On Wed, Sep 23, 2026 at 09:48:58AM -0600, Mathieu Poirier wrote:
> On Tue, Sep 22, 2026 at 10:19:48PM +0200, Francesco Valla wrote:
> > On Tue, Sep 22, 2026 at 09:43:52AM -0600, Mathieu Poirier wrote:
> > > On Wed, Sep 16, 2026 at 11:10:57PM +0200, Francesco Valla wrote:
> > > > Add rings for multiple vdevs, as well as the required virtio nodes for
> > > > I2C, SPI and GPIO functionalities. On top of that, add example
> > > > peripherals using all of them.
> > > >
> > > > NOTE: this is a Proof-Of-Concept, not meant to be integrated!
> > > >
> > > > Signed-off-by: Francesco Valla <[email protected]>
> > > > ---
> > > > arch/arm64/boot/dts/freescale/imx93-11x11-frdm.dts | 128
> > > > +++++++++++++++++++--
> > > > 1 file changed, 119 insertions(+), 9 deletions(-)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/freescale/imx93-11x11-frdm.dts
> > > > b/arch/arm64/boot/dts/freescale/imx93-11x11-frdm.dts
> > > > index bd14ba28690c..dfa3b122ac5f 100644
> > > > --- a/arch/arm64/boot/dts/freescale/imx93-11x11-frdm.dts
> > > > +++ b/arch/arm64/boot/dts/freescale/imx93-11x11-frdm.dts
> > > > @@ -53,6 +53,32 @@ button-k3 {
> > > > };
> > > > };
> > > >
> > > > + gpio-keys-virtio {
> > > > + compatible = "gpio-keys-polled";
> > > > + poll-interval = <100>;
> > > > +
> > > > + button-v1 {
> > > > + label = "Button V1";
> > > > + linux,code = <BTN_3>;
> > > > + gpios = <&v_gpio 23 GPIO_ACTIVE_LOW>;
> > > > + };
> > > > +
> > > > + button-v2 {
> > > > + label = "Button V2";
> > > > + linux,code = <BTN_4>;
> > > > + gpios = <&v_gpio 24 GPIO_ACTIVE_LOW>;
> > > > + };
> > > > + };
> > > > +
> > > > + leds {
> > > > + compatible = "gpio-leds";
> > > > +
> > > > + led {
> > > > + gpios = <&v_gpio 18 GPIO_ACTIVE_HIGH>;
> > > > + label = "LED V";
> > > > + };
> > > > + };
> > > > +
> > > > reg_usdhc2_vmmc: regulator-usdhc2 {
> > > > compatible = "regulator-fixed";
> > > > off-on-delay-us = <12000>;
> > > > @@ -89,11 +115,6 @@ linux,cma {
> > > > linux,cma-default;
> > > > };
> > > >
> > > > - rsc_table: rsc-table@2021e000 {
> > > > - reg = <0 0x2021e000 0 0x1000>;
> > > > - no-map;
> > > > - };
> > > > -
> > >
> > > Why is the resource table removed? There is no mention of that in the
> > > changelog...
> > >
> >
> > You are obviously right, the commit message here should have been a
> > poem, not a form of hermetic poetry. My bad.
> >
> > The resource table here is causing problems with how Zephyr is managing
> > it at its side. If it is kept in a separate memory location and copied
> > there at runtime by the remote processor firmware during its startup
> > (which is the current Zephyr behavior), then there might be a race
> > condition when the aforesaid firmware is loaded and started by Linux
> > *and* at least one of the vdev drivers (here including rpmsg_bus) is
> > built-in. In this case, the copy of the resource table done by the
> > remote processor might - depending on the async execution of the two
> > processors - overwrite the status bit set by the Linux driver:
> >
> > Firmware load and startup (echo start > /sys/.../state)
> > |
> > |
> > V
> > The vdev devices get registered (by register_virtio_device())
> > |
> > |
> > V
> > If a driver is built-in, it probes and sets the vdev status
> > inside the resource table @rsc-table.
> > .
> > . (in the mean time)
> > .
> > The remote processor starts up and copies the resource table from its
> > dedicated section to @rsc-table.
> >
> > Depending on the system load and the complexity of the firmware, the two
> > operations can happen in whatever sequence, causing a race condition.
>
> This would happen regardless of this patchset.
>
Correct, *if* the remote processor is copying the resource table to a
specific location and expects the host to use that. On Zephyr (which is
clearly outside the scope here) this can be enabled through the
CONFIG_OPENAMP_COPY_RSC_TABLE option. I am keeping that disabled, and
removing the rsc-table node here.
I am planning to reason on this and propose a proper fix in a separate
patchset.
> >
> > This is somewhat masked if vdev drivers are built as modules, as the
> > devices does not probe immediately but only after the modules have been
> > loaded, giving the remote processor time to start. Note that this is not
> > a solution! but a workaround.
> >
> > If the rsc-table node is not there, the startup logic falls back to the
> > classic rproc_elf_find_loaded_rsc_table().
>
> We can't remove @rsc-table to make a problem go away.
>
I need to re-take a look at the NXP SDK to understand what's the real
purpose of having the rsc-table here. Judging from the commit message
that introduced support for such facility [1], it seems the SDK is not
really using it.
Maybe someone from NXP can comment on this?
> >
> > This is specific to i.MX platforms [1] and is probably not normally an
> > issue because - as stated in [1] - the offical SDK from NXP seems not
> > to check the status inside the resource table.
> >
> > > > vdev0vring0: vdev0vring0@a4000000 {
> > > > reg = <0 0xa4000000 0 0x8000>;
> > > > no-map;
> > > > @@ -105,12 +126,42 @@ vdev0vring1: vdev0vring1@a4008000 {
> > > > };
> > > >
> > > > vdev1vring0: vdev1vring0@a4010000 {
> > > > - reg = <0 0xa4010000 0 0x8000>;
> > > > + reg = <0 0xa4010000 0 0x1000>;
> > > > + no-map;
> > > > + };
> > > > +
> > > > + vdev2vring0: vdev2vring0@a4011000 {
> > > > + reg = <0 0xa4011000 0 0x2000>;
> > > > + no-map;
> > > > + };
> > > > +
> > > > + vdev2vring1: vdev2vring1@a4013000 {
> > > > + reg = <0 0xa4013000 0 0x2000>;
> > > > + no-map;
> > > > + };
> > > > +
> > > > + vdev3vring0: vdev3vring0@a4015000 {
> > > > + reg = <0 0xa4015000 0 0x2000>;
> > > > + no-map;
> > > > + };
> > > > +
> > > > + vdev4vring0: vdev4vring0@a4017000 {
> > > > + reg = <0 0xa4017000 0 0x4000>;
> > > > + no-map;
> > > > + };
> > > > +
> > > > + vdev5vring0: vdev5vring0@a401B000 {
> > > > + reg = <0 0xa401B000 0 0x2000>;
> > > > + no-map;
> > > > + };
> > > > +
> > > > + vdev5vring1: vdev5vring1@a401D000 {
> > > > + reg = <0 0xa401D000 0 0x2000>;
> > > > no-map;
> > > > };
> > > >
> > > > - vdev1vring1: vdev1vring1@a4018000 {
> > > > - reg = <0 0xa4018000 0 0x8000>;
> > > > + vdev5vring2: vdev5vring2@a401F000 {
> > > > + reg = <0 0xa401F000 0 0x1000>;
> > > > no-map;
> > > > };
> > > >
> > > > @@ -149,8 +200,67 @@ &cm33 {
> > > > <&mu1 3 1>;
> > > > mbox-names = "tx", "rx", "rxdb";
> > > > memory-region = <&vdevbuffer>, <&vdev0vring0>, <&vdev0vring1>,
> > > > - <&vdev1vring0>, <&vdev1vring1>, <&rsc_table>;
> > > > + <&vdev1vring0>, <&vdev2vring0>, <&vdev2vring1>,
> > > > + <&vdev3vring0>, <&vdev4vring0>,
> > > > + <&vdev5vring0>, <&vdev5vring1>, <&vdev5vring2>;
> > >
> > > Who is using vdev5 vrings?
> > >
> >
> > Another thing that should have been in the commit message. Vdevs are
> > defined, in the Zephyr application I am using as PoC, as follows:
> >
> > - vdev0: RPMSG (tx and rx vrings)
>
> To be backward compatible, there has to be a way to make vdev0 defaulting to
> RPMSG. It would also be nice if bindings were define for RPMSG so that it can
> show up in the list of remoteproc-virtio devices like i2c, gpio and others.
>
What vdev type is inside vdev0 is up to the resource table (i.e., to the
firmware running on the remote processor), not the remoteproc-virtio
framework.
Defining bindings for rpmsg would today be... pointless? Since no
hardware needs to be described for it. The same goes for virtio-can and
virtio-entropy.
>
> > - vdev1: entropy (single request vring)
> > - vdev2: GPIO (request and event vrings)
> > - vdev3: I2C (single request vring)
> > - vdev4: SPI (single request vring)
> > - vdev5: CAN (tx, rx and control vrings)
> >
> > vdev5 is not represented inside the devicetree because the can-virtio
> > driver registers a single CAN network device and has thus no need for
> > such representation.
>
> Then why is it part of the remoteproc's memory-regions?
>
Because a vring description needs to be present for it, or the
remoteproc-virtio won't be able to fill the entry inside the resource
table.
> >
> > > > status = "okay";
> > > > +
> > > > + virtio {
> > > > + #address-cells = <1>;
> > > > + #size-cells = <0>;
> > > > +
> > > > + vdev@2 {
> > > > + reg = <2>;
> > > > +
> > > > + v_gpio: gpio {
> > > > + compatible = "virtio,device29";
> > > > + gpio-controller;
> > > > + #gpio-cells = <2>;
> > > > + interrupt-controller;
> > > > + #interrupt-cells = <2>;
> > > > + };
> > > > + };
> > > > +
> > > > + vdev@3 {
> > > > + reg = <3>;
> > > > +
> > > > + i2c {
> > > > + compatible = "virtio,device22";
> > > > + #address-cells = <1>;
> > > > + #size-cells = <0>;
> > > > +
> > > > + eeprom@50 {
> > > > + compatible = "atmel,24c1025";
> > > > + reg = <0x50>;
> > > > + };
> > > > + };
> > > > + };
> > > > +
> > > > + vdev@4 {
> > > > + reg = <4>;
> > > > +
> > > > + spi {
> > > > + compatible = "virtio,device2d";
> > > > + #address-cells = <1>;
> > > > + #size-cells = <0>;
> > > > +
> > > > + sram@0 {
> > > > + compatible =
> > > > "microchip,mchp23k256";
> > > > + reg = <0>;
> > > > + spi-max-frequency = <20000000>;
> > > > + };
> > > > +
> > > > + lcd@1 {
> > > > + compatible =
> > > > "adafruit,yx240qv29", "ilitek,ili9341";
> > > > + reg = <1>;
> > > > + spi-max-frequency = <10000000>;
> > > > + dc-gpios = <&v_gpio 21
> > > > GPIO_ACTIVE_HIGH>;
> > > > + reset-gpios = <&v_gpio 20
> > > > GPIO_ACTIVE_HIGH>;
> > > > + rotation = <90>;
> > > > + };
> > > > + };
> > > > + };
> > > > + };
> > > > };
> > > >
> > > > &eqos {
> > > >
> > > > --
> > > > 2.55.0
> > > >
> >
> > Thank you!
> >
> > Regards,
> > Francesco
> >
> >
Thank you for the discussion - is helping in defining further
requirements and constraints.
Regards,
Francesco
[1] https://lore.kernel.org/all/[email protected]/
