drm/gma500: Add page flip support on psb/cdv

Legacy (non-atomic) page flip support is added to the driver by using the
mode_set_base CRTC function, that allows configuring a new framebuffer for
display. Since the function requires the primary plane's fb to be set
already, this is done prior to calling the function in the page flip helper
and reverted if the flip fails.

The vblank interrupt handler is also refactored to support passing an event.
The PIPE_TE_STATUS bit is also considered to indicate vblank on medfield
only, as explained in psb_enable_vblank.

It was tested by running weston on both poulsbo and cedartrail.

Signed-off-by: Paul Kocialkowski <[e-mail]>
Reviewed-by: Patrik Jakobsson <[e-mail]>
Signed-off-by: Patrik Jakobsson <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/gma500/cdv_intel_display.c

···
 	.gamma_set = gma_crtc_gamma_set,
 	.set_config = gma_crtc_set_config,
 	.destroy = gma_crtc_destroy,
+	.page_flip = gma_crtc_page_flip,
 };
 
 const struct gma_clock_funcs cdv_clock_funcs = {

drivers/gpu/drm/gma500/gma_display.c

···
 	kfree(gma_crtc);
 }
 
+int gma_crtc_page_flip(struct drm_crtc *crtc,
+		       struct drm_framebuffer *fb,
+		       struct drm_pending_vblank_event *event,
+		       uint32_t page_flip_flags,
+		       struct drm_modeset_acquire_ctx *ctx)
+{
+	struct gma_crtc *gma_crtc = to_gma_crtc(crtc);
+	struct drm_framebuffer *current_fb = crtc->primary->fb;
+	struct drm_framebuffer *old_fb = crtc->primary->old_fb;
+	const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
+	struct drm_device *dev = crtc->dev;
+	unsigned long flags;
+	int ret;
+
+	if (!crtc_funcs->mode_set_base)
+		return -EINVAL;
+
+	/* Using mode_set_base requires the new fb to be set already. */
+	crtc->primary->fb = fb;
+
+	if (event) {
+		spin_lock_irqsave(&dev->event_lock, flags);
+
+		WARN_ON(drm_crtc_vblank_get(crtc) != 0);
+
+		gma_crtc->page_flip_event = event;
+
+		/* Call this locked if we want an event at vblank interrupt. */
+		ret = crtc_funcs->mode_set_base(crtc, crtc->x, crtc->y, old_fb);
+		if (ret) {
+			gma_crtc->page_flip_event = NULL;
+			drm_crtc_vblank_put(crtc);
+		}
+
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+	} else {
+		ret = crtc_funcs->mode_set_base(crtc, crtc->x, crtc->y, old_fb);
+	}
+
+	/* Restore previous fb in case of failure. */
+	if (ret)
+		crtc->primary->fb = current_fb;
+
+	return ret;
+}
+
 int gma_crtc_set_config(struct drm_mode_set *set,
 			struct drm_modeset_acquire_ctx *ctx)
 {

drivers/gpu/drm/gma500/gma_display.h

···
 #define _GMA_DISPLAY_H_
 
 #include <linux/pm_runtime.h>
+#include <drm/drm_vblank.h>
 
 struct drm_encoder;
 struct drm_mode_set;
···
 extern void gma_crtc_commit(struct drm_crtc *crtc);
 extern void gma_crtc_disable(struct drm_crtc *crtc);
 extern void gma_crtc_destroy(struct drm_crtc *crtc);
+extern int gma_crtc_page_flip(struct drm_crtc *crtc,
+			      struct drm_framebuffer *fb,
+			      struct drm_pending_vblank_event *event,
+			      uint32_t page_flip_flags,
+			      struct drm_modeset_acquire_ctx *ctx);
 extern int gma_crtc_set_config(struct drm_mode_set *set,
 			       struct drm_modeset_acquire_ctx *ctx);
 

drivers/gpu/drm/gma500/psb_intel_display.c

···
 	.gamma_set = gma_crtc_gamma_set,
 	.set_config = gma_crtc_set_config,
 	.destroy = gma_crtc_destroy,
+	.page_flip = gma_crtc_page_flip,
 };
 
 const struct gma_clock_funcs psb_clock_funcs = {

drivers/gpu/drm/gma500/psb_intel_drv.h

···
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_vblank.h>
 #include <linux/gpio.h>
 #include "gma_display.h"
 
···
 	struct psb_intel_crtc_state *crtc_state;
 
 	const struct gma_clock_funcs *clock_funcs;
+
+	struct drm_pending_vblank_event *page_flip_event;
 };
 
 #define to_gma_crtc(x)	\

drivers/gpu/drm/gma500/psb_irq.c

···
 		"%s, can't clear status bits for pipe %d, its value = 0x%x.\n",
 		__func__, pipe, PSB_RVDC32(pipe_stat_reg));
 
-	if (pipe_stat_val & PIPE_VBLANK_STATUS)
+	if (pipe_stat_val & PIPE_VBLANK_STATUS ||
+	    (IS_MFLD(dev) && pipe_stat_val & PIPE_TE_STATUS)) {
+		struct drm_crtc *crtc = drm_crtc_from_index(dev, pipe);
+		struct gma_crtc *gma_crtc = to_gma_crtc(crtc);
+		unsigned long flags;
+
 		drm_handle_vblank(dev, pipe);
 
-	if (pipe_stat_val & PIPE_TE_STATUS)
-		drm_handle_vblank(dev, pipe);
+		spin_lock_irqsave(&dev->event_lock, flags);
+		if (gma_crtc->page_flip_event) {
+			drm_crtc_send_vblank_event(crtc,
+						   gma_crtc->page_flip_event);
+			gma_crtc->page_flip_event = NULL;
+			drm_crtc_vblank_put(crtc);
+		}
+		spin_unlock_irqrestore(&dev->event_lock, flags);
+	}
 }
 
 /*