From 3845392426e9798c1fb2a6fc5e97bf5dfd5c443d Mon Sep 17 00:00:00 2001 From: Niclas Zeising Date: Tue, 14 Apr 2020 17:01:57 +0200 Subject: [PATCH] Fix return value check of drmIoctl() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When the drmModeSetCursor2() call was replaced with bare drmIoctl() call in 92df7097, a bug was introduced. With the use of drmModeSetCursor2(), the return value from drmIoctl() (which calls ioctl()) were mangled, if they were negative, they were replaced by -errno by a wrapper function in xf86drMode.c in libdrm. After replacing drmModeSetCursor2() with the call to drmIoctl(), this mangling no longer happens, and we need to explicitly check if the call to drmIoctl() fails, which is indicated by returning -1, and then why it failed, by checking errno. If the error indicated by errno is EINVAL, then we can't use the DRM_IOCTL_MODE_CURSOR2 ioctl(), and need to fall back to the DRM_IOCTL_MODE_CURSOR ioctl(). This bug can manifest itself by an invisible hw cursor on systems where the DRM_IOCTL_MODE_CURSOR2 is not implemented by the graphics driver. Credit also to Alexey Dokuchaev for help with developing the fix and testing. This fixes #190 Signed-off-by: Niclas Zeising Reviewed-by: Michel Dänzer --- src/drmmode_display.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/drmmode_display.c b/src/drmmode_display.c index 0e9e2474..72f96a0c 100644 --- a/src/drmmode_display.c +++ b/src/drmmode_display.c @@ -1275,7 +1275,7 @@ drmmode_show_cursor (xf86CrtcPtr crtc) arg.hot_y = yhot; ret = drmIoctl(pRADEONEnt->fd, DRM_IOCTL_MODE_CURSOR2, &arg); - if (ret == -EINVAL) + if (ret == -1 && errno == EINVAL) use_set_cursor2 = FALSE; else return; -- GitLab