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backend/drm: allow legacy scan-out if FB props match 

Historically we haven't allowed direct scan-out for legacy KMS,
because legacy misses the functionality to make sure a buffer can
be scanned out. However with renderer v6 the backend can't figure
out anymore whether the buffer comes from its internal swap-chain,
because the backend doesn't have an internal swap-chain.

The legacy KMS API guarantees that the driver won't reject a buffer
as long as it's been allocated with the same parameters as the
previous one. Let's check this in legacy_crtc_test.
This commit is contained in:
Simon Ser 2021-07-08 16:52:59 +02:00
parent 6aadf811aa
commit 85d7ad2eef
1 changed files with 41 additions and 4 deletions
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41
backend/drm/legacy.c
View File

@ -8,14 +8,51 @@
#include "backend/drm/iface.h"
#include "backend/drm/util.h"
static bool legacy_fb_props_match(struct wlr_drm_fb *fb1,
struct wlr_drm_fb *fb2) {
if (fb1->wlr_buf->width != fb2->wlr_buf->width ||
fb1->wlr_buf->height != fb2->wlr_buf->height ||
gbm_bo_get_format(fb1->bo) != gbm_bo_get_format(fb2->bo) ||
gbm_bo_get_modifier(fb1->bo) != gbm_bo_get_modifier(fb2->bo) ||
gbm_bo_get_plane_count(fb1->bo) != gbm_bo_get_plane_count(fb2->bo)) {
return false;
}
for (int i = 0; i < gbm_bo_get_plane_count(fb1->bo); i++) {
if (gbm_bo_get_stride_for_plane(fb1->bo, i) !=
gbm_bo_get_stride_for_plane(fb2->bo, i)) {
return false;
}
if (gbm_bo_get_offset(fb1->bo, i) != gbm_bo_get_offset(fb2->bo, i)) {
return false;
}
}
return true;
}
static bool legacy_crtc_test(struct wlr_drm_connector *conn,
const struct wlr_output_state *state) {
struct wlr_drm_crtc *crtc = conn->crtc;
if ((state->committed & WLR_OUTPUT_STATE_BUFFER) &&
state->buffer_type == WLR_OUTPUT_STATE_BUFFER_SCANOUT) {
state->buffer_type == WLR_OUTPUT_STATE_BUFFER_SCANOUT &&
!drm_connector_state_is_modeset(state)) {
struct wlr_drm_fb *pending_fb = crtc->primary->pending_fb;
struct wlr_drm_fb *prev_fb = crtc->primary->queued_fb;
if (!prev_fb) {
prev_fb = crtc->primary->current_fb;
}
/* Legacy is only guaranteed to be able to display a FB if it's been
* allocated the same way as the previous one. */
if (prev_fb != NULL && !legacy_fb_props_match(prev_fb, pending_fb)) {
wlr_drm_conn_log(conn, WLR_DEBUG,
"Cannot use direct scan-out with legacy KMS API");
"Cannot change scan-out buffer parameters with legacy KMS API");
return false;
}
}
return true;
}