On 01-03-21, 16:19, Arnd Bergmann wrote: > On Mon, Mar 1, 2021 at 7:41 AM Jie Deng <jie.deng@xxxxxxxxx> wrote: > > > --- /dev/null > > +++ b/include/uapi/linux/virtio_i2c.h > > @@ -0,0 +1,56 @@ > > +/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note */ > > +/* > > + * Definitions for virtio I2C Adpter > > + * > > + * Copyright (c) 2021 Intel Corporation. All rights reserved. > > + */ > > + > > +#ifndef _UAPI_LINUX_VIRTIO_I2C_H > > +#define _UAPI_LINUX_VIRTIO_I2C_H > > Why is this a uapi header? Can't this all be moved into the driver > itself? > > > +/** > > + * struct virtio_i2c_req - the virtio I2C request structure > > + * @out_hdr: the OUT header of the virtio I2C message > > + * @write_buf: contains one I2C segment being written to the device > > + * @read_buf: contains one I2C segment being read from the device > > + * @in_hdr: the IN header of the virtio I2C message > > + */ > > +struct virtio_i2c_req { > > + struct virtio_i2c_out_hdr out_hdr; > > + u8 *write_buf; > > + u8 *read_buf; > > + struct virtio_i2c_in_hdr in_hdr; > > +}; > > In particular, this structure looks like it is only ever usable between > the transfer functions in the driver itself, it is shared with neither > user space nor the virtio host side. Why is it so ? Won't you expect hypervisors or userspace apps to use these ? -- viresh