For the driver rtl8192cu (a USB wireless device), the current version loads the
15KB firmware asynchronously one 32-bit quantity at a time. Although
inefficient. this method works with USB 1.1 and USB 2.0 adapters; however, it
fails on at least one USB 3.0 adapter with "xhci_hcd 0000:05:00.0: ERROR no room
on ep ring" errors.
These errors are believed to arise from small, fixed-size ep rings. There is a
vendor driver that works with that same hardware. The major difference is that
it uses synchronous block writes of 254 bytes. When I tried this with the
in-kernel driver, each block write yields a warning as shown below:
nommu_map_single: overflow 41000340d020+254 of device mask ffffffff
The only remaining difference between the two drivers is that the vendor version
uses firmware hard coded into the driver while the kernel version uses a file
from /lib/firmware.
My cpu info is:
----- /proc/cpuinfo -----
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 104
model name : AMD Turion(tm) 64 X2 TL-60
stepping : 2
cpu MHz : 2000.000
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov
pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm
3dnowext 3dnow rep_good nopl extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic
cr8_legacy 3dnowprefetch lbrv
bogomips : 4001.06
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc 100mhzsteps
Could someone please explain the meaning of the above messages? Even with them
present, the device works.
Thanks,
Larry
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