diff options
Diffstat (limited to 'drivers/usb/host/ohci-sa1111.c')
| -rw-r--r-- | drivers/usb/host/ohci-sa1111.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/drivers/usb/host/ohci-sa1111.c b/drivers/usb/host/ohci-sa1111.c index feca826d3f6a..75c2b28b3379 100644 --- a/drivers/usb/host/ohci-sa1111.c +++ b/drivers/usb/host/ohci-sa1111.c @@ -203,6 +203,31 @@ static int ohci_hcd_sa1111_probe(struct sa1111_dev *dev) goto err1; } + /* + * According to the "Intel StrongARM SA-1111 Microprocessor Companion + * Chip Specification Update" (June 2000), erratum #7, there is a + * significant bug in the SA1111 SDRAM shared memory controller. If + * an access to a region of memory above 1MB relative to the bank base, + * it is important that address bit 10 _NOT_ be asserted. Depending + * on the configuration of the RAM, bit 10 may correspond to one + * of several different (processor-relative) address bits. + * + * Section 4.6 of the "Intel StrongARM SA-1111 Development Module + * User's Guide" mentions that jumpers R51 and R52 control the + * target of SA-1111 DMA (either SDRAM bank 0 on Assabet, or + * SDRAM bank 1 on Neponset). The default configuration selects + * Assabet, so any address in bank 1 is necessarily invalid. + * + * As a workaround, use a bounce buffer in addressable memory + * as local_mem, relying on ZONE_DMA to provide an area that + * fits within the above constraints. + * + * SZ_64K is an estimate for what size this might need. + */ + ret = usb_hcd_setup_local_mem(hcd, 0, 0, SZ_64K); + if (ret) + goto err1; + if (!request_mem_region(hcd->rsrc_start, hcd->rsrc_len, hcd_name)) { dev_dbg(&dev->dev, "request_mem_region failed\n"); ret = -EBUSY; |