On Sat, 2018-03-17 at 09:50 -0400, Alan Stern wrote: > On Sat, 17 Mar 2018, Benjamin Herrenschmidt wrote: > > > On Fri, 2018-03-16 at 16:56 -0400, Alan Stern wrote: > > > On Fri, 16 Mar 2018, Benjamin Herrenschmidt wrote: > > > > > > > On Thu, 2018-03-15 at 08:03 +1100, Benjamin Herrenschmidt wrote: > > > > > > > Do you have more comments for the rest of the driver or that's it ? > > > > > > > > > > > > so far, that's it. > > > > > > > > > > Ok. I'll re-send. > > > > > > > > So I'll resend in a minute, doing a few more tests, however, I've > > > > noticed something which I wont' have time to track down til at > > > > best next week, I wonder if it's normal/expected. > > > > > > > > If I just create a mass storage function set to be "removable" and > > > > "cdrom" with no file attached, and enable it, I get an endless stream > > > > of resets. It looks like the host constantly does USB resets. > > > > > > That's not why I get. There's an endless stream of messages, but it > > > doesn't include any resets. Just command failures and endpoint halts. > > > For example: > > > > .../... > > > > In my case, I was getting resets on the host: > .../... > Output from usbmon could help. So that ended up being a bug in my UDC driver. For IN requests I had a problem with 0-length requests when enabling the multi-descriptor mode in the EP which seems to affect some MODE_SENSE responses among others. I fixed that and now see only the silent errors you mentioned. Felipe, I'll send a respin of the driver with a fix tomorrow. .../... > Maybe... Even after cdrom support was added to the gadget, the scope > was limited. It was intended to emulate _only_ a CD drive, not a DVD > drive. > > Also, if I'm not mistaken, the commands that the emulation doesn't > handle are all optional. Right. One low hanging fruit seems to be GET_EVENT_STATUS_NOTIFICATION (0x4a). I'll look into it in my copious spare time ;-) There are a few more, which as long as we only support "read only" CD/DVD should be fairly easy to deal with. Cheers, Ben. > Alan Stern > > > The Aspeed chip is a BMC chip, ie server management processor, and is > > connected via the USB gadget to the actual server (the host). One of > > the usage scenario here is to use USB gadget to present distro ISOs as > > USB CD/DVDs to the host for remote provisioning (sourced over the > > network via something like nbd). > > > > Note that due to the limitation of having to use a file or a block > > device, we might end up doing a userspace CDROM emulation instead that > > can source ISOs via things like HTTPS instead, but initially the above > > is what we are toying with. > > > > Cheers, > > Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
