Comment # 1 on bug 1169996 from Shung-Hsi Yu

Resolved with upstream commit f91a50d8b51b5c8ef1cfb08115a005bba4250507

> r8152: limit the RX buffer size of RTL8153A for USB 2.0
> 
> If the USB host controller is EHCI, the throughput is reduced from
> 300Mb/s to 60Mb/s, when the rx buffer size is modified from 16K to
> 32K.
> 
> According to the EHCI spec, the maximum size of the qTD is 20K.
> Therefore, when the driver uses more than 20K buffer, the latency
> time of EHCI would be increased. And, it let the RTL8153A get worse
> throughput.
> 
> However, the driver uses alloc_pages() for rx buffer, so I limit
> the rx buffer to 16K rather than 20K.