drm/gma500: Remove GTT roll support

GTT roll support was used to accelerate fb panning on some machines.
Unfortunately this never worked properly with multiple monitors and
caused issues on others where the framebuffer wouldn't fit in stolen
memory. Let's remove it!
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20201028143608.1284-1-patrik.r.jakobsson@gmail.com

drivers/gpu/drm/gma500/framebuffer.c

@@ -76,27 +76,6 @@ static int psbfb_setcolreg(unsigned regno, unsigned red, unsigned green,
 	return 0;
 }
 
-static int psbfb_pan(struct fb_var_screeninfo *var, struct fb_info *info)
-{
-	struct drm_fb_helper *fb_helper = info->par;
-	struct drm_framebuffer *fb = fb_helper->fb;
-	struct drm_device *dev = fb->dev;
-	struct gtt_range *gtt = to_gtt_range(fb->obj[0]);
-
-	/*
-	 *	We have to poke our nose in here. The core fb code assumes
-	 *	panning is part of the hardware that can be invoked before
-	 *	the actual fb is mapped. In our case that isn't quite true.
-	 */
-	if (gtt->npage) {
-		/* GTT roll shifts in 4K pages, we need to shift the right
-		   number of pages */
-		int pages = info->fix.line_length >> 12;
-		psb_gtt_roll(dev, gtt, var->yoffset * pages);
-	}
-        return 0;
-}
-
 static vm_fault_t psbfb_vm_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
@@ -176,17 +155,6 @@ static const struct fb_ops psbfb_ops = {
 	.fb_sync = psbfb_sync,
 };
 
-static const struct fb_ops psbfb_roll_ops = {
-	.owner = THIS_MODULE,
-	DRM_FB_HELPER_DEFAULT_OPS,
-	.fb_setcolreg = psbfb_setcolreg,
-	.fb_fillrect = drm_fb_helper_cfb_fillrect,
-	.fb_copyarea = drm_fb_helper_cfb_copyarea,
-	.fb_imageblit = drm_fb_helper_cfb_imageblit,
-	.fb_pan_display = psbfb_pan,
-	.fb_mmap = psbfb_mmap,
-};
-
 static const struct fb_ops psbfb_unaccel_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
@@ -312,8 +280,6 @@ static int psbfb_create(struct drm_fb_helper *fb_helper,
 	int ret;
 	struct gtt_range *backing;
 	u32 bpp, depth;
-	int gtt_roll = 0;
-	int pitch_lines = 0;
 
 	mode_cmd.width = sizes->surface_width;
 	mode_cmd.height = sizes->surface_height;
@@ -324,50 +290,15 @@ static int psbfb_create(struct drm_fb_helper *fb_helper,
 	if (bpp == 24)
 		bpp = 32;
 
-	do {
-		/*
-		 * Acceleration via the GTT requires pitch to be
-		 * power of two aligned. Preferably page but less
-		 * is ok with some fonts
-		 */
-        	mode_cmd.pitches[0] =  ALIGN(mode_cmd.width * ((bpp + 7) / 8), 4096 >> pitch_lines);
-
-        	size = mode_cmd.pitches[0] * mode_cmd.height;
-        	size = ALIGN(size, PAGE_SIZE);
-
-		/* Allocate the fb in the GTT with stolen page backing */
-		backing = psbfb_alloc(dev, size);
-
-		if (pitch_lines)
-			pitch_lines *= 2;
-		else
-			pitch_lines = 1;
-		gtt_roll++;
-	} while (backing == NULL && pitch_lines <= 16);
-
-	/* The final pitch we accepted if we succeeded */
-	pitch_lines /= 2;
-
-	if (backing == NULL) {
-		/*
-		 *	We couldn't get the space we wanted, fall back to the
-		 *	display engine requirement instead.  The HW requires
-		 *	the pitch to be 64 byte aligned
-		 */
-
-		gtt_roll = 0;	/* Don't use GTT accelerated scrolling */
-		pitch_lines = 64;
-
-		mode_cmd.pitches[0] =  ALIGN(mode_cmd.width * ((bpp + 7) / 8), 64);
-
-		size = mode_cmd.pitches[0] * mode_cmd.height;
-		size = ALIGN(size, PAGE_SIZE);
-
-		/* Allocate the framebuffer in the GTT with stolen page backing */
-		backing = psbfb_alloc(dev, size);
-		if (backing == NULL)
-			return -ENOMEM;
-	}
+	mode_cmd.pitches[0] = ALIGN(mode_cmd.width * DIV_ROUND_UP(bpp, 8), 64);
+
+	size = mode_cmd.pitches[0] * mode_cmd.height;
+	size = ALIGN(size, PAGE_SIZE);
+
+	/* Allocate the framebuffer in the GTT with stolen page backing */
+	backing = psbfb_alloc(dev, size);
+	if (backing == NULL)
+		return -ENOMEM;
 
 	memset(dev_priv->vram_addr + backing->offset, 0, size);
 
@@ -387,17 +318,14 @@ static int psbfb_create(struct drm_fb_helper *fb_helper,
 
 	fb_helper->fb = fb;
 
-	if (dev_priv->ops->accel_2d && pitch_lines > 8)	/* 2D engine */
+	if (dev_priv->ops->accel_2d)	/* 2D engine */
 		info->fbops = &psbfb_ops;
-	else if (gtt_roll) {	/* GTT rolling seems best */
-		info->fbops = &psbfb_roll_ops;
-		info->flags |= FBINFO_HWACCEL_YPAN;
-	} else	/* Software */
+	else	/* Software */
 		info->fbops = &psbfb_unaccel_ops;
 
 	info->fix.smem_start = dev->mode_config.fb_base;
 	info->fix.smem_len = size;
-	info->fix.ywrapstep = gtt_roll;
+	info->fix.ywrapstep = 0;
 	info->fix.ypanstep = 0;
 
 	/* Accessed stolen memory directly */

drivers/gpu/drm/gma500/gtt.c

@@ -96,16 +96,12 @@ static int psb_gtt_insert(struct drm_device *dev, struct gtt_range *r,
 	}
 
 	/* Write our page entries into the GTT itself */
-	for (i = r->roll; i < r->npage; i++) {
-		pte = psb_gtt_mask_pte(page_to_pfn(r->pages[i]),
-				       PSB_MMU_CACHED_MEMORY);
-		iowrite32(pte, gtt_slot++);
-	}
-	for (i = 0; i < r->roll; i++) {
+	for (i = 0; i < r->npage; i++) {
 		pte = psb_gtt_mask_pte(page_to_pfn(r->pages[i]),
 				       PSB_MMU_CACHED_MEMORY);
 		iowrite32(pte, gtt_slot++);
 	}
+
 	/* Make sure all the entries are set before we return */
 	ioread32(gtt_slot - 1);
 
@@ -140,49 +136,6 @@ static void psb_gtt_remove(struct drm_device *dev, struct gtt_range *r)
 	set_pages_array_wb(r->pages, r->npage);
 }
 
-/**
- *	psb_gtt_roll	-	set scrolling position
- *	@dev: our DRM device
- *	@r: the gtt mapping we are using
- *	@roll: roll offset
- *
- *	Roll an existing pinned mapping by moving the pages through the GTT.
- *	This allows us to implement hardware scrolling on the consoles without
- *	a 2D engine
- */
-void psb_gtt_roll(struct drm_device *dev, struct gtt_range *r, int roll)
-{
-	u32 __iomem *gtt_slot;
-	u32 pte;
-	int i;
-
-	if (roll >= r->npage) {
-		WARN_ON(1);
-		return;
-	}
-
-	r->roll = roll;
-
-	/* Not currently in the GTT - no worry we will write the mapping at
-	   the right position when it gets pinned */
-	if (!r->stolen && !r->in_gart)
-		return;
-
-	gtt_slot = psb_gtt_entry(dev, r);
-
-	for (i = r->roll; i < r->npage; i++) {
-		pte = psb_gtt_mask_pte(page_to_pfn(r->pages[i]),
-				       PSB_MMU_CACHED_MEMORY);
-		iowrite32(pte, gtt_slot++);
-	}
-	for (i = 0; i < r->roll; i++) {
-		pte = psb_gtt_mask_pte(page_to_pfn(r->pages[i]),
-				       PSB_MMU_CACHED_MEMORY);
-		iowrite32(pte, gtt_slot++);
-	}
-	ioread32(gtt_slot - 1);
-}
-
 /**
  *	psb_gtt_attach_pages	-	attach and pin GEM pages
  *	@gt: the gtt range
@@ -346,7 +299,6 @@ struct gtt_range *psb_gtt_alloc_range(struct drm_device *dev, int len,
 	gt->resource.name = name;
 	gt->stolen = backed;
 	gt->in_gart = backed;
-	gt->roll = 0;
 	/* Ensure this is set for non GEM objects */
 	gt->gem.dev = dev;
 	ret = allocate_resource(dev_priv->gtt_mem, &gt->resource,

drivers/gpu/drm/gma500/gtt.h

@@ -37,7 +37,6 @@ struct gtt_range {
 	bool mmapping;			/* Is mmappable */
 	struct page **pages;		/* Backing pages if present */
 	int npage;			/* Number of backing pages */
-	int roll;			/* Roll applied to the GTT entries */
 };
 
 #define to_gtt_range(x) container_of(x, struct gtt_range, gem)
@@ -49,7 +48,5 @@ extern void psb_gtt_kref_put(struct gtt_range *gt);
 extern void psb_gtt_free_range(struct drm_device *dev, struct gtt_range *gt);
 extern int psb_gtt_pin(struct gtt_range *gt);
 extern void psb_gtt_unpin(struct gtt_range *gt);
-extern void psb_gtt_roll(struct drm_device *dev,
-					struct gtt_range *gt, int roll);
 extern int psb_gtt_restore(struct drm_device *dev);
 #endif