On Wed, Jul 26, 2017 at 10:56:32PM +0200, Takashi Iwai wrote:
> Currently the DRM fbcon helper for console blank,
> drm_fb_helper_blank(), simply calls drm_fb_helper_dpms() and always
> returns zero, supposing the driver dealing with DPMS properly for
> blanking the screen. However, it turned out that the console blank
> doesn't work at all on KVM/QEMU when DRM driver is used: most of the
> relevant drivers (bochs, qxl, and virtio) just ignore DPMS, and even
> cirrus driver doesn't work because the DPMS register bits the driver
> fiddles with are also ignored by KVM/QEMU.
>
> A simple fix for this problem would be not to rely on DPMS but let
> fbcon performs the generic blank code. This can be achieved just by
> returning an error from drm_fb_helper_blank().
>
> In this patch, we change the drm_fb_helper_dpms() to give back an
> error code returned from the connector dpms callback, so that the
> error is propagated to drm_fb_helper_blank(). After this change, each
> driver needs just to return an error to fall back to the generic fbcon
> blank mode.
>
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
This needs to be rebased onto -next, this code changed a lot.
-Daniel
> ---
> drivers/gpu/drm/drm_fb_helper.c | 30 ++++++++++++++++++++----------
> 1 file changed, 20 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 574af01d3ce9..db31747ae598 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -581,21 +581,22 @@ static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = {
> static struct sysrq_key_op sysrq_drm_fb_helper_restore_op = { };
> #endif
>
> -static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
> +static int drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
> {
> struct drm_fb_helper *fb_helper = info->par;
> struct drm_device *dev = fb_helper->dev;
> struct drm_crtc *crtc;
> struct drm_connector *connector;
> int i, j;
> + int ret = 0;
>
> /*
> * For each CRTC in this fb, turn the connectors on/off.
> */
> drm_modeset_lock_all(dev);
> if (!drm_fb_helper_is_bound(fb_helper)) {
> - drm_modeset_unlock_all(dev);
> - return;
> + ret = -ENODEV;
> + goto out;
> }
>
> for (i = 0; i < fb_helper->crtc_count; i++) {
> @@ -607,12 +608,16 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
> /* Walk the connectors & encoders on this fb turning them on/off */
> drm_fb_helper_for_each_connector(fb_helper, j) {
> connector = fb_helper->connector_info[j]->connector;
> - connector->funcs->dpms(connector, dpms_mode);
> + ret = connector->funcs->dpms(connector, dpms_mode);
> + if (ret < 0)
> + goto out;
> drm_object_property_set_value(&connector->base,
> dev->mode_config.dpms_property, dpms_mode);
> }
> }
> + out:
> drm_modeset_unlock_all(dev);
> + return ret;
> }
>
> /**
> @@ -622,32 +627,37 @@ static void drm_fb_helper_dpms(struct fb_info *info, int dpms_mode)
> */
> int drm_fb_helper_blank(int blank, struct fb_info *info)
> {
> + int dpms_mode;
> +
> if (oops_in_progress)
> return -EBUSY;
>
> switch (blank) {
> /* Display: On; HSync: On, VSync: On */
> case FB_BLANK_UNBLANK:
> - drm_fb_helper_dpms(info, DRM_MODE_DPMS_ON);
> + dpms_mode = DRM_MODE_DPMS_ON;
> break;
> /* Display: Off; HSync: On, VSync: On */
> case FB_BLANK_NORMAL:
> - drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
> + dpms_mode = DRM_MODE_DPMS_STANDBY;
> break;
> /* Display: Off; HSync: Off, VSync: On */
> case FB_BLANK_HSYNC_SUSPEND:
> - drm_fb_helper_dpms(info, DRM_MODE_DPMS_STANDBY);
> + dpms_mode = DRM_MODE_DPMS_STANDBY;
> break;
> /* Display: Off; HSync: On, VSync: Off */
> case FB_BLANK_VSYNC_SUSPEND:
> - drm_fb_helper_dpms(info, DRM_MODE_DPMS_SUSPEND);
> + dpms_mode = DRM_MODE_DPMS_SUSPEND;
> break;
> /* Display: Off; HSync: Off, VSync: Off */
> case FB_BLANK_POWERDOWN:
> - drm_fb_helper_dpms(info, DRM_MODE_DPMS_OFF);
> + dpms_mode = DRM_MODE_DPMS_OFF;
> break;
> + default:
> + return 0; /* ignored */
> }
> - return 0;
> +
> + return drm_fb_helper_dpms(info, dpms_mode);
> }
> EXPORT_SYMBOL(drm_fb_helper_blank);
>
> --
> 2.13.3
>
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> https://lists.freedesktop.org/mailman/listinfo/dri-devel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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