[RFC v3 11/12] drm/client: Add bootsplash client
Daniel Vetter
daniel at ffwll.ch
Tue Mar 6 09:12:55 UTC 2018
On Thu, Feb 22, 2018 at 09:06:52PM +0100, Noralf Trønnes wrote:
> Just a hack to test the client API.
>
> Signed-off-by: Noralf Trønnes <noralf at tronnes.org>
Adding the suse folks who submitted the bootsplash a while ago, would be
great if they could pick this up and run with it.
> ---
> drivers/gpu/drm/client/Kconfig | 5 +
> drivers/gpu/drm/client/Makefile | 1 +
> drivers/gpu/drm/client/drm_bootsplash.c | 205 ++++++++++++++++++++++++++++++++
> 3 files changed, 211 insertions(+)
> create mode 100644 drivers/gpu/drm/client/drm_bootsplash.c
>
> diff --git a/drivers/gpu/drm/client/Kconfig b/drivers/gpu/drm/client/Kconfig
> index 73902ab44c75..16cf1e14620a 100644
> --- a/drivers/gpu/drm/client/Kconfig
> +++ b/drivers/gpu/drm/client/Kconfig
> @@ -17,4 +17,9 @@ config DRM_CLIENT_FBDEV
> help
> Generic fbdev emulation
>
> +config DRM_CLIENT_BOOTSPLASH
> + tristate "DRM Bootsplash"
> + help
> + DRM Bootsplash
> +
> endmenu
> diff --git a/drivers/gpu/drm/client/Makefile b/drivers/gpu/drm/client/Makefile
> index 3ff694429dec..8660530e4646 100644
> --- a/drivers/gpu/drm/client/Makefile
> +++ b/drivers/gpu/drm/client/Makefile
> @@ -1,3 +1,4 @@
> # SPDX-License-Identifier: GPL-2.0
>
> obj-$(CONFIG_DRM_CLIENT_FBDEV) += drm_fbdev.o
> +obj-$(CONFIG_DRM_CLIENT_BOOTSPLASH) += drm_bootsplash.o
> diff --git a/drivers/gpu/drm/client/drm_bootsplash.c b/drivers/gpu/drm/client/drm_bootsplash.c
> new file mode 100644
> index 000000000000..43c703606e74
> --- /dev/null
> +++ b/drivers/gpu/drm/client/drm_bootsplash.c
> @@ -0,0 +1,205 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/workqueue.h>
> +
> +#include <drm/drm_client.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_fourcc.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_print.h>
> +
> +struct drm_bootsplash {
> + struct drm_client_dev *client;
> + struct drm_client_display *display;
> + struct drm_client_buffer *buffer[2];
> + struct work_struct worker;
> + bool stop;
> +};
> +
> +static u32 drm_bootsplash_color_table[3] = {
> + 0x00ff0000, 0x0000ff00, 0x000000ff,
> +};
> +
> +/* Draw a box with changing colors */
> +static void
> +drm_bootsplash_draw(struct drm_client_buffer *buffer, unsigned int sequence)
> +{
> + unsigned int x, y;
> + u32 *pix;
> +
> + pix = buffer->vaddr;
> + pix += ((buffer->height / 2) - 50) * buffer->width;
> + pix += (buffer->width / 2) - 50;
> +
> + for (y = 0; y < 100; y++) {
> + for (x = 0; x < 100; x++)
> + *pix++ = drm_bootsplash_color_table[sequence];
> + pix += buffer->width - 100;
> + }
> +}
> +
> +static void drm_bootsplash_worker(struct work_struct *work)
> +{
> + struct drm_bootsplash *splash = container_of(work, struct drm_bootsplash,
> + worker);
> + struct drm_event *event;
> + unsigned int i = 0, sequence = 0, fb_id;
> + int ret;
> +
> + while (!splash->stop) {
> + /* Are we still in charge? */
> + fb_id = drm_client_display_current_fb(splash->display);
> + if (fb_id != splash->buffer[i]->fb_ids[0])
> + break;
> +
> + /*
> + * We can race with userspace here between checking and doing
> + * the page flip, so double buffering isn't such a good idea.
> + * Tearing probably isn't a problem on a presumably small splash
> + * animation. I've kept it to test the page flip code.
> + */
I think a much cleaner way to solve all this is to tie it into our master
tracking. If there is a master (even if it's not displaying anything),
then none of the in-kernel clients should display anything.
If there is not, then we grab a temporary/weak master reference which
blocks other masters for the time being, but only until we've complete our
drawing operation. Then the in-kernel client drops that weak reference
again. A very simply solution would be to simply hold the device's master
lock (but I'm not sure whether that would result in deadlocks).
That would mean something like
if (!drm_master_try_internal_acquire())
/* someone else is master */
break;
here instead of your fb id check.
> +
> + i = !i;
> + drm_bootsplash_draw(splash->buffer[i], sequence++);
> + if (sequence == 3)
> + sequence = 0;
> +
> + ret = drm_client_display_page_flip(splash->display,
> + splash->buffer[i]->fb_ids[0],
> + true);
> + if (!ret) {
> + event = drm_client_read_event(splash->client, true);
> + if (!IS_ERR(event))
> + kfree(event);
> + }
And
drm_master_interal_relase()
here before we sleep again. Similar for all the fbdev ioctls and all that
stuff.
Just an idea, names definitely need improvements, and I have no idea
wheter it'll work. But using the same logic in the existing fbdev
emulation code would be really good (since that's used a lot more, at
least right now).
-Daniel
> + msleep(500);
> + }
> +
> + for (i = 0; i < 2; i++)
> + drm_client_framebuffer_delete(splash->buffer[i]);
> + drm_client_display_free(splash->display);
> +}
> +
> +static int drm_bootsplash_setup(struct drm_bootsplash *splash)
> +{
> + struct drm_client_dev *client = splash->client;
> + struct drm_client_buffer *buffer[2];
> + struct drm_client_display *display;
> + struct drm_mode_modeinfo *mode;
> + int ret, i;
> +
> + display = drm_client_display_get_first_enabled(client, false);
> + if (IS_ERR(display))
> + return PTR_ERR(display);
> + if (!display)
> + return -ENOENT;
> +
> + mode = drm_client_display_first_mode(display);
> + if (!mode) {
> + ret = -EINVAL;
> + goto err_free_display;
> + }
> +
> + for (i = 0; i < 2; i++) {
> + buffer[i] = drm_client_framebuffer_create(client, mode,
> + DRM_FORMAT_XRGB8888);
> + if (IS_ERR(buffer[i])) {
> + ret = PTR_ERR(buffer[i]);
> + goto err_free_buffer;
> + }
> + }
> +
> + ret = drm_client_display_commit_mode(display, buffer[0]->fb_ids[0], mode);
> + if (ret)
> + goto err_free_buffer;
> +
> + splash->display = display;
> + splash->buffer[0] = buffer[0];
> + splash->buffer[1] = buffer[1];
> +
> + schedule_work(&splash->worker);
> +
> + return 0;
> +
> +err_free_buffer:
> + for (i--; i >= 0; i--)
> + drm_client_framebuffer_delete(buffer[i]);
> +err_free_display:
> + drm_client_display_free(display);
> +
> + return ret;
> +}
> +
> +static int drm_bootsplash_client_hotplug(struct drm_client_dev *client)
> +{
> + struct drm_bootsplash *splash = client->private;
> + int ret = 0;
> +
> + if (!splash->display)
> + ret = drm_bootsplash_setup(splash);
> +
> + return ret;
> +}
> +
> +static int drm_bootsplash_client_new(struct drm_client_dev *client)
> +{
> + struct drm_bootsplash *splash;
> +
> + splash = kzalloc(sizeof(*splash), GFP_KERNEL);
> + if (!splash)
> + return -ENOMEM;
> +
> + INIT_WORK(&splash->worker, drm_bootsplash_worker);
> +
> + splash->client = client;
> + client->private = splash;
> +
> + /*
> + * vc4 isn't done with it's setup when drm_dev_register() is called.
> + * It should have shouldn't it?
> + * So to keep it from crashing defer setup to hotplug...
> + */
> + if (client->dev->mode_config.max_width)
> + drm_bootsplash_client_hotplug(client);
> +
> + return 0;
> +}
> +
> +static int drm_bootsplash_client_remove(struct drm_client_dev *client)
> +{
> + struct drm_bootsplash *splash = client->private;
> +
> + if (splash->display) {
> + splash->stop = true;
> + flush_work(&splash->worker);
> + }
> +
> + kfree(splash);
> +
> + return 0;
> +}
> +
> +static const struct drm_client_funcs drm_bootsplash_client_funcs = {
> + .name = "drm_bootsplash",
> + .new = drm_bootsplash_client_new,
> + .remove = drm_bootsplash_client_remove,
> + .hotplug = drm_bootsplash_client_hotplug,
> +};
> +
> +static int __init drm_bootsplash_init(void)
> +{
> + return drm_client_register(&drm_bootsplash_client_funcs);
> +}
> +module_init(drm_bootsplash_init);
> +
> +static void __exit drm_bootsplash_exit(void)
> +{
> + drm_client_unregister(&drm_bootsplash_client_funcs);
> +}
> +module_exit(drm_bootsplash_exit);
> +
> +MODULE_LICENSE("GPL");
> --
> 2.15.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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