int drm_infobufs (struct inode * inode, struct file * filp, unsigned int cmd, unsigned long arg);
This was originally mean for debugging purposes, or by a sophisticated client library to determine how best to use the available buffers (e.g., large buffers can be used for image transfer).
\param inode device inode. \param filp file pointer. \param cmd command. \param arg pointer to a drm_buf_info structure. \return zero on success or a negative number on failure.
:buf_use while holding the drm_device::count_lock lock, preventing of allocating more buffers after this call. Information about each requested buffer is then copied into user space.