Messages in this thread | | | Date | Tue, 24 May 2022 15:23:32 +0300 | From | Eli Billauer <> | Subject | Re: [PATCH v2] char: xillybus: Check endpoint type before allocing |
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On 23/05/22 20:15, Greg KH wrote: >> Rather, it works like this: The driver uses the EP 1 IN and OUT endpoints to >> > query the device for a data structure, which contains information on the >> > device's communication channels. The driver sets up device files >> > accordingly, and it also gets informed on which bulk OUT endpoints are >> > present. >> > >> > For what it's worth, I think it's fairly safe to assume that if a device >> > returns a legal data structure (which passes a CRC test), it's a XillyUSB >> > device. >> > Why? You still need to verify that the requested endpoints match up > with what the device really has. > OK. So to summarize:
EP 1 IN and EP 1 OUT are always present in XillyUSB devices.
On top of these, there might be additional bulk OUT endpoints. The driver resolves which ones in setup_channels(), by scanning a data blob it has received from the device. This takes place in the for-loop inside this function. When (out_desc & 0x80) is true for a given @i in the loop, the device has a bulk OUT endpoint with address i+2 (e.g. if this condition is met for i==2, the device has a bulk OUT EP 4).
So it seems like setup_channels() would be the right place to make this check, since it's called during the device's probe.
I guess it would likewise make sense to check for EP 1 IN and OUT in xillyusb_setup_base_eps().
Thanks, Eli
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