Messages in this thread Patch in this message | | | Date | Sun, 29 Jan 2006 10:18:19 +0800 | From | "Antonino A. Daplas" <> | Subject | [PATCH] fbdev: Fix usage of blank value passed to fb_blank |
| |
The fb_blank() hook accepts 5 blanking levels which include 1 level designed for console use only. Userspace is only aware of 4 levels. Thus, it's possible for userspace to request VESA_VSYNC_SUSPEND which, in turn, is interpreted by the fb driver as a request for FB_BLANK_NORMAL. A few drivers return -EINVAL for this, confusing userspace apps that the driver may not have VESA blanking support.
Fix by incrementing the blank value by one if the request originated from userspace.
Signed-off-by: Antonino Daplas <adaplas@pol.net> ---
Ingo Oeser wrote: > > May I suggest to hide this implementation detail? > >
Yes. The change will be invisible to drivers.
Unfortunately, this may cause some userland breakage. X should work. However, some apps may have been developed that uses the FB_BLANK constants (DirectFB?). In these cases, they'll get a deeper blank level instead, so it probably won't affect them significantly. A follow up patch that hides the FB_BLANK constants may be worthwhile.
drivers/video/fbmem.c | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c index d2dede6..5bed0fb 100644 --- a/drivers/video/fbmem.c +++ b/drivers/video/fbmem.c @@ -843,6 +843,19 @@ fb_blank(struct fb_info *info, int blank { int ret = -EINVAL; + /* + * The framebuffer core supports 5 blanking levels (FB_BLANK), whereas + * VESA defined only 4. The extra level, FB_BLANK_NORMAL, is a + * console invention and is not related to power management. + * Unfortunately, fb_blank callers, especially X, pass VESA constants + * leading to undefined behavior. + * + * To avoid confusion, fb_blank will assume VESA constants if coming + * from userspace, and FB_BLANK constants if coming from the kernel. + */ + if (info->flags & FBINFO_MISC_USEREVENT && blank) + blank++; + if (blank > FB_BLANK_POWERDOWN) blank = FB_BLANK_POWERDOWN; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |