On Mon, 22 Jun 2015, Josh Boyer jwboyer@fedoraproject.org wrote:
On Mon, Jun 22, 2015 at 9:27 AM, Jani Nikula jani.nikula@linux.intel.com wrote:
On Mon, 22 Jun 2015, Josh Boyer jwboyer@fedoraproject.org wrote:
On Mon, Jun 22, 2015 at 8:02 AM, Daniel Vetter daniel.vetter@ffwll.ch wrote:
We should never nest these since in theory kms drivers should know when a pipe is on/off and call the corresponding enable/disable functions for the vblank helper code only once. But for historical reasons (the shared-with-ums version of this code in modeset_pre/post needed to be able to cope with silly userspace that lost track of things) we still have this bit of "robustness" around.
Enforce this with a WARN_ON, preparing to eventually rip out this special handling.
This doesn't really provide any context in the WARN_ON itself. It will just result in a splat that looks like a kernel oops, and end users and distribution maintainers will be left scratching their heads.
Could this be done with a printk warning instead, or could you at least provide a pr_warn statement to help people understand why their machine has an oops splat?
FWIW i915_drv.h has
#define WARN_ON(x) WARN((x), "WARN_ON(" #x ")")
which makes it a little better...
Only a little though, and only in i915. This is in the generic DRM code, isn't it?
You're absolutely right, sorry. Agreed with your complaint.
BR, Jani.