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drm/fb-helper: Mark screen buffers in system memory with FB_VIRTFB

PATCH New Thomas Zimmermann 1 participant 1 message Feb 1, 2022

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Stable branch DRM drivers DRM misc
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Thomas Zimmermann

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PATCH v2 1/1 drm/fb-helper: Mark screen buffers in system memory with FB_VIRTFB

Mark screen buffers in system memory with FB_VIRTFB. Otherwise, fbdev deferred I/O marks mmap'ed areas of system memory with VM_IO. (There's an inverse relation ship between the two flags.)

For shadow buffers, also set the FB_READS_FAST hint.

v2:
* updated commit description (Daniel)
* added Fixes tag

Signed-off-by Thomas Zimmermann <[email protected]>
Fixes d536540f304c ("drm/fb-helper: Add generic fbdev emulation .fb_probe function")
Reviewed-by Daniel Vetter <[email protected]>
Cc [email protected]
Cc <[email protected]> # v4.19+
---
 drivers/gpu/drm/drm_fb_helper.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)
drivers/gpu/drm/drm_fb_helper.c +6 -3
index ed43b987d306..f15127a32f7a 100644
@@ -2346,6 +2346,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
 	fbi->fbops = &drm_fbdev_fb_ops;
 	fbi->screen_size = sizes->surface_height * fb->pitches[0];
 	fbi->fix.smem_len = fbi->screen_size;
+	fbi->flags = FBINFO_DEFAULT;
 
 	drm_fb_helper_fill_info(fbi, fb_helper, sizes);
 

@@ -2353,19 +2354,21 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
 		fbi->screen_buffer = vzalloc(fbi->screen_size);
 		if (!fbi->screen_buffer)
 			return -ENOMEM;
+		fbi->flags |= FBINFO_VIRTFB | FBINFO_READS_FAST;
 
 		fbi->fbdefio = &drm_fbdev_defio;
-
 		fb_deferred_io_init(fbi);
 	} else {
 		/* buffer is mapped for HW framebuffer */
 		ret = drm_client_buffer_vmap(fb_helper->buffer, &map);
 		if (ret)
 			return ret;
-		if (map.is_iomem)
+		if (map.is_iomem) {
 			fbi->screen_base = map.vaddr_iomem;
-		else
+		} else {
 			fbi->screen_buffer = map.vaddr;
+			fbi->flags |= FBINFO_VIRTFB;
+		}
 
 		/*
 		 * Shamelessly leak the physical address to user-space. As
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2.34.1