Commit 5a498d4d authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

drm/fbdev-dma: Only install deferred I/O if necessary 



Deferred I/O requires struct page for framebuffer memory, which is
not guaranteed for all DMA ranges. We thus only install deferred I/O
if we have a framebuffer that requires it.

A reported bug affected the ipu-v3 and pl111 drivers, which have video
memory in either Normal or HighMem zones

[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000010000000-0x000000003fffffff]
[    0.000000]   HighMem  [mem 0x0000000040000000-0x000000004fffffff]

where deferred I/O only works correctly with HighMem. See the Closes
tags for bug reports.

v2:
- test if screen_buffer supports deferred I/O (Sima)

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Fixes: 808a40b6 ("drm/fbdev-dma: Implement damage handling and deferred I/O")
Reported-by: default avatarAlexander Stein <alexander.stein@ew.tq-group.com>
Closes: https://lore.kernel.org/all/23636953.6Emhk5qWAg@steina-w/


Reported-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Closes: https://lore.kernel.org/dri-devel/CACRpkdb+hb9AGavbWpY-=uQQ0apY9en_tWJioPKf_fAbXMP4Hg@mail.gmail.com/


Tested-by: default avatarAlexander Stein <alexander.stein@ew.tq-group.com>
Tested-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Reviewed-by: default avatarSimona Vetter <simona.vetter@ffwll.ch>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240904123750.31206-1-tzimmermann@suse.de
parent 7de295d1

drivers/gpu/drm/drm_fbdev_dma.c

+64 −19
Original line number Diff line number Diff line
@@ -36,20 +36,11 @@ static int drm_fbdev_dma_fb_release(struct fb_info *info, int user) 
	return 0;

}



FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS(drm_fbdev_dma,

				   drm_fb_helper_damage_range,

				   drm_fb_helper_damage_area);



static int drm_fbdev_dma_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)

{

	struct drm_fb_helper *fb_helper = info->par;

	struct drm_framebuffer *fb = fb_helper->fb;

	struct drm_gem_dma_object *dma = drm_fb_dma_get_gem_obj(fb, 0);



	if (!dma->map_noncoherent)

		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);



	return fb_deferred_io_mmap(info, vma);

	return drm_gem_prime_mmap(fb_helper->buffer->gem, vma);

}



static void drm_fbdev_dma_fb_destroy(struct fb_info *info)
@@ -70,13 +61,40 @@ static void drm_fbdev_dma_fb_destroy(struct fb_info *info) 
}



static const struct fb_ops drm_fbdev_dma_fb_ops = {

	.owner = THIS_MODULE,

	.fb_open = drm_fbdev_dma_fb_open,

	.fb_release = drm_fbdev_dma_fb_release,

	__FB_DEFAULT_DMAMEM_OPS_RDWR,

	DRM_FB_HELPER_DEFAULT_OPS,

	__FB_DEFAULT_DMAMEM_OPS_DRAW,

	.fb_mmap = drm_fbdev_dma_fb_mmap,

	.fb_destroy = drm_fbdev_dma_fb_destroy,

};



FB_GEN_DEFAULT_DEFERRED_DMAMEM_OPS(drm_fbdev_dma,

				   drm_fb_helper_damage_range,

				   drm_fb_helper_damage_area);



static int drm_fbdev_dma_deferred_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)

{

	struct drm_fb_helper *fb_helper = info->par;

	struct drm_framebuffer *fb = fb_helper->fb;

	struct drm_gem_dma_object *dma = drm_fb_dma_get_gem_obj(fb, 0);



	if (!dma->map_noncoherent)

		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);



	return fb_deferred_io_mmap(info, vma);

}



static const struct fb_ops drm_fbdev_dma_deferred_fb_ops = {

	.owner = THIS_MODULE,

	.fb_open = drm_fbdev_dma_fb_open,

	.fb_release = drm_fbdev_dma_fb_release,

	__FB_DEFAULT_DEFERRED_OPS_RDWR(drm_fbdev_dma),

	DRM_FB_HELPER_DEFAULT_OPS,

	__FB_DEFAULT_DEFERRED_OPS_DRAW(drm_fbdev_dma),

	.fb_mmap = drm_fbdev_dma_fb_mmap,

	.fb_mmap = drm_fbdev_dma_deferred_fb_mmap,

	.fb_destroy = drm_fbdev_dma_fb_destroy,

};
@@ -89,6 +107,7 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, 
{

	struct drm_client_dev *client = &fb_helper->client;

	struct drm_device *dev = fb_helper->dev;

	bool use_deferred_io = false;

	struct drm_client_buffer *buffer;

	struct drm_gem_dma_object *dma_obj;

	struct drm_framebuffer *fb;
@@ -111,6 +130,15 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, 


	fb = buffer->fb;



	/*

	 * Deferred I/O requires struct page for framebuffer memory,

	 * which is not guaranteed for all DMA ranges. We thus only

	 * install deferred I/O if we have a framebuffer that requires

	 * it.

	 */

	if (fb->funcs->dirty)

		use_deferred_io = true;



	ret = drm_client_buffer_vmap(buffer, &map);

	if (ret) {

		goto err_drm_client_buffer_delete;
@@ -130,6 +158,9 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, 


	drm_fb_helper_fill_info(info, fb_helper, sizes);



	if (use_deferred_io)

		info->fbops = &drm_fbdev_dma_deferred_fb_ops;

	else

		info->fbops = &drm_fbdev_dma_fb_ops;



	/* screen */
@@ -144,7 +175,20 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, 
	}

	info->fix.smem_len = info->screen_size;



	/*

	 * Only set up deferred I/O if the screen buffer supports

	 * it. If this disagrees with the previous test for ->dirty,

	 * mmap on the /dev/fb file might not work correctly.

	 */

	if (!is_vmalloc_addr(info->screen_buffer) && info->fix.smem_start) {

		unsigned long pfn = info->fix.smem_start >> PAGE_SHIFT;



		if (drm_WARN_ON(dev, !pfn_to_page(pfn)))

			use_deferred_io = false;

	}



	/* deferred I/O */

	if (use_deferred_io) {

		fb_helper->fbdefio.delay = HZ / 20;

		fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io;
@@ -152,6 +196,7 @@ static int drm_fbdev_dma_helper_fb_probe(struct drm_fb_helper *fb_helper, 
		ret = fb_deferred_io_init(info);

		if (ret)

			goto err_drm_fb_helper_release_info;

	}



	return 0;