int drm_irq_by_busid (struct inode * inode, struct file * filp, unsigned int cmd, unsigned long arg);
\param inode device inode. \param filp file pointer. \param cmd command. \param arg user argument, pointing to a drm_irq_busid structure. \return zero on success or a negative number on failure.
Finds the PCI device with the specified bus id and gets its IRQ number. This IOCTL is deprecated, and will now return EINVAL for any busid not equal to that of the device that this DRM instance attached to.