	16
+#define CLK_DIS_WAIT_SHIFT	12
 
 #define RETAIN_MEM		BIT(14)
 #define RETAIN_PERIPH		BIT(13)
@@ -380,7 +385,18 @@ static int gdsc_init(struct gdsc *sc)
 	 */
 	mask = HW_CONTROL_MASK | SW_OVERRIDE_MASK |
 	       EN_REST_WAIT_MASK | EN_FEW_WAIT_MASK | CLK_DIS_WAIT_MASK;
-	val = EN_REST_WAIT_VAL | EN_FEW_WAIT_VAL | CLK_DIS_WAIT_VAL;
+
+	if (!sc->en_rest_wait_val)
+		sc->en_rest_wait_val = EN_REST_WAIT_VAL;
+	if (!sc->en_few_wait_val)
+		sc->en_few_wait_val = EN_FEW_WAIT_VAL;
+	if (!sc->clk_dis_wait_val)
+		sc->clk_dis_wait_val = CLK_DIS_WAIT_VAL;
+
+	val = sc->en_rest_wait_val << EN_REST_WAIT_SHIFT |
+		sc->en_few_wait_val << EN_FEW_WAIT_SHIFT |
+		sc->clk_dis_wait_val << CLK_DIS_WAIT_SHIFT;
+
 	ret = regmap_update_bits(sc->regmap, sc->gdscr, mask, val);
 	if (ret)
 		return ret;

drivers/clk/qcom/gdsc.h

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (c) 2015, 2017-2018, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2015, 2017-2018, 2022, The Linux Foundation. All rights reserved.
  */
 
 #ifndef __QCOM_GDSC_H__
@@ -22,6 +22,9 @@ struct reset_controller_dev;
  * @cxcs: offsets of branch registers to toggle mem/periph bits in
  * @cxc_count: number of @cxcs
  * @pwrsts: Possible powerdomain power states
+ * @en_rest_wait_val: transition delay value for receiving enr ack signal
+ * @en_few_wait_val: transition delay value for receiving enf ack signal
+ * @clk_dis_wait_val: transition delay value for halting clock
  * @resets: ids of resets associated with this gdsc
  * @reset_count: number of @resets
  * @rcdev: reset controller
@@ -36,6 +39,9 @@ struct gdsc {
 	unsigned int			clamp_io_ctrl;
 	unsigned int			*cxcs;
 	unsigned int			cxc_count;
+	unsigned int			en_rest_wait_val;
+	unsigned int			en_few_wait_val;
+	unsigned int			clk_dis_wait_val;
 	const u8			pwrsts;
 /* Powerdomain allowable state bitfields */
 #define PWRSTS_OFF		BIT(0)