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R. Silva" , Marek Szyprowski , Robin Murphy , Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Frank Li , Peng Fan , Sascha Hauer , linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, virtualization@lists.linux.dev, imx@lists.linux.dev, iommu@lists.linux.dev, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH RFC 12/12] PoC: arm64: dts: imx93-11x11-frdm: add multiple vdevs Message-ID: References: <20260916-remoteproc_virtio_map-v1-0-dac8c5eb4aa9@valla.it> <20260916-remoteproc_virtio_map-v1-12-dac8c5eb4aa9@valla.it> Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 > > > --- > > > 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 = ; > > > + gpios = <&v_gpio 23 GPIO_ACTIVE_LOW>; > > > + }; > > > + > > > + button-v2 { > > > + label = "Button V2"; > > > + linux,code = ; > > > + 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. > > 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. > > 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. > - 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? > > > > 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 > > > [1] https://lore.kernel.org/all/20240719-imx_rproc-v2-2-10d0268c7eb1@nxp.com/