hi all,
when I run modetest process in libdrm to test our drm module, I find a strange problem:
The test successfully opened /dev/dri/card0 (major:226 minor:0) device by using module name.
but the returned message about crtc, encoder and connector are all empty. I confirm the num of them
is one when our drm device driver register in kernel. So I track the kernel and find here:
drivers/gpu/drm/drm_crtc.c
1806 if (!drm_is_primary_client(file_priv)) {
1807
1808 mode_group = NULL;
1809 list_for_each(lh, &dev->mode_config.crtc_list)
1810 crtc_count++;
1811
1812 list_for_each(lh, &dev->mode_config.connector_list)
1813 connector_count++;
1814
1815 list_for_each(lh, &dev->mode_config.encoder_list)
1816 encoder_count++;
1817 } else {
1818
1819 mode_group = &file_priv->master->minor->mode_group;
1820 crtc_count = mode_group->num_crtcs;
1821 connector_count = mode_group->num_connectors;
1822 encoder_count = mode_group->num_encoders;
1823 }
The device we opened with type of DRM_MINOR_LEGACY, so here come into else branch. The description
of drm_mode_group is that struct drm_mode_group - group of mode setting resources for potential sub-grouping,
and the note in drm_crtc.h also said :
943 * Currently this simply tracks the global mode setting state. But in the
944 * future it could allow groups of objects to be set aside into independent
945 * control groups for use by different user level processes (e.g. two X servers
946 * running simultaneously on different heads, each with their own mode
947 * configuration and freedom of mode setting).
I doubt the empty result has some relations with it, so I continue to track the kernel in function
drm_open, and I find mode_group lies in drm_minor, whick can be found by inode in function drm_open.
But when we create a crtc, encoder or connector, we do nothing to mode_group, just initializing it
when drm_core register. Can you help me and give me some advice?
regards,
Yunlei He
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