Re: [RFC v4 22/25] drm/fb-helper: Add generic fbdev emulation

On Sat, Apr 14, 2018 at 01:53:15PM +0200, Noralf Trønnes wrote:

This adds generic fbdev emulation for drivers that supports dumb buffers which they can export.

All the driver has to do is call drm_fbdev_generic_setup().

Signed-off-by: Noralf Trønnes noralf@tronnes.org

drivers/gpu/drm/drm_fb_helper.c | 255 ++++++++++++++++++++++++++++++++++++++++ include/drm/drm_fb_helper.h | 20 ++++ 2 files changed, 275 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index b1124c08b1ed..1954de5b13e0 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -30,6 +30,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/console.h> +#include <linux/dma-buf.h> #include <linux/kernel.h> #include <linux/sysrq.h> #include <linux/slab.h> @@ -1995,6 +1996,260 @@ void drm_fb_helper_output_poll_changed(struct drm_device *dev) } EXPORT_SYMBOL(drm_fb_helper_output_poll_changed);

+static int drm_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma) +{

• struct drm_fb_helper *fb_helper = info->par;
• return dma_buf_mmap(fb_helper->buffer->dma_buf, vma, 0);

+}

+/*

• • fb_ops.fb_destroy is called by the last put_fb_info() call at the end of
• • unregister_framebuffer() or fb_release().
• */

+static void drm_fbdev_fb_destroy(struct fb_info *info) +{

• struct drm_fb_helper *fb_helper = info->par;
• struct fb_ops *fbops = NULL;
• DRM_DEBUG("\n");
• if (fb_helper->fbdev->fbdefio)

• fbops = fb_helper->fbdev->fbops;
  

• drm_fb_helper_fini(fb_helper);
• drm_client_framebuffer_delete(fb_helper->buffer);
• drm_client_free(fb_helper->client);
• kfree(fb_helper);
• kfree(fbops);

+}

+static struct fb_ops drm_fbdev_fb_ops = {

• /*

• * No need to set owner, this module is already pinned by the driver.
  

• * A reference is taken on the driver module in drm_fb_helper_fb_open()
  

• * to prevent the driver going away with open fd's.
  

• */
  

• DRM_FB_HELPER_DEFAULT_OPS,
• .fb_open = drm_fb_helper_fb_open,
• .fb_release = drm_fb_helper_fb_release,
• .fb_destroy = drm_fbdev_fb_destroy,
• .fb_mmap = drm_fbdev_fb_mmap,
• .fb_read = drm_fb_helper_sys_read,
• .fb_write = drm_fb_helper_sys_write,
• .fb_fillrect = drm_fb_helper_sys_fillrect,
• .fb_copyarea = drm_fb_helper_sys_copyarea,
• .fb_imageblit = drm_fb_helper_sys_imageblit,

+};

+static struct fb_deferred_io drm_fbdev_defio = {

• .delay = HZ / 20,
• .deferred_io = drm_fb_helper_deferred_io,

+};

+/* Hack to test tinydrm before converting to vmalloc buffers */ +static int drm_fbdev_cma_deferred_io_mmap(struct fb_info *info,

• 			  struct vm_area_struct *vma)
  

+{

• fb_deferred_io_mmap(info, vma);
• vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
• return 0;

+}

+static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,

• 		       struct drm_fb_helper_surface_size *sizes)
  

+{

• struct drm_client_dev *client = fb_helper->client;
• struct drm_display_mode sizes_mode = {

• .hdisplay = sizes->surface_width,
  

• .vdisplay = sizes->surface_height,
  

• };
• struct drm_client_buffer *buffer;
• struct drm_framebuffer *fb;
• struct fb_info *fbi;
• u32 format;
• int ret;
• DRM_DEBUG_KMS("surface width(%d), height(%d) and bpp(%d)\n",

•       sizes->surface_width, sizes->surface_height,
  

•       sizes->surface_bpp);
  

• format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth);
• buffer = drm_client_framebuffer_create(client, &sizes_mode, format);
• if (IS_ERR(buffer))

• return PTR_ERR(buffer);
  

• fb_helper->buffer = buffer;
• fb_helper->fb = buffer->fb;
• fb = buffer->fb;
• fbi = drm_fb_helper_alloc_fbi(fb_helper);
• if (IS_ERR(fbi)) {

• ret = PTR_ERR(fbi);
  

• goto err_free_buffer;
  

• }
• fbi->par = fb_helper;
• fbi->fbops = &drm_fbdev_fb_ops;
• fbi->screen_size = fb->height * fb->pitches[0];
• fbi->fix.smem_len = fbi->screen_size;
• fbi->screen_buffer = buffer->vaddr;
• strcpy(fbi->fix.id, "DRM emulated");
• drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->format->depth);
• drm_fb_helper_fill_var(fbi, fb_helper, sizes->fb_width, sizes->fb_height);
• /*

• * Drivers that set the dirty callback:
  

• * - Doesn't use defio:
  

• *   i915, virtio, rockchip
  

• * - defio with vmalloc buffer blitted on the real one:
  

• *   vmwgfx
  

• * - defio is disabled because it doesn't work with shmem:
  

• *   udl
  

• * - defio with special dirty callback for fbdev, uses vmalloc for fbdev:
  

• *   qxl
  

• * - defio with cma buffer, will move to vmalloc buffers:
  

• *   tinydrm
  

• *
  

• * TODO:
  

• * Maybe add vmalloc shadow buffer support.
  

• */
  

• if (fb->funcs->dirty) {

• struct fb_ops *fbops;
  

• /*
  

•  * fb_deferred_io_cleanup() clears &fbops->fb_mmap so a per
  

•  * instance version is necessary.
  

•  */
  

• fbops = kzalloc(sizeof(*fbops), GFP_KERNEL);
  

• if (!fbops) {
  

• 	ret = -ENOMEM;
  

• 	goto err_fb_info_destroy;
  

• }
  

• *fbops = *fbi->fbops;
  

• fbi->fbops = fbops;
  

• fbi->fbdefio = &drm_fbdev_defio;
  

• /* Hack so I can test with tinydrm */
  

• fbi->fix.smem_start = page_to_phys(virt_to_page(buffer->vaddr));
  

• fb_deferred_io_init(fbi);
  

• /* Hack so I can test with tinydrm */
  

• fbi->fbops->fb_mmap = drm_fbdev_cma_deferred_io_mmap;
  

• }
• return 0;

+err_fb_info_destroy:

• drm_fb_helper_fini(fb_helper);

+err_free_buffer:

• drm_client_framebuffer_delete(buffer);
• return ret;

+}

I'd split this patch into 2:

- First one just adds the generic_probe callback. We could then start rolling that one out to lots of drivers, which would give all this code lots of testing.

- Second part is the generic client stuff below. Again then with follow-up patches to roll it out.

This way we could achieve a slightly more gradual transition of drivers. And the first step should only be replacing the fb_probe callback. -Daniel

+static const struct drm_fb_helper_funcs drm_fb_helper_generic_funcs = {

• .fb_probe = drm_fb_helper_generic_probe,

+};

+static int drm_fbdev_client_remove(struct drm_client_dev *client) +{

• struct drm_fb_helper *fb_helper = client->private;
• if (!fb_helper->fbdev) {

• kfree(fb_helper);
  

• return 0;
  

• }
• unregister_framebuffer(fb_helper->fbdev);
• /*

• * If userspace is closed the client is now freed by
  

• * drm_fbdev_fb_destroy(), otherwise it will be freed on the last close.
  

• * Return 1 to tell that freeing is taken care of.
  

• */
  

• return 1;

+}

+static int drm_fbdev_client_lastclose(struct drm_client_dev *client) +{

• struct drm_fb_helper *fb_helper = client->private;
• drm_fb_helper_restore_fbdev_mode_unlocked(fb_helper);
• return 0;

+}

+static int drm_fbdev_client_hotplug(struct drm_client_dev *client) +{

• struct drm_fb_helper *fb_helper = client->private;
• if (fb_helper->fbdev)

• return 0;
  

• return drm_fb_helper_fbdev_setup(client->dev, fb_helper,

• 			 &drm_fb_helper_generic_funcs,
  

• 			 fb_helper->preferred_bpp, 0);
  

+}

+static const struct drm_client_funcs drm_fbdev_client_funcs = {

• .name = "fbdev",
• .remove = drm_fbdev_client_remove,
• .lastclose = drm_fbdev_client_lastclose,
• .hotplug = drm_fbdev_client_hotplug,

+};

+/**

• • drm_fb_helper_generic_fbdev_setup() - Setup generic fbdev emulation
• • @dev: DRM device
• • @preferred_bpp: Preferred bits per pixel for the device.

• •             @dev->mode_config.preferred_depth is used if this is zero.
    

• • This function sets up generic fbdev emulation for drivers that supports
• • dumb buffers which can be exported.
• • Restore, hotplug events and teardown are all taken care of. Drivers that does
• • suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves.
• • Simple drivers might use drm_mode_config_helper_suspend().
• • Returns:
• • Zero on success or negative error code on failure.
• */

+int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp) +{

• struct drm_fb_helper *fb_helper;
• struct drm_client_dev *client;
• if (!drm_fbdev_emulation)

• return 0;
  

• fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
• if (!fb_helper)

• return -ENOMEM;
  

• client = drm_client_new(dev, &drm_fbdev_client_funcs);
• if (IS_ERR(client)) {

• kfree(fb_helper);
  

• return PTR_ERR(client);
  

• }
• client->private = fb_helper;
• fb_helper->client = client;
• fb_helper->preferred_bpp = preferred_bpp;
• drm_fbdev_client_hotplug(client);
• return 0;

+} +EXPORT_SYMBOL(drm_fbdev_generic_setup);

/* The Kconfig DRM_KMS_HELPER selects FRAMEBUFFER_CONSOLE (if !EXPERT)

• but the module doesn't depend on any fb console symbols. At least
• attempt to load fbcon to avoid leaving the system without a usable console.

diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h index 330983975d5e..711da1747836 100644 --- a/include/drm/drm_fb_helper.h +++ b/include/drm/drm_fb_helper.h @@ -126,6 +126,20 @@ struct drm_fb_helper { */ struct drm_client_display *display;

• /**

• * @client:
  

• *
  

• * DRM client used by the generic fbdev emulation.
  

• */
  

• struct drm_client_dev *client;
• /**

• * @buffer:
  

• *
  

• * Framebuffer used by the generic fbdev emulation.
  

• */
  

• struct drm_client_buffer *buffer;
• const struct drm_fb_helper_funcs *funcs; struct fb_info *fbdev; u32 pseudo_palette[17];

@@ -219,6 +233,7 @@ struct drm_fb_helper { .fb_ioctl = drm_fb_helper_ioctl

#ifdef CONFIG_DRM_FBDEV_EMULATION +int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp); void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper, const struct drm_fb_helper_funcs *funcs); int drm_fb_helper_init(struct drm_device *dev, @@ -297,6 +312,11 @@ void drm_fb_helper_fbdev_teardown(struct drm_device *dev); void drm_fb_helper_lastclose(struct drm_device *dev); void drm_fb_helper_output_poll_changed(struct drm_device *dev); #else +static inline int +drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp) +{ +}

static inline void drm_fb_helper_prepare(struct drm_device *dev, struct drm_fb_helper *helper, const struct drm_fb_helper_funcs *funcs) -- 2.15.1

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