Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761971AbcJaIAD (ORCPT ); Mon, 31 Oct 2016 04:00:03 -0400 Received: from smtp-1b.atlantis.sk ([80.94.52.26]:41923 "EHLO smtp-1b.atlantis.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761929AbcJaIAC (ORCPT ); Mon, 31 Oct 2016 04:00:02 -0400 From: Ondrej Zary To: Finn Thain Subject: Re: [PATCH 3/3] NCR5380: Check for chip presence in NCR5380_init() Date: Mon, 31 Oct 2016 08:59:53 +0100 User-Agent: KMail/1.9.10 (enterprise35 0.20100827.1168748) Cc: Christoph Hellwig , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org References: <1477867203-7480-1-git-send-email-linux@rainbow-software.org> <1477867203-7480-3-git-send-email-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: <201610310859.53758.linux@rainbow-software.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1286 Lines: 38 On Monday 31 October 2016, Finn Thain wrote: > On Sun, 30 Oct 2016, Ondrej Zary wrote: > > Read back MODE_REG after writing it in NCR5380_init() to check if the > > chip is really there. > > > > This prevents hang when incorrect I/O address was specified by user. > > > > Signed-off-by: Ondrej Zary > > --- > > drivers/scsi/NCR5380.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/drivers/scsi/NCR5380.c b/drivers/scsi/NCR5380.c > > index 01c0027..ce3156d 100644 > > --- a/drivers/scsi/NCR5380.c > > +++ b/drivers/scsi/NCR5380.c > > @@ -495,6 +495,11 @@ static int NCR5380_init(struct Scsi_Host *instance, > > int flags) > > > > NCR5380_write(INITIATOR_COMMAND_REG, ICR_BASE); > > NCR5380_write(MODE_REG, MR_BASE); > > + /* check if the chip is really there */ > > + if (NCR5380_read(MODE_REG) != MR_BASE) { > > + NCR5380_exit(instance); > > + return -ENODEV; > > + } > > This doesn't belong in the core driver. Only the 5380 ISA drivers have > configurable base addresses. > > Also, MR_BASE == 0, so that test is likely to be ineffectual anyway. This > patch doesn't really add any value AFAICT. This fixes the most common problem: no device present at the specified I/O address, all reads result in 0xff. -- Ondrej Zary