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Commit facfc963 authored by Ondrej Zary's avatar Ondrej Zary Committed by Martin K. Petersen
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scsi: g_NCR5380: Two DTC436 PDMA workarounds 



Limit PDMA send to 512 B to avoid data corruption on DTC3181E. The
corruption is always the same: one byte missing at the beginning of a
128 B block. It happens only with slow Quantum LPS 240 drive, not with
faster IBM DORS-32160. It's not clear what causes this. Documentation
for the DTC436 chip has not been made available.

Signed-off-by: default avatarFinn Thain <fthain@telegraphics.com.au>
Tested-by: default avatarOndrej Zary <linux@rainbow-software.org>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 99a974e6

drivers/scsi/g_NCR5380.c

+11 −2
Original line number Diff line number Diff line
@@ -45,7 +45,8 @@ 
	int c400_blk_cnt; \

	int c400_host_buf; \

	int io_width; \

	int pdma_residual

	int pdma_residual; \

	int board



#define NCR5380_dma_xfer_len            generic_NCR5380_dma_xfer_len

#define NCR5380_dma_recv_setup          generic_NCR5380_precv
@@ -316,6 +317,7 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt, 
	}

	hostdata = shost_priv(instance);



	hostdata->board = board;

	hostdata->io = iomem;

	hostdata->region_size = region_size;
@@ -492,6 +494,8 @@ static void wait_for_53c80_access(struct NCR5380_hostdata *hostdata) 
	int count = 10000;



	do {

		if (hostdata->board == BOARD_DTC3181E)

			udelay(4); /* DTC436 chip hangs without this */

		if (NCR5380_read(hostdata->c400_ctl_status) & CSR_53C80_REG)

			return;

	} while (--count > 0);
@@ -665,7 +669,12 @@ static int generic_NCR5380_dma_xfer_len(struct NCR5380_hostdata *hostdata, 


	/* 53C400 datasheet: non-modulo-128-byte transfers should use PIO */

	if (transfersize % 128)

		transfersize = 0;

		return 0;



	/* Limit PDMA send to 512 B to avoid random corruption on DTC3181E */

	if (hostdata->board == BOARD_DTC3181E &&

	    cmd->sc_data_direction == DMA_TO_DEVICE)

		transfersize = min(cmd->SCp.this_residual, 512);



	return min(transfersize, DMA_MAX_SIZE);

}