drm/mgag200: Only set VIDRST bits in CRTC modesetting

The VRSTEN and HRSTEN bits control whether a CRTC synchronizes its
display signal with an external source on the VIDRST pin. The G200WB
and G200EW3 models synchronize with a BMC chip, but different external
video encoders, such as the Matrox Maven, can also be attached to the
pin.

Only set VRSTEN and HRSTEN bits in the CRTC mode-setting code, so the
bits are independent from the BMC. Add the field set_vidrst to the CRTC
state for this purpose. Off by default, control the CRTC VIDRST setting
from the CRTC's atomic_check helper.

v3:
- don't clear bits unnecessary (Jocelyn)
v2:
- keep logic entirely in CRTC (Jocelyn)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240711072415.11831-2-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_bmc.c

@@ -77,11 +77,6 @@ void mgag200_bmc_enable_vidrst(struct mga_device *mdev)
 {
 	u8 tmp;
 
-	/* Ensure that the vrsten and hrsten are set */
-	WREG8(MGAREG_CRTCEXT_INDEX, 1);
-	tmp = RREG8(MGAREG_CRTCEXT_DATA);
-	WREG8(MGAREG_CRTCEXT_DATA, tmp | 0x88);
-
 	/* Assert rstlvl2 */
 	WREG8(DAC_INDEX, MGA1064_REMHEADCTL2);
 	tmp = RREG8(DAC_DATA);

drivers/gpu/drm/mgag200/mgag200_drv.h

@@ -179,6 +179,8 @@ struct mgag200_crtc_state {
 	const struct drm_format_info *format;
 
 	struct mgag200_pll_values pixpllc;
+
+	bool set_vidrst;
 };
 
 static inline struct mgag200_crtc_state *to_mgag200_crtc_state(struct drm_crtc_state *base)
@@ -430,7 +432,8 @@ void mgag200_crtc_atomic_destroy_state(struct drm_crtc *crtc, struct drm_crtc_st
 	.atomic_duplicate_state = mgag200_crtc_atomic_duplicate_state, \
 	.atomic_destroy_state = mgag200_crtc_atomic_destroy_state
 
-void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode);
+void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode,
+			   bool set_vidrst);
 void mgag200_set_format_regs(struct mga_device *mdev, const struct drm_format_info *format);
 void mgag200_enable_display(struct mga_device *mdev);
 void mgag200_init_registers(struct mga_device *mdev);

drivers/gpu/drm/mgag200/mgag200_g200er.c

@@ -195,7 +195,7 @@ static void mgag200_g200er_crtc_helper_atomic_enable(struct drm_crtc *crtc,
 		funcs->disable_vidrst(mdev);
 
 	mgag200_set_format_regs(mdev, format);
-	mgag200_set_mode_regs(mdev, adjusted_mode);
+	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
 
 	if (funcs->pixpllc_atomic_update)
 		funcs->pixpllc_atomic_update(crtc, old_state);

drivers/gpu/drm/mgag200/mgag200_g200ev.c

@@ -196,7 +196,7 @@ static void mgag200_g200ev_crtc_helper_atomic_enable(struct drm_crtc *crtc,
 		funcs->disable_vidrst(mdev);
 
 	mgag200_set_format_regs(mdev, format);
-	mgag200_set_mode_regs(mdev, adjusted_mode);
+	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
 
 	if (funcs->pixpllc_atomic_update)
 		funcs->pixpllc_atomic_update(crtc, old_state);

drivers/gpu/drm/mgag200/mgag200_g200se.c

@@ -327,7 +327,7 @@ static void mgag200_g200se_crtc_helper_atomic_enable(struct drm_crtc *crtc,
 		funcs->disable_vidrst(mdev);
 
 	mgag200_set_format_regs(mdev, format);
-	mgag200_set_mode_regs(mdev, adjusted_mode);
+	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
 
 	if (funcs->pixpllc_atomic_update)
 		funcs->pixpllc_atomic_update(crtc, old_state);

drivers/gpu/drm/mgag200/mgag200_mode.c

@@ -201,9 +201,9 @@ void mgag200_init_registers(struct mga_device *mdev)
 	WREG8(MGA_MISC_OUT, misc);
 }
 
-void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode)
+void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mode *mode,
+			   bool set_vidrst)
 {
-	const struct mgag200_device_info *info = mdev->info;
 	unsigned int hdisplay, hsyncstart, hsyncend, htotal;
 	unsigned int vdisplay, vsyncstart, vsyncend, vtotal;
 	u8 misc, crtcext1, crtcext2, crtcext5;
@@ -238,7 +238,7 @@ void mgag200_set_mode_regs(struct mga_device *mdev, const struct drm_display_mod
 		   ((hdisplay & 0x100) >> 7) |
 		   ((hsyncstart & 0x100) >> 6) |
 		    (htotal & 0x40);
-	if (info->has_vidrst)
+	if (set_vidrst)
 		crtcext1 |= MGAREG_CRTCEXT1_VRSTEN |
 			    MGAREG_CRTCEXT1_HRSTEN;
 
@@ -597,6 +597,7 @@ int mgag200_crtc_helper_atomic_check(struct drm_crtc *crtc, struct drm_atomic_st
 	struct mga_device *mdev = to_mga_device(dev);
 	const struct mgag200_device_funcs *funcs = mdev->funcs;
 	struct drm_crtc_state *new_crtc_state = drm_atomic_get_new_crtc_state(new_state, crtc);
+	struct mgag200_crtc_state *new_mgag200_crtc_state = to_mgag200_crtc_state(new_crtc_state);
 	struct drm_property_blob *new_gamma_lut = new_crtc_state->gamma_lut;
 	int ret;
 
@@ -607,6 +608,8 @@ int mgag200_crtc_helper_atomic_check(struct drm_crtc *crtc, struct drm_atomic_st
 	if (ret)
 		return ret;
 
+	new_mgag200_crtc_state->set_vidrst = mdev->info->has_vidrst;
+
 	if (new_crtc_state->mode_changed) {
 		if (funcs->pixpllc_atomic_check) {
 			ret = funcs->pixpllc_atomic_check(crtc, new_state);
@@ -656,7 +659,7 @@ void mgag200_crtc_helper_atomic_enable(struct drm_crtc *crtc, struct drm_atomic_
 		funcs->disable_vidrst(mdev);
 
 	mgag200_set_format_regs(mdev, format);
-	mgag200_set_mode_regs(mdev, adjusted_mode);
+	mgag200_set_mode_regs(mdev, adjusted_mode, mgag200_crtc_state->set_vidrst);
 
 	if (funcs->pixpllc_atomic_update)
 		funcs->pixpllc_atomic_update(crtc, old_state);
@@ -717,6 +720,7 @@ struct drm_crtc_state *mgag200_crtc_atomic_duplicate_state(struct drm_crtc *crtc
 	new_mgag200_crtc_state->format = mgag200_crtc_state->format;
 	memcpy(&new_mgag200_crtc_state->pixpllc, &mgag200_crtc_state->pixpllc,
 	       sizeof(new_mgag200_crtc_state->pixpllc));
+	new_mgag200_crtc_state->set_vidrst = mgag200_crtc_state->set_vidrst;
 
 	return &new_mgag200_crtc_state->base;
 }