On Sun, 19 Nov 2023 18:35:27 +0100, Geoffrey D. Bennett wrote: > > Hi Jaroslav, Takashi, > > I took your feedback onboard about not providing generic access to the > scarlett2_usb() function from user-space. > > After a few iterations, I've come up with this hwdep interface to > support reset-to-factory-defaults, reset-to-factory-firmware, and > firmware-update in a safe way: > > -----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<----- > > /* Get protocol version */ > #define SCARLETT2_IOCTL_PVERSION _IOR('S', 0x60, int) > > /* Reboot */ > #define SCARLETT2_IOCTL_REBOOT _IO('S', 0x61) > > /* Select flash segment */ > #define SCARLETT2_SEGMENT_ID_SETTINGS 0 > #define SCARLETT2_SEGMENT_ID_FIRMWARE 1 > #define SCARLETT2_SEGMENT_ID_COUNT 2 > > #define SCARLETT2_IOCTL_SELECT_FLASH_SEGMENT _IOW('S', 0x62, int) > > /* Erase selected flash segment */ > #define SCARLETT2_IOCTL_ERASE_FLASH_SEGMENT _IO('S', 0x63) > > /* Get selected flash segment erase progress > * 1 through to num_blocks, or 255 for complete > */ > struct scarlett2_flash_segment_erase_progress { > unsigned char progress; > unsigned char num_blocks; > }; > #define SCARLETT2_IOCTL_GET_ERASE_PROGRESS \ > _IOR('S', 0x64, struct scarlett2_flash_segment_erase_progress) > > -----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<-----8<----- > > Does that look reasonable to you? > > Broadly, it's used like this: > > Reset to factory default configuration: > > - ioctl select_flash_segment SCARLETT2_SEGMENT_ID_SETTINGS > - ioctl erase_flash_segment > - ioctl get_erase_progress (optional) So the erase operation is asynchronous? This sounds a bit dangerous. Will the driver block further conflicting operations until the erase finishes? > Erase firmware (reverts to factory firmware which is stored in a > different flash segment, inaccessible from these ioctls): > > - ioctl select_flash_segment SCARLETT2_SEGMENT_ID_FIRMWARE > - ioctl erase_flash_segment > - ioctl get_erase_progress (optional) > > Upload new firmware: > > - write() <- a bunch of these, only permitted after the previous erase > step was completed The write op must accept partial writes, and it becomes cumbersome. Can it be a one-shot ioctl, too? > On completion: > > - ioctl reboot > > To confirm that this interface is sufficient, I have implemented it in > the scarlett2 driver and written a user-space utility which can > perform all the above operations. > > I will clean up the implementation a bit and then submit for review; > just wanted to share the interface first in case you have any comments > at this point. IMO, from the user POV, it's easier to have per-purpose ioctls, instead of combining multiple ioctl sequences. Of course, it won't scale too much, but for the limited number of operations, it's clearer. That is, we can provide just a few ioctls for reset-to-factory, reset-to-something-else, and update. But, if you need asynchronous operations inevitably by some reason, it's a different story, though. thanks, Takashi