Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751937AbdF2FYx (ORCPT ); Thu, 29 Jun 2017 01:24:53 -0400 Received: from kvm5.telegraphics.com.au ([98.124.60.144]:42416 "EHLO kvm5.telegraphics.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751591AbdF2FYU (ORCPT ); Thu, 29 Jun 2017 01:24:20 -0400 To: "James E.J. Bottomley" , "Martin K. Petersen" , Ondrej Zary Cc: , , Michael Schmitz Message-Id: <67f209cf84a47d4d4a3719eee9cd565fef5664a0.1498713600.git.fthain@telegraphics.com.au> In-Reply-To: References: From: Finn Thain Subject: [PATCH v5 4/6] g_NCR5380: Limit PDMA send to 512 B to avoid data corruption on DTC3181E Date: Thu, 29 Jun 2017 01:24:18 -0400 (EDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1651 Lines: 50 From: Ondrej Zary 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. Hence this workaround. Signed-off-by: Finn Thain --- drivers/scsi/g_NCR5380.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c index dedaed2d16e4..5fd227bb1830 100644 --- a/drivers/scsi/g_NCR5380.c +++ b/drivers/scsi/g_NCR5380.c @@ -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_pread @@ -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; @@ -644,7 +646,12 @@ 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); } -- 2.13.0