linux-kernel - [PATCH v2] leds: pca963x: Fix open-drain initialization

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-next>] [day] [month] [year] [list]

Message-ID: <20191118210255.GA99907@majorz.localdomain>
Date:   Mon, 18 Nov 2019 23:02:55 +0200
From:   Zahari Petkov <zahari@...ena.io>
To:     Pavel Machek <pavel@....cz>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Dan Murphy <dmurphy@...com>
Cc:     linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        Zahari Petkov <zahari@...ena.io>
Subject: [PATCH v2] leds: pca963x: Fix open-drain initialization

Before commit bb29b9cccd95 ("leds: pca963x: Add bindings to invert
polarity") Mode register 2 was initialized directly with either 0x01
or 0x05 for open-drain or totem pole (push-pull) configuration.

Afterwards, MODE2 initialization started using bitwise operations on
top of the default MODE2 register value (0x05). Using bitwise OR for
setting OUTDRV with 0x01 and 0x05 does not produce correct results.
When open-drain is used, instead of setting OUTDRV to 0, the driver
keeps it as 1:

Open-drain: 0x05 | 0x01 -> 0x05 (0b101 - incorrect)
Totem pole: 0x05 | 0x05 -> 0x05 (0b101 - correct but still wrong)

Now OUTDRV setting uses correct bitwise operations for initialization:

Open-drain: 0x05 & ~0x04 -> 0x01 (0b001 - correct)
Totem pole: 0x05 | 0x04 -> 0x05 (0b101 - correct)

Additional MODE2 register definitions are introduced now as well.

Fixes: bb29b9cccd95 ("leds: pca963x: Add bindings to invert polarity")
Signed-off-by: Zahari Petkov <zahari@...ena.io>
---
 drivers/leds/leds-pca963x.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/leds-pca963x.c b/drivers/leds/leds-pca963x.c
index 4afc317901a8..66cdc003b8f4 100644
--- a/drivers/leds/leds-pca963x.c
+++ b/drivers/leds/leds-pca963x.c
@@ -40,6 +40,8 @@
 #define PCA963X_LED_PWM		0x2	/* Controlled through PWM */
 #define PCA963X_LED_GRP_PWM	0x3	/* Controlled through PWM/GRPPWM */
 
+#define PCA963X_MODE2_OUTDRV	0x04	/* Open-drain or totem pole */
+#define PCA963X_MODE2_INVRT	0x10	/* Normal or inverted direction */
 #define PCA963X_MODE2_DMBLNK	0x20	/* Enable blinking */
 
 #define PCA963X_MODE1		0x00
@@ -438,12 +440,12 @@ static int pca963x_probe(struct i2c_client *client,
 						    PCA963X_MODE2);
 		/* Configure output: open-drain or totem pole (push-pull) */
 		if (pdata->outdrv == PCA963X_OPEN_DRAIN)
-			mode2 |= 0x01;
+			mode2 &= ~PCA963X_MODE2_OUTDRV;
 		else
-			mode2 |= 0x05;
+			mode2 |= PCA963X_MODE2_OUTDRV;
 		/* Configure direction: normal or inverted */
 		if (pdata->dir == PCA963X_INVERTED)
-			mode2 |= 0x10;
+			mode2 |= PCA963X_MODE2_INVRT;
 		i2c_smbus_write_byte_data(pca963x->chip->client, PCA963X_MODE2,
 					  mode2);
 	}
-- 
2.24.0