>-----Original Message----- >From: Felipe Balbi [mailto:felipe.balbi@xxxxxxxxx] >Sent: Wednesday, December 23, 2009 5:45 PM >To: ext Mike Frysinger >Cc: linux-usb@xxxxxxxxxxxxxxx; Balbi Felipe >(Nokia-D/Helsinki); uclinux-dist-devel@xxxxxxxxxxxxxxxxxxxx; Cai, Cliff >Subject: Re: [PATCH 1/6] [local/generalize] USB: musb: >workaround RX DMA hang anomaly by disabling double buffer mode > >Hi, > >On Thu, Dec 24, 2009 at 06:05:55AM +0100, ext Mike Frysinger wrote: >>From: Cliff Cai <cliff.cai@xxxxxxxxxx> >> >>Due to some anomalies, utilizing DMA double buffer may lead >to infinite >>hangs or data corruption. So when this anomalies exist, >disable double >>buffering mode. >> >>Signed-off-by: Cliff Cai <cliff.cai@xxxxxxxxxx> >>Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx> > >I believe blackfin doesn't have dynamic fifo sizing and double >buffering is enabled on the hw table ? > >I've seen data corruption when using double buffering also >with dynamic fifo sizing and that's why none of the fifo >tables have double buffering enabled. > >this tells me that we really can't trust musb's double >buffering at all and we can make a check based on the rtl >revision. At least until rtl1.9 we can't use double buffering, >no matter what the fifo table or hardware ep configuration says. Exactly,Blackfin doesn't have dynamic fifo sizing,and since the BULK EP has a 1024 bytes fifo,double buffering is enabled by default. Cliff -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
