On Wed, 29 Apr 2026 at 10:53, Shenwei Wang <[email protected]> wrote: > > > > > -----Original Message----- > > From: Mathieu Poirier <[email protected]> > > Sent: Wednesday, April 29, 2026 10:42 AM > > To: Shenwei Wang <[email protected]> > > Cc: Andrew Lunn <[email protected]>; 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]>; Frank Li <[email protected]>; Sascha Hauer > > <[email protected]>; Shuah Khan <[email protected]>; linux- > > [email protected]; [email protected]; > > [email protected]; > > Pengutronix Kernel Team <[email protected]>; Fabio Estevam > > <[email protected]>; Peng Fan <[email protected]>; > > [email protected]; [email protected]; > > [email protected]; [email protected]; dl-linux-imx > > <linux- > > [email protected]>; Bartosz Golaszewski <[email protected]> > > Subject: [EXT] Re: [PATCH v13 3/4] gpio: rpmsg: add generic rpmsg GPIO > > driver > > On Tue, Apr 28, 2026 at 03:24:59PM +0000, Shenwei Wang wrote: > > > > > > > > > > -----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. > > > > I have commented on this before - RPMSG is already providing multiplexing > > capability by way of endpoints. There is no need for a port field. One > > endpoint, > > one GPIO controller. > > > > You still need a way to let the remote side know which port the endpoint maps > to, either > by embedding the port information in the message (the current way), or by > sending it > separately. >
An endpoint is created with every namespace request. There should be one namespace request for every GPIO controller, which yields a unique endpoint for each controller and eliminates the need for an extra field to identify them. > Shenwei > > > > > > > Shenwei > > > > > > > Andrew
