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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: Finn Thain <fthain@telegraphics.com.au>
Tested-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ondrej Zary 2017-07-03 03:59:06 -04:00 committed by Martin K. Petersen
parent 99a974e6b8
commit facfc963ae
1 changed files with 11 additions and 2 deletions
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13
drivers/scsi/g_NCR5380.c
View File

@ -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);
}