Hi Dan, > > + struct goldfish_audio *audio = fp->private_data; > > I've never written a misc driver (or any substantial kernel code at all > if I'm being honest. :P) but I think fp->private_data is a pointer to > &goldfish_audio_device. > > But then that wouldn't ever work, and how was this tested then??? I followed other parts in this driver: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/tree/drivers/staging/goldfish/goldfish_audio.c?h=v4.17.6#n118 static ssize_t goldfish_audio_read(struct file *fp, char __user *buf, size_t count, loff_t *pos) { struct goldfish_audio *data = fp->private_data; I assumed it points where we want, otherwise yes, we would notice this. I checked other drivers and they do use private_data for similar purposes. The thing I missed is they set private_data in open, e.g.: struct scr24x_dev *dev = container_of(inode->i_cdev, struct scr24x_dev, c_dev); filp->private_data = dev; Unfortunately, I cannot figure out how to pass a pointer from probe to open. probe in examples (scr24x_cs.c) calls cdev_init which I am not sure if applicable here. _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
