drm/mgag200: Compute PLL values during atomic check

PLL setup can fail if the display mode's clock is not supported by
any PLL configuration. Compute the PLL values during atomic check, so
that atomic commits can fail at the appropriate time. If successful,
use the values in the atomic-update phase.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210714142240.21979-14-tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_drv.h

@@ -159,6 +159,8 @@ struct mgag200_pll {
 
 struct mgag200_crtc_state {
 	struct drm_crtc_state base;
+
+	struct mgag200_pll_values pixpllc;
 };
 
 static inline struct mgag200_crtc_state *to_mgag200_crtc_state(struct drm_crtc_state *base)

drivers/gpu/drm/mgag200/mgag200_mode.c

@@ -110,23 +110,6 @@ static inline void mga_wait_busy(struct mga_device *mdev)
 	} while ((status & 0x01) && time_before(jiffies, timeout));
 }
 
-/*
- * PLL setup
- */
-
-static void mgag200_crtc_set_plls(struct mga_device *mdev, long clock)
-{
-	struct mgag200_pll *pixpll = &mdev->pixpll;
-	struct mgag200_pll_values pixpllc;
-	int ret;
-
-	ret = pixpll->funcs->compute(pixpll, clock, &pixpllc);
-	if (ret)
-		return;
-
-	pixpll->funcs->update(pixpll, &pixpllc);
-}
-
 static void mgag200_g200wb_hold_bmc(struct mga_device *mdev)
 {
 	u8 tmp;
@@ -881,7 +864,9 @@ mgag200_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
 	struct drm_crtc *crtc = &pipe->crtc;
 	struct drm_device *dev = crtc->dev;
 	struct mga_device *mdev = to_mga_device(dev);
+	struct mgag200_pll *pixpll = &mdev->pixpll;
 	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
+	struct mgag200_crtc_state *mgag200_crtc_state = to_mgag200_crtc_state(crtc_state);
 	struct drm_framebuffer *fb = plane_state->fb;
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	struct drm_rect fullscreen = {
@@ -896,7 +881,8 @@ mgag200_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
 
 	mgag200_set_format_regs(mdev, fb);
 	mgag200_set_mode_regs(mdev, adjusted_mode);
-	mgag200_crtc_set_plls(mdev, adjusted_mode->clock);
+
+	pixpll->funcs->update(pixpll, &mgag200_crtc_state->pixpllc);
 
 	if (mdev->type == G200_ER)
 		mgag200_g200er_reset_tagfifo(mdev);
@@ -930,8 +916,13 @@ mgag200_simple_display_pipe_check(struct drm_simple_display_pipe *pipe,
 				  struct drm_crtc_state *crtc_state)
 {
 	struct drm_plane *plane = plane_state->plane;
+	struct drm_device *dev = plane->dev;
+	struct mga_device *mdev = to_mga_device(dev);
+	struct mgag200_pll *pixpll = &mdev->pixpll;
+	struct mgag200_crtc_state *mgag200_crtc_state = to_mgag200_crtc_state(crtc_state);
 	struct drm_framebuffer *new_fb = plane_state->fb;
 	struct drm_framebuffer *fb = NULL;
+	int ret;
 
 	if (!new_fb)
 		return 0;
@@ -942,6 +933,13 @@ mgag200_simple_display_pipe_check(struct drm_simple_display_pipe *pipe,
 	if (!fb || (fb->format != new_fb->format))
 		crtc_state->mode_changed = true; /* update PLL settings */
 
+	if (crtc_state->mode_changed) {
+		ret = pixpll->funcs->compute(pixpll, crtc_state->mode.clock,
+					     &mgag200_crtc_state->pixpllc);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 
@@ -969,6 +967,7 @@ mgag200_simple_display_pipe_duplicate_crtc_state(struct drm_simple_display_pipe
 {
 	struct drm_crtc *crtc = &pipe->crtc;
 	struct drm_crtc_state *crtc_state = crtc->state;
+	struct mgag200_crtc_state *mgag200_crtc_state = to_mgag200_crtc_state(crtc_state);
 	struct mgag200_crtc_state *new_mgag200_crtc_state;
 
 	if (!crtc_state)
@@ -979,6 +978,9 @@ mgag200_simple_display_pipe_duplicate_crtc_state(struct drm_simple_display_pipe
 		return NULL;
 	__drm_atomic_helper_crtc_duplicate_state(crtc, &new_mgag200_crtc_state->base);
 
+	memcpy(&new_mgag200_crtc_state->pixpllc, &mgag200_crtc_state->pixpllc,
+	       sizeof(new_mgag200_crtc_state->pixpllc));
+
 	return &new_mgag200_crtc_state->base;
 }