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Commit f0394621 authored by Ondrej Zary's avatar Ondrej Zary Committed by Martin K. Petersen
Browse files

ncr5380: Fix pseudo DMA transfers on 53C400 



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: default avatarOndrej Zary <linux@rainbow-software.org>
Signed-off-by: default avatarFinn Thain <fthain@telegraphics.com.au>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 3d07d22b

drivers/scsi/g_NCR5380.c

+4 −0
Original line number Diff line number Diff line
@@ -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;

}