On 28/07/25 6:10 pm, Krzysztof Kozlowski wrote: > On 28/07/2025 10:10, MD Danish Anwar wrote: >> Hi Krzysztof, >> >> On 25/07/25 12:48 am, Krzysztof Kozlowski wrote: >>> On 23/07/2025 10:03, MD Danish Anwar wrote: >>>> This patch introduces a basic RPMSG Ethernet driver skeleton. It adds >>> >>> Please do not use "This commit/patch/change", but imperative mood. See >>> longer explanation here: >>> https://elixir.bootlin.com/linux/v5.17.1/source/Documentation/process/submitting-patches.rst#L95 >>> >> >> Sure. I will fix this in v2. >> >>>> support for creating virtual Ethernet devices over RPMSG channels, >>>> allowing user-space programs to send and receive messages using a >>>> standard Ethernet protocol. The driver includes message handling, >>>> probe, and remove functions, along with necessary data structures. >>>> >>> >>> >>> ... >>> >>>> + >>>> +/** >>>> + * rpmsg_eth_get_shm_info - Get shared memory info from device tree >>>> + * @common: Pointer to rpmsg_eth_common structure >>>> + * >>>> + * Return: 0 on success, negative error code on failure >>>> + */ >>>> +static int rpmsg_eth_get_shm_info(struct rpmsg_eth_common *common) >>>> +{ >>>> + struct device_node *peer; >>>> + const __be32 *reg; >>>> + u64 start_address; >>>> + int prop_size; >>>> + int reg_len; >>>> + u64 size; >>>> + >>>> + peer = of_find_node_by_name(NULL, "virtual-eth-shm"); >>> >>> >>> This is new ABI and I do not see earlier patch documenting it. >>> >>> You cannot add undocumented ABI... but even if you documented it, I am >>> sorry, but I am pretty sure it is wrong. Why are you choosing random >>> nodes just because their name by pure coincidence is "virtual-eth-shm"? >>> I cannot name my ethernet like that? >>> >> >> This series adds a new virtual ethernet driver. The tx / rx happens in a >> shared memory block. I need to have a way for the driver to know what is >> the address / size of this block. This driver can be used by any >> vendors. The vendors can create a new node in their dt and specify the >> base address / size of the shared memory block. >> >> I wanted to keep the name of the node constant so that the driver can >> just look for this name and then grab the address and size. > > You should not. > >> >> I can create a new binding file for this but I didn't create thinking >> it's a virtual device not a physical and I wasn't sure if bindings can >> be created for virtual devices. > > So you added undocumented ABI intentionally, sorry, that's a no go. > >> >> In my use case, I am reserving this shared memory and during reserving I >> named the node "virtual-eth-shm". The memory is reserved by the >> ti_k3_r5_remoteproc.c driver. The DT change is not part of this series >> but can be found >> https://gist.github.com/danish-ti/cdd10525ad834fdb20871ab411ff94fb >> >> The idea is any vendor who want to use this driver, should name their dt >> node as "virtual-eth-shm" (if they also need to reserve the memory) so >> that the driver can take the address from DT and use it for tx / rx. >> >> If this is not the correct way, can you please let me know of some other >> way to handle this. >> >> One idea I had was to create a new binding for this node, and use >> compatible string to access the node in driver. But the device is >> virtual and not physical so I thought that might not be the way to go so >> I went with the current approach. > > virtual devices do not go to DTS anyway. How do you imagine this works? > You add it to DTS but you do not add bindings and you expect checks to > succeed? > > Provide details how you checked your DTS compliance. > > This is my device tree patch [1]. I ran these two commands before and after applying the patch and checked the diff. make dt_binding_check make dtbs_check I didn't see any new error / warning getting introduced due to the patch After applying the patch I also ran, make CHECK_DTBS=y ti/k3-am642-evm.dtb I still don't see any warnings / error. If you look at the DT patch, you'll see I am adding a new node in the `reserved-memory`. I am not creating a completely new undocumented node. Instead I am creating a new node under reserved-memory as the shared memory used by rpmsg-eth driver needs to be reserved first. This memory is reserved by the ti_k3_r5_remoteproc driver by k3_reserved_mem_init(). It's just that I am naming this node as "virtual-eth-shm@a0400000" and then using the same name in driver to get the base_address and size mentioned in this node. > > Best regards, > Krzysztof [1] https://gist.githubusercontent.com/danish-ti/fd3e630227ae5b165e12eabd91b0dc9d/raw/67d7c15cd1c47a29c0cfd3674d7cd6233ef1bea5/0001-arch-arm64-dts-k3-am64-Add-shared-memory-node.patch -- Thanks and Regards, Danish
