From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S946422AbcJaUSz (ORCPT ); Mon, 31 Oct 2016 16:18:55 -0400 Received: from ns.gsystem.sk ([62.176.172.50]:36104 "EHLO gsystem.sk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S946328AbcJaUSt (ORCPT ); Mon, 31 Oct 2016 16:18:49 -0400 From: Ondrej Zary To: Christoph Hellwig Cc: Finn Thain , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/6] g_NCR5380: Check for chip presence before calling NCR5380_init() Date: Mon, 31 Oct 2016 21:18:29 +0100 Message-Id: <1477945112-25659-4-git-send-email-linux@rainbow-software.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1477945112-25659-1-git-send-email-linux@rainbow-software.org> References: <1477945112-25659-1-git-send-email-linux@rainbow-software.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Write and read back MODE_REG to check if the chip is really there before doing more initialization. This prevents hang when incorrect I/O address was specified by user (in the most common case where no device is present there so all reads result in 0xff). Signed-off-by: Ondrej Zary --- drivers/scsi/g_NCR5380.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/scsi/g_NCR5380.c b/drivers/scsi/g_NCR5380.c index 0d1f6ad..e713dba 100644 --- a/drivers/scsi/g_NCR5380.c +++ b/drivers/scsi/g_NCR5380.c @@ -322,6 +322,13 @@ static int generic_NCR5380_init_one(struct scsi_host_template *tpnt, } } + /* check if the chip is really there */ + NCR5380_write(MODE_REG, 0); + if (NCR5380_read(MODE_REG) != 0) { + ret = -ENODEV; + goto out_unregister; + } + ret = NCR5380_init(instance, flags | FLAG_LATE_DMA_SETUP); if (ret) goto out_unregister; -- Ondrej Zary