From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ondrej Zary Subject: [PATCH 72/71] ncr5380: Fix pseudo-DMA Date: Wed, 25 Nov 2015 22:34:42 +0100 Message-ID: <1448487282-31766-1-git-send-email-linux@rainbow-software.org> References: <20151118083455.331768508@telegraphics.com.au> Return-path: In-Reply-To: <20151118083455.331768508@telegraphics.com.au> Sender: linux-m68k-owner@vger.kernel.org To: Finn Thain , Michael Schmitz , linux-m68k@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-scsi@vger.kernel.org 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 --- drivers/scsi/g_NCR5380.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c index 0daffe2..a9a237f 100644 --- a/drivers/scsi/g_NCR5380.c +++ b/drivers/scsi/g_NCR5380.c @@ -703,6 +703,10 @@ 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; } -- Ondrej Zary