Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757039Ab3JNQS6 (ORCPT ); Mon, 14 Oct 2013 12:18:58 -0400 Received: from mga14.intel.com ([143.182.124.37]:41861 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751018Ab3JNQS4 (ORCPT ); Mon, 14 Oct 2013 12:18:56 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.93,493,1378882800"; d="scan'208";a="374537588" Subject: [PATCH 2] libahci: fix turning on LEDs in ahci_start_port() To: tj@kernel.org From: Lukasz Dorau Cc: linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 14 Oct 2013 18:18:53 +0200 Message-ID: <20131014161853.20775.1487.stgit@gklab-154-244.igk.intel.com> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2104 Lines: 53 If EM Transmit bit is busy during init ata_msleep() is called. It is wrong - msleep() should be used instead of ata_msleep(), because if EM Transmit bit is busy for one port, it will be busy for all other ports too, so using ata_msleep() causes wasting tries for another ports. The most common scenario looks like that now (six ports try to transmit a LED meaasege): - port #0 tries for the 1st time and succeeds - ports #1-5 try for the 1st time and sleeps - port #1 tries for the 2nd time and succeeds - ports #2-5 try for the 2nd time and sleeps - port #2 tries for the 3rd time and succeeds - ports #3-5 try for the 3rd time and sleeps - port #3 tries for the 4th time and succeeds - ports #4-5 try for the 4th time and sleeps - port #4 tries for the 5th time and succeeds - port #5 tries for the 5th time and sleeps At this moment port #5 wasted all its five tries and failed to initialize. Because there are only 5 (EM_MAX_RETRY) tries available usually only five ports succeed to initialize. The sixth port and next ones usually will fail. If msleep() is used instead of ata_msleep() the first port succeeds to initialize in the first try and next ones usually succeed to initialize in the second try. Signed-off-by: Lukasz Dorau --- drivers/ata/libahci.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c index acfd0f7..8fb7092 100644 --- a/drivers/ata/libahci.c +++ b/drivers/ata/libahci.c @@ -779,7 +779,11 @@ static void ahci_start_port(struct ata_port *ap) emp->led_state, 4); if (rc == -EBUSY) - ata_msleep(ap, 1); + /* Do not release ownership of @ap's EH, + * because EM Transmit bit is busy for + * all ports sharing the @ap->host. + */ + msleep(1); else break; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/