05000450 DESCRIPTION: DMA mode 1 allows large size transfers to generate a single interrupt at the end of the entire transfer. The transfer is split up in packets of length specified in the Maximum Packet Size field for that endpoint. If the transfer size is not an integer multiple of the Maximum Packet Size, there a short packet will be present at the end of the transfer. Under certain conditions this packet may be corrupted in the USB FIFO. WORKAROUND: Use DMA mode 1 to transfer (n* Maximum Packet Size) and schedule DMA mode 0 to transfer the short packet. Find details here https://docs.blackfin.uclinux.org/doku.php?id=infra:anomalies:05-00-0450 Sonic -----Original Message----- From: Sergei Shtylyov [mailto:sshtylyov@xxxxxxxxxxxxx] Sent: Wednesday, June 03, 2009 5:14 PM To: Mike Frysinger Cc: felipe.balbi@xxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx; uclinux-dist-devel@xxxxxxxxxxxxxxxxxxxx; Zhang, Sonic Subject: Re: [PATCH 8/9] USB: musb: add notes for Blackfin anomaly 05000450 Hello. Mike Frysinger wrote: > From: Sonic Zhang <sonic.zhang@xxxxxxxxxx> > > Add some helpful notes about how the driver works around anomaly > 05000450 (USB DMA Mode 1 Short Packet Data Corruption). > > Signed-off-by: Sonic Zhang <sonic.zhang@xxxxxxxxxx> > Signed-off-by: Mike Frysinger <vapier@xxxxxxxxxx> > --- > drivers/usb/musb/blackfin.h | 6 ++++++ > 1 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/drivers/usb/musb/blackfin.h b/drivers/usb/musb/blackfin.h > index 159fdea..ba5e606 100644 > --- a/drivers/usb/musb/blackfin.h > +++ b/drivers/usb/musb/blackfin.h > @@ -14,6 +14,12 @@ > * Blackfin specific definitions > */ > > +/* Anomaly notes: > + * 05000450 - MUSB driver is degined to transfer buffer of > +N*maxpacket size > s/degined/designed/? > + * in DMA mode 1 and leave rest data to the next transfer in DMA > And what's the anomaly? > + * mode 0. > +*/ > Documentation/CodingStyle, chapter 8: The preferred style for long (multi-line) comments is: /* * This is the preferred style for multi-line * comments in the Linux kernel source code. * Please use it consistently. * * Description: A column of asterisks on the left side, * with beginning and ending almost-blank lines. */ WBR, Sergei -- 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
