[PATCH] modesetting: Update fb_id from shadow allocate and destroy if not set

[Tony Lindgren]

Looks like drmModeDirtyFB() stopped working at some point and we now
call it with fb_id of zero for rotated displays. This will stop displays
relying on DRM_IOCTL_MODE_DIRTYFB ioctl to display anything.

This regression probably with commit 3dcd591fa9b7 ("modesetting: Add
support for using RandR shadow buffers") that inroduced rotate_fb_id.

Let's fix this issue by copying rotate_fb_id to fb_id if zero and then
reset it back to zero after we're done with the rotation.

After the fix we then call drmModeDirtyFB() we then have the
following fb_id changes:

$ startx
drmmode_get_default_bpp: fb_id: 51
drmmode_get_default_bpp: cleared fb_id
dispatch_dirty: ms->drmmode.fb_id: 0 fb_id: 0
drmmode_set_mode_major: drmmode->fb_id: 52
dispatch_dirty: ms->drmmode.fb_id: 52 fb_id: 52
...

$ xrandr --output DSI-1 --rotate right
drmmode_xf86crtc_resize: cleared old_fb_id
dispatch_dirty: ms->drmmode.fb_id: 0 fb_id: 0
drmmode_shadow_allocate: drmmode_crtc->rotate_fb_id: 50
dispatch_dirty: ms->drmmode.fb_id: 50 fb_id: 50
...

$ xrandr --output DSI-1 --rotate normal
drmmode_shadow_destroy: cleared drmmode_crtc->rotate_fb_id
dispatch_dirty: ms->drmmode.fb_id: 0 fb_id: 0
dispatch_dirty: ms->drmmode.fb_id: 0 fb_id: 0
dispatch_dirty: ms->drmmode.fb_id: 0 fb_id: 0
drmmode_set_mode_major: drmmode->fb_id: 51
dispatch_dirty: ms->drmmode.fb_id: 51 fb_id: 51
...

Cc: Hans De Goede <hdegoede at redhat.com>
Cc: Jason Ekstrand <jason.ekstrand at intel.com>
Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Cc: Sebastian Reichel <sebastian.reichel at collabora.co.uk>
Cc: Tomi Valkeinen <tomi.valkeinen at ti.com>
Signed-off-by: Tony Lindgren <tony at atomide.com>
---
 hw/xfree86/drivers/modesetting/drmmode_display.c | 10 ++++++++++
 hw/xfree86/drivers/modesetting/drmmode_display.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -997,6 +997,12 @@ drmmode_shadow_allocate(xf86CrtcPtr crtc, int width, int height)
         return NULL;
     }
 
+    /* Must have proper drmmode->fb_id for drmModeDirtyFB() */
+    if (!drmmode->fb_id) {
+        drmmode->fb_id = drmmode_crtc->rotate_fb_id;
+        drmmode_crtc->reset_fb_id = TRUE;
+    }
+
 #ifdef GLAMOR_HAS_GBM
     if (drmmode->gbm)
         return drmmode_crtc->rotate_bo.gbm;
@@ -1084,6 +1090,10 @@ drmmode_shadow_destroy(xf86CrtcPtr crtc, PixmapPtr rotate_pixmap, void *data)
 
     if (data) {
         drmModeRmFB(drmmode->fd, drmmode_crtc->rotate_fb_id);
+        if (drmmode_crtc->reset_fb_id &&
+            drmmode->fb_id == drmmode_crtc->rotate_fb_id)
+            drmmode->fb_id = 0;
+        drmmode_crtc->reset_fb_id = FALSE;
         drmmode_crtc->rotate_fb_id = 0;
 
         drmmode_bo_destroy(drmmode, &drmmode_crtc->rotate_bo);
diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.h b/hw/xfree86/drivers/modesetting/drmmode_display.h
--- a/hw/xfree86/drivers/modesetting/drmmode_display.h
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.h
@@ -98,6 +98,7 @@ typedef struct {
 
     drmmode_bo rotate_bo;
     unsigned rotate_fb_id;
+    Bool reset_fb_id;
 
     PixmapPtr prime_pixmap;
     PixmapPtr prime_pixmap_back;
-- 
2.16.1