[PATCH xserver] modesetting: Blacklist EVDI devices from PRIME sync

[Dawid Kurek]

UDL (usb) devices are blacklisted because of they weird behaviour when
it comes to vblank events. As EVDI uses very similar model of handling
vblanks it should be treated similarly.

When doing a page flip, EVDI does not wait for real vblank, but
simulates it by adding constant delay. It also does not support
DRM_IOCTL_WAIT_VBLANK.

In contrast to UDL, EVDI uses platform devices, thus instead of 'usb' in
path they all have 'platform'.

It is possible to blacklist by 'platform', so without explicitly saying
'evdi', but it might be misleading when it comes to real reason for it.

Signed-off-by: Dawid Kurek <dawid.kurek at displaylink.com>
---
 hw/xfree86/drivers/modesetting/driver.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/xfree86/drivers/modesetting/driver.c b/hw/xfree86/drivers/modesetting/driver.c
index f371198..47a1ece 100644
--- a/hw/xfree86/drivers/modesetting/driver.c
+++ b/hw/xfree86/drivers/modesetting/driver.c
@@ -1199,6 +1199,11 @@ msEnableSharedPixmapFlipping(RRCrtcPtr crtc, PixmapPtr front, PixmapPtr back)
          * vblank events */
         if (syspath && strstr(syspath, "usb"))
             return FALSE;
+
+        /* EVDI uses USB transport but is platform device, not usb.
+         * Blacklist it explicitly */
+        if (syspath && strstr(syspath, "evdi"))
+            return FALSE;
     }
 #endif
 
-- 
2.7.4