On Thu, Mar 14, 2019 at 04:17:13PM +0530, Jay Aurabind wrote:
On Wed, 13 Mar 2019 at 19:55, Greg KH <greg@kroah.com> wrote:
On Wed, Mar 13, 2019 at 12:02:02PM +0530, Jay Aurabind wrote:
Hi,
Before I send this patch to actual mailing list, I'd appreciate if someone could tell me if this is a bad idea!
The driver in staging for pi433 (a wireless transceiver) uses IOCTLs at the moment. I wish to add a sysfs interface to it that control the various transmission and reception parameters. In the ioctl interface, it uses two structs that have about 40 parameters in total.
For the corresponding sysfs interface, since there are a lot of parameters, would it be justified to use the same binary format though sysfs_create_binary_file() ? The rationale is that it would be easier to simply pack all the config options in the struct and send it in once rather than individually write 40 files. This is what the attached patch follows. Interface is added only for reception parameters as of now.
binary sysfs files are only allowed for "pass through" data, where the kernel does not touch the information at all and only passes it from the hardware, to userspace directly (or the other way around). It can not be used for data that the kernel actually knows about and modifies / acts on.
An example of valid binary sysfs files are USB and PCI device configuration information (read directly from the hardware), or firmware files that are send from userspace directly to the hardware without the kernel knowing what the data is.
You can't use a binary sysfs file for ioctl-like data, that's not allowed, just use an ioctl for that. Or better yet, use a common api interface for it, to match the other types of devices.
Thank you for the explanation. What API would the most appropriate for such a wireless transceiver ? If I could make it as a networking driver, I could probably use setsockopt to pass in these configuration. Is this recommended ?
No, try looking at how v4l2 works, odds are they already have the correct api for this type of device there for you to use. thanks, greg k-h