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ncr5380: Fix pseudo DMA transfers on 53C400

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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@rainbow-software.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ondrej Zary 2016-01-03 16:06:14 +11:00 committed by Martin K. Petersen
parent 3d07d22b3d
commit f03946210d
1 changed files with 4 additions and 0 deletions
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4
drivers/scsi/g_NCR5380.c
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@ -702,6 +702,10 @@ static int generic_NCR5380_dma_xfer_len(struct scsi_cmnd *cmd)
!(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;
}