From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754599AbdA3Vw2 (ORCPT ); Mon, 30 Jan 2017 16:52:28 -0500 Received: from smtp-1b.atlantis.sk ([80.94.52.26]:42675 "EHLO smtp-1b.atlantis.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754240AbdA3Vw0 (ORCPT ); Mon, 30 Jan 2017 16:52:26 -0500 From: Ondrej Zary To: Finn Thain Subject: Re: [PATCH 0/6] ncr5380: Miscellaneous minor patches Date: Mon, 30 Jan 2017 22:52:12 +0100 User-Agent: KMail/1.9.10 (enterprise35 0.20100827.1168748) Cc: "James E.J. Bottomley" , "Martin K. Petersen" , Michael Schmitz , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <201701282244.40207.linux@rainbow-software.org> In-Reply-To: X-KMail-QuotePrefix: > MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201701302252.13124.linux@rainbow-software.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sunday 29 January 2017 02:05:02 Finn Thain wrote: > On Sat, 28 Jan 2017, Ondrej Zary wrote: > > On Monday 16 January 2017 00:50:57 Finn Thain wrote: > > > This series removes some unused code and related comments, addresses > > > the warnings generated by 'make W=1' and 'make C=1' and fixes a > > > theoretical bug in the bus reset method in atari_scsi. > > > > > > There's also a patch to add a missing error check during target > > > selection. The only target I tested was a QUANTUM DAYTONA514S disk as > > > that's all I have access to right now. Some testing with other targets > > > would be prudent. > > > > > > Michael, Ondrej, can I get you to review/test please? > > > > Tested on HP C2502 (53C400A chip), Canon FG2-5202 (53C400 chip), > > DTC-3181L (DTCT-436P chip) and MS-PNR (53C400A chip) ISA cards - > > everything works fine! > > > > Targets tested: > > QUANTUM LP240S GM240S01X > > IBM DORS-32160 > > IBM 0663L12 > > > > Thanks. > > > > Tested-by: Ondrej Zary > > Very helpful. Thank you, Ondrej. Also tested two CD-ROM drives and they didn't work (machine hangs). They didn't work before and looks like they never worked with PDMA. The fundamental problem of PDMA is that it either transfers all required data or it breaks horribly. Even when I added timeouts to the possibly infinite loops (to avoid hangs), the chip remained in some bad state. Sometimes the 53C80 gated IRQ check triggers. This can be hopefully fixed but there is a HW limitation: if less than 128 bytes were read from SCSI device, they get lost in chip buffer (the 128B buffers don't swap until full). Fortunately, most of the requests for too much data are bogus. The problem is that generic_NCR5380_dma_xfer_len() uses cmd->transfersize which seems to be wrong. All other NCR5380 drivers use cmd->SCp.this_residual. This is also why rescan-scsi-bus hangs (cmd->transfersize is 8192 but cmd->SCp.this_residual is only 96). This quick fix allows CD-ROM and also rescan-scsi-bus to work. But it's not complete. Seems that we need: - fix pread and pwrite to terminate gracefully - something like atari_scsi_dma_xfer_len to allow DMA only for block commands @@ -588,22 +619,19 @@ static inline int generic_NCR5380_pwrite(struct NCR5380_hostdata *hostdata, static int generic_NCR5380_dma_xfer_len(struct NCR5380_hostdata *hostdata, struct scsi_cmnd *cmd) { - int transfersize = cmd->transfersize; + int transfersize = cmd->SCp.this_residual; if (hostdata->flags & FLAG_NO_PSEUDO_DMA) return 0; - /* Limit transfers to 32K, for xx400 & xx406 - * pseudoDMA that transfers in 128 bytes blocks. - */ - if (transfersize > 32 * 1024 && cmd->SCp.this_residual && - !(cmd->SCp.this_residual % transfersize)) - transfersize = 32 * 1024; - /* 53C400 datasheet: non-modulo-128-byte transfers should use PIO */ if (transfersize % 128) transfersize = 0; + /* Limit transfers to 32K */ + if (transfersize > 32 * 1024) + transfersize = 32 * 1024; + return transfersize; } -- Ondrej Zary