Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757321Ab2J1Xbz (ORCPT ); Sun, 28 Oct 2012 19:31:55 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42234 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757052Ab2J1X2a (ORCPT ); Sun, 28 Oct 2012 19:28:30 -0400 Message-Id: <20121028231545.002108441@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Sun, 28 Oct 2012 23:16:02 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Feng Tang , Len Brown Subject: [ 026/105] ACPI: EC: Make the GPE storm threshold a module parameter In-Reply-To: <20121028231536.970033833@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3279 Lines: 81 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Feng Tang commit a520d52e99b14ba7db135e916348f12f2a6e09be upstream. The Linux EC driver includes a mechanism to detect GPE storms, and switch from interrupt-mode to polling mode. However, polling mode sometimes doesn't work, so the workaround is problematic. Also, different systems seem to need the threshold for detecting the GPE storm at different levels. ACPI_EC_STORM_THRESHOLD was initially 20 when it's created, and was changed to 8 in 2.6.28 commit 06cf7d3c7 "ACPI: EC: lower interrupt storm threshold" to fix kernel bug 11892 by forcing the laptop in that bug to work in polling mode. However in bug 45151, it works fine in interrupt mode if we lift the threshold back to 20. This patch makes the threshold a module parameter so that user has a flexible option to debug/workaround this issue. The default is unchanged. This is also a preparation patch to fix specific systems: https://bugzilla.kernel.org/show_bug.cgi?id=45151 Signed-off-by: Feng Tang Signed-off-by: Len Brown Signed-off-by: Ben Hutchings --- drivers/acpi/ec.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c index 7edaccc..615264c 100644 --- a/drivers/acpi/ec.c +++ b/drivers/acpi/ec.c @@ -71,9 +71,6 @@ enum ec_command { #define ACPI_EC_UDELAY_GLK 1000 /* Wait 1ms max. to get global lock */ #define ACPI_EC_MSI_UDELAY 550 /* Wait 550us for MSI EC */ -#define ACPI_EC_STORM_THRESHOLD 8 /* number of false interrupts - per one transaction */ - enum { EC_FLAGS_QUERY_PENDING, /* Query is pending */ EC_FLAGS_GPE_STORM, /* GPE storm detected */ @@ -87,6 +84,15 @@ static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY; module_param(ec_delay, uint, 0644); MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes"); +/* + * If the number of false interrupts per one transaction exceeds + * this threshold, will think there is a GPE storm happened and + * will disable the GPE for normal transaction. + */ +static unsigned int ec_storm_threshold __read_mostly = 8; +module_param(ec_storm_threshold, uint, 0644); +MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm"); + /* If we find an EC via the ECDT, we need to keep a ptr to its context */ /* External interfaces use first EC only, so remember */ typedef int (*acpi_ec_query_func) (void *data); @@ -319,7 +325,7 @@ static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t) msleep(1); /* It is safe to enable the GPE outside of the transaction. */ acpi_enable_gpe(NULL, ec->gpe); - } else if (t->irq_count > ACPI_EC_STORM_THRESHOLD) { + } else if (t->irq_count > ec_storm_threshold) { pr_info(PREFIX "GPE storm detected, " "transactions will use polling mode\n"); set_bit(EC_FLAGS_GPE_STORM, &ec->flags); -- 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/