Martin Pieuchot <[email protected]> writes:
> On 15/04/15(Wed) 10:46, attila wrote:
>> Martin Pieuchot <[email protected]> writes:
>>
>> > On 14/04/15(Tue) 15:22, attila wrote:
>> >> Martin Pieuchot <[email protected]> writes:
>> >> >>
>> >> >> static const struct usb_devno ualea_devs[] = {
>> >> >> { USB_VENDOR_ARANEUS, USB_PRODUCT_ARANEUS_ALEA }
>> >> >> };
>> >> >
>> >> > Is it possible to match your device based on the content of the device
>> >> > descriptor instead of whitelisting IDs? Whitelisting means that if the
>> >> > company produce a compatible device with a new ID we'll need to modify
>> >> > the driver.
>> >> >
>> >>
>> >> Sadly, I don't think it is possible... you mean by looking at
>> >> bDeviceClass/bDeviceSubClass/bDeviceProtocol? He only gives me zeroes
>> >> [...]
>> >> Perhaps I am misunderstanding; is there something else in there I
>> >> could/should match on? I've changed the attach routine in the updated
>> >> version to check vendor/product/iface, at least.
>> >
>> > I was thinking at bInterfaceClass and bInterfaceProtocol but when they
>> > are both to "vendor defined" (255), matching against the ID is the right
>> > thing to do.
>> >
>> >> I looked and it appears that M_ZERO is used when allocating the memory
>> >> for all of these structures, so I take it that explicit zeroing of
>> >> things when tearing down is neither required nor desired? I removed
>> >> this kind of thing from ualea.c because it looked like it wasn't
>> >> necessary.
>> >
>> > That's right.
>> >
>> >> I'm attaching the updated driver.
>> >>
>> >> Thank you for the critique. I suppose I need to write a man page for
>> >> this as well... working on it.
>> >
>> > Perfect, I'll put it in tree together with your driver :)
>> >
>>
>> Man page attached. I am also attaching an updated copy of the driver
>> (only copyright changed).
>>
>> Thanks so much for your help. I look forward to contributing more.
>
> Committed thanks. I removed some unneeded headers and applied jmc@'s
> tweak.
>
> In the future I'd suggest you to send unified diff against the CVS tree,
> it's easier to apply & test!
After this was committed I received a critique of the driver from the
person behind the Alea II (Andreas Gustafsson) who made a few pretty
good points. He felt trying to pull all the entropy off of the device
that would theoretically be available every second was a losing
strategy for several reasons. Most importantly I ended up calling
add_true_randomness() in bursts of 3200 calls every trip through
ualea_task() whereas rnd_event_space[] in rnd.c only has 64 entries on
a 32bit machine (42 on amd64); this almost surely means that the vast
majority of my calls are no-ops... not so useful, it appears.
The attached diff cranks the buffer size way down and now we call
add_true_randomness() 32 times every 100ms. When I crank ALEA_MSECS
below 100ms I start to notice the load increases on the machine with
an Alea II plugged in. I guess this is because the stuff that happens
in ualea_task() happens in the context of a process and that process
always appears to be runnable when ALEA_MSECS is e.g. 10ms. I crank
the read timeout up to 5000ms because that's what he recommends in his
sample code; under normal circumstances we never time out.
The diff also explicitly looks for endpoint #1 because that's the
endpoint that Andreas says to use, not necc. the first one that I
find; as it turns out now the first one I find is the right one but
just to be safe it's better to check explicitly.
Maybe now this is closer to production-worthy. All feedback and
comments most welcome.
>
> Cheers,
> Martin
Pax, -A
--
[email protected] | http://trac.haqistan.net/~attila
keyid E6CC1EDB | 4D91 1B98 A210 1D71 2A0E AC29 9677 D0A6 E6CC 1EDB
Index: ualea.c
===================================================================
RCS file: /cvs/src/sys/dev/usb/ualea.c,v
retrieving revision 1.1
diff -u -p -r1.1 ualea.c
--- ualea.c 16 Apr 2015 08:55:21 -0000 1.1
+++ ualea.c 16 Apr 2015 20:34:59 -0000
@@ -36,9 +36,10 @@
#include <dev/rndvar.h>
#define ALEA_IFACE 0
+#define ALEA_ENDPOINT 1
#define ALEA_MSECS 100
-#define ALEA_READ_TIMEOUT 1000
-#define ALEA_BUFSIZ ((1024/8)*100) /* 100 kbits */
+#define ALEA_READ_TIMEOUT 5000
+#define ALEA_BUFSIZ 128
#define DEVNAME(_sc) ((_sc)->sc_dev.dv_xname)
@@ -101,7 +102,8 @@ ualea_attach(struct device *parent, stru
return;
}
if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_IN &&
- UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK) {
+ UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK &&
+ UE_GET_ADDR(ed->bEndpointAddress) == ALEA_ENDPOINT) {
ep_ibulk = ed->bEndpointAddress;
break;
}
