drm/mgag200: Don't write-protect CRTC 0-7 while in mga_crtc_prepare()

The prepare function write-protects several registers that it doesn't
even touch. Removed the related code.

The code for unprotecting registers also clears VINT interrupts. Both
is now done once during initialization.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200707082411.6583-2-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_drv.h

@@ -60,6 +60,12 @@
 		WREG8(MGAREG_SEQ_DATA, v);			\
 	} while (0)						\
 
+#define RREG_CRT(reg, v)					\
+	do {							\
+		WREG8(MGAREG_CRTC_INDEX, reg);			\
+		v = RREG8(MGAREG_CRTC_DATA);			\
+	} while (0)						\
+
 #define WREG_CRT(reg, v)					\
 	do {							\
 		WREG8(MGAREG_CRTC_INDEX, reg);			\

drivers/gpu/drm/mgag200/mgag200_mode.c

@@ -988,7 +988,7 @@ static void mgag200_set_dac_regs(struct mga_device *mdev)
 
 static void mgag200_init_regs(struct mga_device *mdev)
 {
-	u8 crtcext3, crtcext4, misc;
+	u8 crtc11, crtcext3, crtcext4, misc;
 
 	mgag200_set_pci_regs(mdev);
 	mgag200_set_dac_regs(mdev);
@@ -1012,6 +1012,12 @@ static void mgag200_init_regs(struct mga_device *mdev)
 	WREG_ECRT(0x03, crtcext3);
 	WREG_ECRT(0x04, crtcext4);
 
+	RREG_CRT(0x11, crtc11);
+	crtc11 &= ~(MGAREG_CRTC11_CRTCPROTECT |
+		    MGAREG_CRTC11_VINTEN |
+		    MGAREG_CRTC11_VINTCLR);
+	WREG_CRT(0x11, crtc11);
+
 	if (mdev->type == G200_ER)
 		WREG_ECRT(0x24, 0x5);
 
@@ -1337,12 +1343,6 @@ static void mga_crtc_prepare(struct drm_crtc *crtc)
 	struct mga_device *mdev = to_mga_device(dev);
 	u8 tmp;
 
-	/*	mga_resume(crtc);*/
-
-	WREG8(MGAREG_CRTC_INDEX, 0x11);
-	tmp = RREG8(MGAREG_CRTC_DATA);
-	WREG_CRT(0x11, tmp | 0x80);
-
 	if (mdev->type == G200_SE_A || mdev->type == G200_SE_B) {
 		WREG_SEQ(0, 1);
 		msleep(50);
@@ -1359,8 +1359,6 @@ static void mga_crtc_prepare(struct drm_crtc *crtc)
 
 	if (mdev->type == G200_WB || mdev->type == G200_EW3)
 		mga_g200wb_prepare(crtc);
-
-	WREG_CRT(17, 0);
 }
 
 /*

drivers/gpu/drm/mgag200/mgag200_reg.h

@@ -240,6 +240,11 @@
 
 #define MGAREG_CRTC_INDEX	0x1fd4
 #define MGAREG_CRTC_DATA	0x1fd5
+
+#define MGAREG_CRTC11_VINTCLR		BIT(4)
+#define MGAREG_CRTC11_VINTEN		BIT(5)
+#define MGAREG_CRTC11_CRTCPROTECT	BIT(7)
+
 #define MGAREG_CRTCEXT_INDEX	0x1fde
 #define MGAREG_CRTCEXT_DATA	0x1fdf