From: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx> Pseudo-DMA (PDMA) has been broken for ages, resulting in hangs on 53C400-based cards. According to 53C400 datasheet, PDMA transfer length must be a multiple of 128. Check if that's true and use PIO if it's not. This makes PDMA work on 53C400 (Canon FG2-5202). Signed-off-by: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> --- drivers/scsi/g_NCR5380.c | 4 ++++ 1 file changed, 4 insertions(+) Index: linux/drivers/scsi/g_NCR5380.c =================================================================== --- linux.orig/drivers/scsi/g_NCR5380.c 2016-01-03 16:04:38.000000000 +1100 +++ linux/drivers/scsi/g_NCR5380.c 2016-01-03 16:04:50.000000000 +1100 @@ -702,6 +702,10 @@ static int generic_NCR5380_dma_xfer_len( !(cmd->SCp.this_residual % transfersize)) transfersize = 32 * 1024; + /* 53C400 datasheet: non-modulo-128-byte transfers should use PIO */ + if (transfersize % 128) + transfersize = 0; + return transfersize; } -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
