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b=erovEHfrwiVjs6db7clhZWgHKr 6ePKwQ5dNEKEz+MrT3+BX+d9uRHYQeHDbvnh84YIbungUgI12aH/r75TNn8sfZxC6iKflYy6xeJxK qrk9CvDXRJly/xVYVJEVnYVRODo+kZrA51xsWwKUh+SNeNJq1CbMrlVONb8OsHIFp8v8=; Received: from [79.45.60.29] (port=60504 helo=bywater) by esm19.siteground.biz with essmtpa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.100.1) (envelope-from ) id 1x9RvF-00000000Eam-2iOy; Wed, 23 Sep 2026 18:42:25 +0000 Date: Wed, 23 Sep 2026 20:42:23 +0200 From: Francesco Valla To: Mathieu Poirier Cc: Bjorn Andersson , Kees Cook , "Gustavo A. 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: X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - esm19.siteground.biz X-AntiAbuse: Original Domain - lists.linux.dev X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - valla.it X-Source: X-Source-Args: X-Source-Dir: X-SGantispam-id: 442b37c6f320d51931536ce9c167821c X-AntiAbuse: ID - 442b37c6f320d51931536ce9c167821c AntiSpam-DLS: false AntiSpam-DLSP: AntiSpam-DLSRS: AntiSpam-TS: 1.0 CFBL-Address: feedback@antispam.mailspamprotection.com; report=arf CFBL-Feedback-ID: 1x9Rvb-000000065gT-3FnM-feedback@antispam.mailspamprotection.com Authentication-Results: outgoing.instance-europe-west4-fjbh.prod.antispam.mailspamprotection.com; iprev=pass (214.173.214.35.bc.googleusercontent.com) smtp.remote-ip=35.214.173.214; auth=pass (LOGIN) smtp.auth=esm19.siteground.biz; dkim=pass header.d=valla.it header.s=default header.a=rsa-sha256; arc=none 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 > > > > --- > > > > 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. > 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/20240719-imx_rproc-v2-2-10d0268c7eb1@nxp.com/