On Tue, Dec 05, 2023 at 05:15:33PM +0530, Ayush Singh wrote:
On 12/5/23 05:44, Greg KH wrote:
On Mon, Dec 04, 2023 at 09:58:55PM +0530, Ayush Singh wrote:
On 12/4/23 19:42, Johan Hovold wrote:
On Mon, Dec 04, 2023 at 06:40:06PM +0530, Ayush Singh wrote:
Ensure that the following values are little-endian:
- header->pad (which is used for cport_id)
- header->size
Fixes: ec558bbfea67 ("greybus: Add BeaglePlay Linux Driver") Reported-by: kernel test robot yujie.liu@intel.com Closes: https://lore.kernel.org/r/202311072329.Xogj7hGW-lkp@intel.com/ Signed-off-by: Ayush Singh ayushdevel1325@gmail.com
V3:
- Fix endiness while sending.
V2: https://lists.linaro.org/archives/list/greybus-dev@lists.linaro.org/thread/L...
- Ensure endianess for header->pad
V1: https://lists.linaro.org/archives/list/greybus-dev@lists.linaro.org/message/...
drivers/greybus/gb-beagleplay.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/greybus/gb-beagleplay.c b/drivers/greybus/gb-beagleplay.c index 43318c1993ba..8b21c3e1e612 100644 --- a/drivers/greybus/gb-beagleplay.c +++ b/drivers/greybus/gb-beagleplay.c @@ -93,9 +93,9 @@ static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len) memcpy(&cport_id, hdr->pad, sizeof(cport_id)); dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
hdr->operation_id, hdr->type, cport_id, hdr->result);
hdr->operation_id, hdr->type, le16_to_cpu(cport_id), hdr->result);
- greybus_data_rcvd(bg->gb_hd, cport_id, buf, len);
- greybus_data_rcvd(bg->gb_hd, le16_to_cpu(cport_id), buf, len);
This looks broken; a quick against mainline (and linux-next) check shows cport_id to be u16.
I think you want get_unaligned_le16() or something instead of that memcpy() above.
Thanks, will do.
But that just begs the question: why has this driver repurposed the pad bytes like this? The header still says that these shall be set to zero.
So, the reason is multiplexing. The original gbridge setup used to do this, so I followed it when I moved gbridge to the coprocessor (during GSoC).
Using the padding for storing cport information allows not having to wrap the message in some other format at the two transport layers (UART and TCP sockets) beagle connect is using.This also seems better than trying to do something bespoke, especially since the padding bytes are not being used for anything else.
The initial spec was for project Ara (modular smartphone), so the current use for IoT is significantly different from the initial goals of the protocol. Maybe a future version of the spec can be more focused on IoT, but that will probably only happen once it has proven somewhat useful in this space.
Please don't violate the spec today this way, I missed that previously, that's not ok. We can change the spec for new things if you need it, but to not follow it, and still say it is "greybus" isn't going to work and will cause problems in the long-run.
Should I just disable the driver for now until this is fixed up?
thanks,
greg k-h
Well, I will look into some ways to pass along the cport information (maybe using a wrapper over greybus message) for now. However, I would prefer having some bytes in greybus messages reserved for passing around this information in a transport agnostic way.
I'm confused, what exactly is needed here to be sent that isn't in the existing message definition.
And as to your original statement, the protocol definition was not designed for any specific use case that would make IoT "special" here that I can see. It was designed to provide a discoverable way to describe and control hardware on an unknown transport layer for devices that are not discoverable by definition (serial, i2c, etc.)
The fact that we implemented this on both USB and unipro successfully provided that the transport layer for the data should be working and agnositic.
thanks,
greg k-h