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drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC

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Implement legacy framebuffer ioctl FBIO_WAITFORVSYNC in the generic
framebuffer emulation driver. Legacy framebuffer users like non kms/drm
based OpenGL(ES)/EGL implementations may require the ioctl to
synchronize drawing or buffer flip for double buffering. It is tested on
the i.MX6.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Maxime Ripard
2017-02-28 16:36:51 +01:00
committed by Daniel Vetter
parent 35f5022fbe
commit 0f3bbe074d
2 changed files with 79 additions and 1 deletions
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68
drivers/gpu/drm/drm_fb_helper.c
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@@ -1244,6 +1244,74 @@ int drm_fb_helper_setcmap(struct fb_cmap *cmap, struct fb_info *info)
}
EXPORT_SYMBOL(drm_fb_helper_setcmap);
/**
* drm_fb_helper_ioctl - legacy ioctl implementation
* @info: fbdev registered by the helper
* @cmd: ioctl command
* @arg: ioctl argument
*
* A helper to implement the standard fbdev ioctl. Only
* FBIO_WAITFORVSYNC is implemented for now.
*/
int drm_fb_helper_ioctl(struct fb_info *info, unsigned int cmd,
unsigned long arg)
{
struct drm_fb_helper *fb_helper = info->par;
struct drm_device *dev = fb_helper->dev;
struct drm_mode_set *mode_set;
struct drm_crtc *crtc;
int ret = 0;
mutex_lock(&dev->mode_config.mutex);
if (!drm_fb_helper_is_bound(fb_helper)) {
ret = -EBUSY;
goto unlock;
}
switch (cmd) {
case FBIO_WAITFORVSYNC:
/*
* Only consider the first CRTC.
*
* This ioctl is supposed to take the CRTC number as
* an argument, but in fbdev times, what that number
* was supposed to be was quite unclear, different
* drivers were passing that argument differently
* (some by reference, some by value), and most of the
* userspace applications were just hardcoding 0 as an
* argument.
*
* The first CRTC should be the integrated panel on
* most drivers, so this is the best choice we can
* make. If we're not smart enough here, one should
* just consider switch the userspace to KMS.
*/
mode_set = &fb_helper->crtc_info[0].mode_set;
crtc = mode_set->crtc;
/*
* Only wait for a vblank event if the CRTC is
* enabled, otherwise just don't do anythintg,
* not even report an error.
*/
ret = drm_crtc_vblank_get(crtc);
if (!ret) {
drm_crtc_wait_one_vblank(crtc);
drm_crtc_vblank_put(crtc);
}
ret = 0;
goto unlock;
default:
ret = -ENOTTY;
}
unlock:
mutex_unlock(&dev->mode_config.mutex);
return ret;
}
EXPORT_SYMBOL(drm_fb_helper_ioctl);
/**
* drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
* @var: screeninfo to check