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nusb: provide language id when reading string descriptors (thanks ftrvxmtrx)

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there are devices which do not return a string if used
with invalid language id, so at least try to use the first
one and choose english if failed.

this fixes CDC ethernet for N900
This commit is contained in:
cinap_lenrek 2012-12-10 10:36:53 +01:00
parent 8f0ed00420
commit 3971337d13
1 changed files with 14 additions and 1 deletions
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15
sys/src/cmd/nusb/lib/dev.c
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@ -205,13 +205,26 @@ char*
loaddevstr(Dev *d, int sid)
{
uchar buf[128];
int langid;
int type;
int nr;
if(sid == 0)
return estrdup("none");
type = Rd2h|Rstd|Rdev;
nr=usbcmd(d, type, Rgetdesc, Dstr<<8|sid, 0, buf, sizeof(buf));
/*
* there are devices which do not return a string if used
* with invalid language id, so at least try to use the first
* one and choose english if failed
*/
nr=usbcmd(d, type, Rgetdesc, Dstr<<8, 0, buf, sizeof(buf));
if(nr < 4)
langid = 0x0409; // english
else
langid = buf[3]<<8|buf[2];
nr=usbcmd(d, type, Rgetdesc, Dstr<<8|sid, langid, buf, sizeof(buf));
return mkstr(buf, nr);
}