[PATCH 36/53] drm/i915/dg2: Don't wait for AUX power well enable ACKs

[Matt Roper]

On DG2 we're supposed to just wait 600us after programming the well
before moving on; there won't be an ack from the hardware.

Bspec: 49296
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 .../gpu/drm/i915/display/intel_display_power.c   | 16 ++++++++++++++++
 .../gpu/drm/i915/display/intel_display_power.h   |  6 ++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_power.c b/drivers/gpu/drm/i915/display/intel_display_power.c
index 285380079aab..c34ff0947b85 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.c
+++ b/drivers/gpu/drm/i915/display/intel_display_power.c
@@ -341,6 +341,17 @@ static void hsw_wait_for_power_well_enable(struct drm_i915_private *dev_priv,
 {
 	const struct i915_power_well_regs *regs = power_well->desc->hsw.regs;
 	int pw_idx = power_well->desc->hsw.idx;
+	int enable_delay = power_well->desc->hsw.fixed_enable_delay;
+
+	/*
+	 * For some power wells we're not supposed to watch the status bit for
+	 * an ack, but rather just wait a fixed amount of time and then
+	 * proceed.  This is only used on DG2.
+	 */
+	if (IS_DG2(dev_priv) && enable_delay) {
+		usleep_range(enable_delay, 2 * enable_delay);
+		return;
+	}
 
 	/* Timeout for PW1:10 us, AUX:not specified, other PWs:20 us. */
 	if (intel_de_wait_for_set(dev_priv, regs->driver,
@@ -4828,6 +4839,7 @@ static const struct i915_power_well_desc xelpd_power_wells[] = {
 		{
 			.hsw.regs = &icl_aux_power_well_regs,
 			.hsw.idx = ICL_PW_CTL_IDX_AUX_A,
+			.hsw.fixed_enable_delay = 600,
 		},
 	},
 	{
@@ -4838,6 +4850,7 @@ static const struct i915_power_well_desc xelpd_power_wells[] = {
 		{
 			.hsw.regs = &icl_aux_power_well_regs,
 			.hsw.idx = ICL_PW_CTL_IDX_AUX_B,
+			.hsw.fixed_enable_delay = 600,
 		},
 	},
 	{
@@ -4848,6 +4861,7 @@ static const struct i915_power_well_desc xelpd_power_wells[] = {
 		{
 			.hsw.regs = &icl_aux_power_well_regs,
 			.hsw.idx = ICL_PW_CTL_IDX_AUX_C,
+			.hsw.fixed_enable_delay = 600,
 		},
 	},
 	{
@@ -4858,6 +4872,7 @@ static const struct i915_power_well_desc xelpd_power_wells[] = {
 		{
 			.hsw.regs = &icl_aux_power_well_regs,
 			.hsw.idx = XELPD_PW_CTL_IDX_AUX_D,
+			.hsw.fixed_enable_delay = 600,
 		},
 	},
 	{
@@ -4878,6 +4893,7 @@ static const struct i915_power_well_desc xelpd_power_wells[] = {
 		{
 			.hsw.regs = &icl_aux_power_well_regs,
 			.hsw.idx = TGL_PW_CTL_IDX_AUX_TC1,
+			.hsw.fixed_enable_delay = 600,
 		},
 	},
 	{
diff --git a/drivers/gpu/drm/i915/display/intel_display_power.h b/drivers/gpu/drm/i915/display/intel_display_power.h
index 4f0917df4375..22367b5cba96 100644
--- a/drivers/gpu/drm/i915/display/intel_display_power.h
+++ b/drivers/gpu/drm/i915/display/intel_display_power.h
@@ -223,6 +223,12 @@ struct i915_power_well_desc {
 			u8 idx;
 			/* Mask of pipes whose IRQ logic is backed by the pw */
 			u8 irq_pipe_mask;
+			/*
+			 * Instead of waiting for the status bit to ack enables,
+			 * just wait a specific amount of time and then consider
+			 * the well enabled.
+			 */
+			u16 fixed_enable_delay;
 			/* The pw is backing the VGA functionality */
 			bool has_vga:1;
 			bool has_fuses:1;
-- 
2.25.4