[PATCH 06/18] drm/i915/wm: use generic read_poll_timeout() instead of wait_for()

[Jani Nikula]

Prefer generic poll helpers over i915 custom helpers.

The functional change is losing the exponentially growing sleep of
wait_for(), which used to be 10, 20, 40, ..., 640, and 1280 us.

Use an arbitrary constant 500 us sleep instead. The timeout remains at 3
ms.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/display/i9xx_wm.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/i9xx_wm.c b/drivers/gpu/drm/i915/display/i9xx_wm.c
index 1f9db5118777..6a8aa7fcfc2d 100644
--- a/drivers/gpu/drm/i915/display/i9xx_wm.c
+++ b/drivers/gpu/drm/i915/display/i9xx_wm.c
@@ -3,6 +3,8 @@
  * Copyright © 2023 Intel Corporation
  */
 
+#include <linux/iopoll.h>
+
 #include "i915_drv.h"
 #include "i915_reg.h"
 #include "i9xx_wm.h"
@@ -109,6 +111,7 @@ static const struct cxsr_latency *pnv_get_cxsr_latency(struct intel_display *dis
 static void chv_set_memory_dvfs(struct intel_display *display, bool enable)
 {
 	u32 val;
+	int ret;
 
 	vlv_punit_get(display->drm);
 
@@ -121,8 +124,11 @@ static void chv_set_memory_dvfs(struct intel_display *display, bool enable)
 	val |= FORCE_DDR_FREQ_REQ_ACK;
 	vlv_punit_write(display->drm, PUNIT_REG_DDR_SETUP2, val);
 
-	if (wait_for((vlv_punit_read(display->drm, PUNIT_REG_DDR_SETUP2) &
-		      FORCE_DDR_FREQ_REQ_ACK) == 0, 3))
+	ret = read_poll_timeout(vlv_punit_read, val,
+				(val & FORCE_DDR_FREQ_REQ_ACK) == 0,
+				500, 3000, false,
+				display->drm, PUNIT_REG_DDR_SETUP2);
+	if (ret)
 		drm_err(display->drm,
 			"timed out waiting for Punit DDR DVFS request\n");
 
@@ -3902,6 +3908,7 @@ static void vlv_wm_get_hw_state(struct intel_display *display)
 	struct vlv_wm_values *wm = &display->wm.vlv;
 	struct intel_crtc *crtc;
 	u32 val;
+	int ret;
 
 	vlv_read_wm_values(display, wm);
 
@@ -3928,8 +3935,11 @@ static void vlv_wm_get_hw_state(struct intel_display *display)
 		val |= FORCE_DDR_FREQ_REQ_ACK;
 		vlv_punit_write(display->drm, PUNIT_REG_DDR_SETUP2, val);
 
-		if (wait_for((vlv_punit_read(display->drm, PUNIT_REG_DDR_SETUP2) &
-			      FORCE_DDR_FREQ_REQ_ACK) == 0, 3)) {
+		ret = read_poll_timeout(vlv_punit_read, val,
+					(val & FORCE_DDR_FREQ_REQ_ACK) == 0,
+					500, 3000, false,
+					display->drm, PUNIT_REG_DDR_SETUP2);
+		if (ret) {
 			drm_dbg_kms(display->drm,
 				    "Punit not acking DDR DVFS request, "
 				    "assuming DDR DVFS is disabled\n");
-- 
2.39.5