Re: [PATCH] usb: gadget: USB3 support to the legacy printer driver

[Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>]

On 11/18/2014 03:47 PM, Felipe Balbi wrote:
> Hi,
>
> On Tue, Nov 18, 2014 at 03:41:43PM -0500, Jorge Ramirez-Ortiz wrote:
>>>>> you have no clue what these mean, do you ? How about reading the USB
>>>>> specification of even http://www.beyondlogic.org/usbnutshell/usb1.shtml
>>>> Unfortunately I do.
>>>> It was easier to temporarily hack the driver code for a test - while I
>>>> was at it - rather than modifying the host code.
>>>> Since you asked for them, I though you would read the logs and wonder
>>>> where the funny ids where coming from.
>>> why do you even need to hack the host driver for these ? The driver
>>> shows a Printer Class interface and the linux host side driver should
>>> bind to it without any issues.
>> the hack was on the gadget side.
>>
>> the usbhost test code in charge of sending the file to the device had the wrong ids.
>> to save time -since I was modifying the gadget driver code and only for the
>> tests (it is not part of the final patch) - I hacked those ids on the printer.c
>> file.
>> but anyway. lets move on. I removed those, recompiled the usb host code and sent
>> the new traces.
> then the host side needs a fix because it shouldn't really care about
> the device ID, rather it should care about the class being printer.

absolutely.
however if you use libusb_open_device_with_vid_pid then well, these things happen...

>
>>>> That hack above would have given you an answer: so I kind of know what
>>>> the ids are for. honestly.  anyway, will send the new logs - it took
>>>> me a while to find and modify the host test code.
>>> Which host test code ? Why don't you just use lpr or even cat file >
>>> /dev/lp0 or something like that ?
>> it is some proprietary code that links libusb -part of a different project: it
>> was useful as it generated some metrics I was interested in.
> I would be surprised if lpr doesn't work for the same purpose.
>
>>>>> do you want to debug that and find the culprit since you're already at
>>>>> it ?
>>>> probably: I still need to get used to this process, thanks for bearing
>>>> with me on this.
>>> no problem.
>>>
>>>> I spoke to Ricardo Ribalda three months ago while I was doing this
>>>> stuff.  but yes, I might work on this -after I finish with this
>>>> patch!- since I have access to the hardware locally.
>>> cool, that'll help.
>> notice that the original PLX driver was still far from the theoretical 5Gbps
>> target (I was expecting to measure at least 3Gbps and could only get 1Gbps).
>> So 1Gbps should be the target to meet on the kernel.org net2280 - do you agree?
> this depends on a whole bunch of things. Mainline is a lot different
> from PLX's kernel tree, I'm sure.
>
> It also depends on how many PCIe lanes you're using. Just because USB3
> guarantees 5Gbps bandwidth, if you use a 1x PCIe connector, you'll never
> get that ;-)
>

yes, that is why I purchased a Lenovo ThinkServer TS140 just for this integration.
it has one x16 Gen3 PCIe slot, one x1 Gen2 PCIe and one x16 Gen2 PCIe (x4 signal).
so this should be enough.

on the host side, I have good server as well.
So really, there is no excuse to not get this right unless there is a problem in
the plx silicon but from the Windows based metrics that I saw I dont think so.
The only think I am missing is the USB3 analyzer I used to have in my previous
company.