Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754960Ab2EHGvj (ORCPT ); Tue, 8 May 2012 02:51:39 -0400 Received: from webbox1416.server-home.net ([77.236.96.61]:35103 "EHLO webbox1416.server-home.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753142Ab2EHGvi (ORCPT ); Tue, 8 May 2012 02:51:38 -0400 From: Alexander Stein To: Richard Purdie Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] leds-pca955x: Fix race condition while setting brightness on several LEDs Date: Tue, 08 May 2012 08:51:35 +0200 Message-ID: <2641969.OTteIvR3hZ@ws-stein> User-Agent: KMail/4.8.0 (Linux/3.2.12-gentoo; KDE/4.8.1; x86_64; ; ) In-Reply-To: <4164556.rD0tn1gQO8@ws-stein> References: <1328705048-21073-1-git-send-email-alexander.stein@systec-electronic.com> <4164556.rD0tn1gQO8@ws-stein> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11038 Lines: 389 Any news/feedback on this? Regards, Alexander On Tuesday 20 March 2012 14:03:11, Alexander Stein wrote: > Any news/feedback on this? > > Regards, > Alexander > > Am Mittwoch, 8. Februar 2012, 13:44:08 schrieb Alexander Stein: > > When issuing the following command: > > for I in 0 1 2 3 4 5 6 7; do > > > > echo 0 > /sys/class/leds/pca955x\:${I}/brightness; > > > > done > > It is possible that all the pca955x_read_ls calls are done sequentially > > before any pca955x_write_ls call is done. This updates the LS only to the > > last LED update in its set. > > Fix this by using a global lock for the pca995x device during > > pca955x_led_work. Also used a struct for shared data bewteen all LEDs. > > > > Signed-off-by: Alexander Stein > > --- > > > > drivers/leds/leds-pca955x.c | 105 > > > > ++++++++++++++++++++++++++----------------- 1 files changed, 64 > > insertions(+), 41 deletions(-) > > > > diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c > > index dcc3bc3..2980d8e 100644 > > --- a/drivers/leds/leds-pca955x.c > > +++ b/drivers/leds/leds-pca955x.c > > @@ -101,11 +101,16 @@ static const struct i2c_device_id pca955x_id[] = { > > > > }; > > MODULE_DEVICE_TABLE(i2c, pca955x_id); > > > > -struct pca955x_led { > > +struct pca955x { > > + struct mutex lock; > > + struct pca955x_led *leds; > > > > struct pca955x_chipdef *chipdef; > > struct i2c_client *client; > > > > +}; > > + > > +struct pca955x_led { > > + struct pca955x *pca955x; > > > > struct work_struct work; > > > > - spinlock_t lock; > > > > enum led_brightness brightness; > > struct led_classdev led_cdev; > > int led_num; /* 0 .. 15 potentially */ > > > > @@ -128,7 +133,7 @@ static inline int pca95xx_num_led_regs(int bits) > > > > * Return an LED selector register value based on an existing one, with > > * the appropriate 2-bit state value set for the given LED number (0-3). > > */ > > > > -static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state) > > +static inline u8 pca955x_ledel(u8 oldval, int led_num, int state) > > > > { > > > > return (oldval & (~(0x3 << (led_num << 1)))) | > > > > ((state & 0x3) << (led_num << 1)); > > > > @@ -140,7 +145,7 @@ static inline u8 pca955x_ledsel(u8 oldval, int > > led_num, > > int state) */ > > > > static void pca955x_write_psc(struct i2c_client *client, int n, u8 val) > > { > > > > - struct pca955x_led *pca955x = i2c_get_clientdata(client); > > + struct pca955x *pca955x = i2c_get_clientdata(client); > > > > i2c_smbus_write_byte_data(client, > > > > pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n, > > > > @@ -156,7 +161,7 @@ static void pca955x_write_psc(struct i2c_client > > *client, int n, u8 val) */ > > > > static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val) > > { > > > > - struct pca955x_led *pca955x = i2c_get_clientdata(client); > > + struct pca955x *pca955x = i2c_get_clientdata(client); > > > > i2c_smbus_write_byte_data(client, > > > > pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n, > > > > @@ -169,7 +174,7 @@ static void pca955x_write_pwm(struct i2c_client > > *client, int n, u8 val) */ > > > > static void pca955x_write_ls(struct i2c_client *client, int n, u8 val) > > { > > > > - struct pca955x_led *pca955x = i2c_get_clientdata(client); > > + struct pca955x *pca955x = i2c_get_clientdata(client); > > > > i2c_smbus_write_byte_data(client, > > > > pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n, > > > > @@ -182,7 +187,7 @@ static void pca955x_write_ls(struct i2c_client > > *client, > > int n, u8 val) */ > > > > static u8 pca955x_read_ls(struct i2c_client *client, int n) > > { > > > > - struct pca955x_led *pca955x = i2c_get_clientdata(client); > > + struct pca955x *pca955x = i2c_get_clientdata(client); > > > > return (u8) i2c_smbus_read_byte_data(client, > > > > pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n); > > > > @@ -190,26 +195,31 @@ static u8 pca955x_read_ls(struct i2c_client *client, > > int n) > > > > static void pca955x_led_work(struct work_struct *work) > > { > > > > - struct pca955x_led *pca955x; > > + struct pca955x_led *pca955x_led; > > + struct pca955x *pca955x; > > > > u8 ls; > > int chip_ls; /* which LSx to use (0-3 potentially) */ > > int ls_led; /* which set of bits within LSx to use (0-3) */ > > > > - pca955x = container_of(work, struct pca955x_led, work); > > - chip_ls = pca955x->led_num / 4; > > - ls_led = pca955x->led_num % 4; > > + pca955x_led = container_of(work, struct pca955x_led, work); > > + pca955x = pca955x_led->pca955x; > > + > > + chip_ls = pca955x_led->led_num / 4; > > + ls_led = pca955x_led->led_num % 4; > > + > > + mutex_lock(&pca955x->lock); > > > > ls = pca955x_read_ls(pca955x->client, chip_ls); > > > > - switch (pca955x->brightness) { > > + switch (pca955x_led->brightness) { > > > > case LED_FULL: > > - ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON); > > + ls = pca955x_ledel(ls, ls_led, PCA955X_LS_LED_ON); > > > > break; > > > > case LED_OFF: > > - ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF); > > + ls = pca955x_ledel(ls, ls_led, PCA955X_LS_LED_OFF); > > > > break; > > > > case LED_HALF: > > - ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0); > > + ls = pca955x_ledel(ls, ls_led, PCA955X_LS_BLINK0); > > > > break; > > > > default: > > /* > > > > @@ -219,12 +229,15 @@ static void pca955x_led_work(struct work_struct > > *work) * OFF, HALF, or FULL. But, this is probably better than > > > > * just turning off for all other values. > > */ > > > > - pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness); > > - ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1); > > + pca955x_write_pwm(pca955x->client, 1, > > + 255 - pca955x_led->brightness); > > + ls = pca955x_ledel(ls, ls_led, PCA955X_LS_BLINK1); > > > > break; > > > > } > > > > pca955x_write_ls(pca955x->client, chip_ls, ls); > > > > + > > + mutex_unlock(&pca955x->lock); > > > > } > > > > static void pca955x_led_set(struct led_classdev *led_cdev, enum > > > > led_brightness value) @@ -233,7 +246,6 @@ static void > > pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness v > > > > pca955x = container_of(led_cdev, struct pca955x_led, led_cdev); > > > > - spin_lock(&pca955x->lock); > > > > pca955x->brightness = value; > > > > /* > > > > @@ -241,14 +253,13 @@ static void pca955x_led_set(struct led_classdev > > *led_cdev, enum led_brightness v * can sleep. > > > > */ > > > > schedule_work(&pca955x->work); > > > > - > > - spin_unlock(&pca955x->lock); > > > > } > > > > static int __devinit pca955x_probe(struct i2c_client *client, > > > > const struct i2c_device_id *id) > > > > { > > > > - struct pca955x_led *pca955x; > > + struct pca955x *pca955x; > > + struct pca955x_led *pca955x_led; > > > > struct pca955x_chipdef *chip; > > struct i2c_adapter *adapter; > > struct led_platform_data *pdata; > > > > @@ -282,39 +293,48 @@ static int __devinit pca955x_probe(struct i2c_client > > *client, } > > > > } > > > > - pca955x = kzalloc(sizeof(*pca955x) * chip->bits, GFP_KERNEL); > > + pca955x = kzalloc(sizeof(*pca955x), GFP_KERNEL); > > > > if (!pca955x) > > > > return -ENOMEM; > > > > + pca955x->leds = kzalloc(sizeof(*pca955x_led) * chip->bits, GFP_KERNEL); > > + if (!pca955x->leds) { > > + err = -ENOMEM; > > + goto exit_nomem; > > + } > > + > > > > i2c_set_clientdata(client, pca955x); > > > > + mutex_init(&pca955x->lock); > > + pca955x->client = client; > > + pca955x->chipdef = chip; > > + > > > > for (i = 0; i < chip->bits; i++) { > > > > - pca955x[i].chipdef = chip; > > - pca955x[i].client = client; > > - pca955x[i].led_num = i; > > + pca955x_led = &pca955x->leds[i]; > > + pca955x_led->led_num = i; > > + pca955x_led->pca955x = pca955x; > > > > /* Platform data can specify LED names and default triggers */ > > if (pdata) { > > > > if (pdata->leds[i].name) > > > > - snprintf(pca955x[i].name, > > - sizeof(pca955x[i].name), "pca955x:%s", > > - pdata->leds[i].name); > > + snprintf(pca955x_led->name, > > + sizeof(pca955x_led->name), "pca955x:%s", > > + pdata->leds[i].name); > > > > if (pdata->leds[i].default_trigger) > > > > - pca955x[i].led_cdev.default_trigger = > > + pca955x_led->led_cdev.default_trigger = > > > > pdata->leds[i].default_trigger; > > > > } else { > > > > - snprintf(pca955x[i].name, sizeof(pca955x[i].name), > > + snprintf(pca955x_led->name, sizeof(pca955x_led->name), > > > > "pca955x:%d", i); > > > > } > > > > - spin_lock_init(&pca955x[i].lock); > > - > > - pca955x[i].led_cdev.name = pca955x[i].name; > > - pca955x[i].led_cdev.brightness_set = pca955x_led_set; > > + pca955x_led->led_cdev.name = pca955x_led->name; > > + pca955x_led->led_cdev.brightness_set = pca955x_led_set; > > > > - INIT_WORK(&pca955x[i].work, pca955x_led_work); > > + INIT_WORK(&pca955x_led->work, pca955x_led_work); > > > > - err = led_classdev_register(&client->dev, &pca955x[i].led_cdev); > > + err = led_classdev_register(&client->dev, > > + &pca955x_led->led_cdev); > > > > if (err < 0) > > > > goto exit; > > > > } > > > > @@ -337,10 +357,12 @@ static int __devinit pca955x_probe(struct i2c_client > > *client, > > > > exit: > > while (i--) { > > > > - led_classdev_unregister(&pca955x[i].led_cdev); > > - cancel_work_sync(&pca955x[i].work); > > + led_classdev_unregister(&pca955x->leds[i].led_cdev); > > + cancel_work_sync(&pca955x->leds[i].work); > > > > } > > > > + kfree(pca955x->leds); > > > > +exit_nomem: > > kfree(pca955x); > > > > return err; > > > > @@ -348,14 +370,15 @@ exit: > > static int __devexit pca955x_remove(struct i2c_client *client) > > { > > > > - struct pca955x_led *pca955x = i2c_get_clientdata(client); > > + struct pca955x *pca955x = i2c_get_clientdata(client); > > > > int i; > > > > for (i = 0; i < pca955x->chipdef->bits; i++) { > > > > - led_classdev_unregister(&pca955x[i].led_cdev); > > - cancel_work_sync(&pca955x[i].work); > > + led_classdev_unregister(&pca955x->leds[i].led_cdev); > > + cancel_work_sync(&pca955x->leds[i].work); > > > > } > > > > + kfree(pca955x->leds); > > > > kfree(pca955x); > > > > return 0; -- Dipl.-Inf. Alexander Stein SYS TEC electronic GmbH August-Bebel-Str. 29 D-07973 Greiz Tel: +49-3661-6279-0, Fax: +49-3661-6279-99 eMail: Alexander.Stein@systec-electronic.com Internet: http://www.systec-electronic.com Managing Director: Dipl.-Phys. Siegmar Schmidt Commercial registry: Amtsgericht Jena, HRB 205563 -- 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/