linux-kernel - Re: [PATCH] acpi/battery: fix wrong value of capacity_now reported by few battery types when fully charged (resend)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20140617201359.GA6988@dashie>
Date:	Tue, 17 Jun 2014 22:14:00 +0200
From:	Josef Gajdusek <atx@....name>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] acpi/battery: fix wrong value of capacity_now reported
 by few battery types when fully charged (resend)

It seems that some batteries (noticed on DELL JYPJ136) assume 
capacity_now = design_capacity when fully charged. This causes 
reported capacity to suddenly jump to >full_charge_capacity (and that 
means capacity reported to userspace is >100% and incorrect) 
values after 99%. This patch attempts to detect this bug, notifies 
userspace and trims the value to full_charge_capacity.

Signed-off-by: Josef Gajdusek <atx@....name>
---
> 
> But it still is necessary to check if battery->full_charge_capacity is
> not ACPI_BATTERY_VALUE_UNKNOWN, isn't it?
> 

Fixed, my mistake. When changing the checks, I somehow missed that the values 
are not unsigned.

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index e48fc98..2e8f699 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -532,6 +532,19 @@ static int acpi_battery_get_state(struct acpi_battery *battery)
 			" invalid.\n");
 	}
 
+	/* When fully charged, some batteries wrongly report
+	 * capacity_now = design_capacity instead of = full_charge_capacity
+	 */
+	if (battery->capacity_now > battery->full_charge_capacity &&
+		battery->full_charge_capacity != ACPI_BATTERY_VALUE_UNKNOWN) {
+		battery->capacity_now = battery->full_charge_capacity;
+		printk_once(KERN_WARNING FW_BUG
+			"battery: reported current charge level (%d) "
+			"is higher than reported maximum charge level (%d)."
+			"This is normal on some systems.\n",
+			battery->capacity_now, battery->full_charge_capacity);
+	}
+
 	if (test_bit(ACPI_BATTERY_QUIRK_PERCENTAGE_CAPACITY, &battery->flags)
 	    && battery->capacity_now >= 0 && battery->capacity_now <= 100)
 		battery->capacity_now = (battery->capacity_now *

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/