> -----Original Message-----
> From: Andrew Lunn <[email protected]>
> Sent: Monday, April 27, 2026 3:49 PM
> To: Shenwei Wang <[email protected]>
> Cc: Padhi, Beleswar <[email protected]>; Linus Walleij <[email protected]>;
> Bartosz Golaszewski <[email protected]>; Jonathan Corbet <[email protected]>;
> Rob Herring <[email protected]>; Krzysztof Kozlowski <[email protected]>;
> Conor Dooley <[email protected]>; Bjorn Andersson
> <[email protected]>; Mathieu Poirier <[email protected]>; Frank Li
> <[email protected]>; Sascha Hauer <[email protected]>; Shuah Khan
> <[email protected]>; [email protected]; linux-
> [email protected]; [email protected]; Pengutronix Kernel Team
> <[email protected]>; Fabio Estevam <[email protected]>; Peng Fan
> <[email protected]>; [email protected]; linux-
> [email protected]; [email protected]; linux-arm-
> [email protected]; dl-linux-imx <[email protected]>; Bartosz
> Golaszewski <[email protected]>
> Subject: [EXT] Re: [PATCH v13 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
> > > struct virtio_gpio_response {
> > > __u8 status;
> > > __u8 value;
> > > };
>
> > It is the same message format. Please see the message definition
> (GET_DIRECTION) below:
>
> > + +-----+-----+-----+-----+-----+----+
> > + |0x00 |0x01 |0x02 |0x03 |0x04 |0x05|
> > + | 1 | 2 |port |line | err | dir|
> > + +-----+-----+-----+-----+-----+----+
>
> Sorry, but i don't see how two u8 vs six u8 are the same message format.
>
Some changes to the message format are necessary.
Virtio uses two communication channels (virtqueues): one for requests and
replies, and a second one for events.
In contrast, rpmsg provides only a single communication channel, so a type
field is required to distinguish between
different kinds of messages.
Since rpmsg replies and events share the same message format, an additional
line is introduced to handle both cases.
Finally, rpmsg supports multiple GPIO controllers, so a port field is added to
uniquely identify the target controller.
Shenwei
> Andrew
