forked from Minki/linux
drivers/leds/leds-pca955x.c: fix race condition while setting brightness on several LEDs
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 betreen all LEDs. [akpm@linux-foundation.org: revert unintentional rename of pca955x_ledsel()] Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com> Cc: Richard Purdie <rpurdie@rpsys.net> Cc: Bryan Wu <bryan.wu@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -101,11 +101,16 @@ static const struct i2c_device_id pca955x_id[] = {
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};
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MODULE_DEVICE_TABLE(i2c, pca955x_id);
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struct pca955x_led {
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struct pca955x {
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struct mutex lock;
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struct pca955x_led *leds;
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struct pca955x_chipdef *chipdef;
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struct i2c_client *client;
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};
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struct pca955x_led {
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struct pca955x *pca955x;
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struct work_struct work;
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spinlock_t lock;
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enum led_brightness brightness;
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struct led_classdev led_cdev;
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int led_num; /* 0 .. 15 potentially */
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@ -140,7 +145,7 @@ static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
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*/
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static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
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{
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struct pca955x_led *pca955x = i2c_get_clientdata(client);
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struct pca955x *pca955x = i2c_get_clientdata(client);
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i2c_smbus_write_byte_data(client,
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pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
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@ -156,7 +161,7 @@ static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
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*/
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static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
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{
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struct pca955x_led *pca955x = i2c_get_clientdata(client);
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struct pca955x *pca955x = i2c_get_clientdata(client);
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i2c_smbus_write_byte_data(client,
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pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
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@ -169,7 +174,7 @@ static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
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*/
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static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
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{
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struct pca955x_led *pca955x = i2c_get_clientdata(client);
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struct pca955x *pca955x = i2c_get_clientdata(client);
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i2c_smbus_write_byte_data(client,
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pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
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@ -182,7 +187,7 @@ static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
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*/
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static u8 pca955x_read_ls(struct i2c_client *client, int n)
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{
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struct pca955x_led *pca955x = i2c_get_clientdata(client);
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struct pca955x *pca955x = i2c_get_clientdata(client);
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return (u8) i2c_smbus_read_byte_data(client,
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pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
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@ -190,18 +195,23 @@ static u8 pca955x_read_ls(struct i2c_client *client, int n)
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static void pca955x_led_work(struct work_struct *work)
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{
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struct pca955x_led *pca955x;
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struct pca955x_led *pca955x_led;
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struct pca955x *pca955x;
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u8 ls;
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int chip_ls; /* which LSx to use (0-3 potentially) */
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int ls_led; /* which set of bits within LSx to use (0-3) */
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pca955x = container_of(work, struct pca955x_led, work);
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chip_ls = pca955x->led_num / 4;
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ls_led = pca955x->led_num % 4;
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pca955x_led = container_of(work, struct pca955x_led, work);
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pca955x = pca955x_led->pca955x;
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chip_ls = pca955x_led->led_num / 4;
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ls_led = pca955x_led->led_num % 4;
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mutex_lock(&pca955x->lock);
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ls = pca955x_read_ls(pca955x->client, chip_ls);
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switch (pca955x->brightness) {
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switch (pca955x_led->brightness) {
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case LED_FULL:
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ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
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break;
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@ -219,12 +229,15 @@ static void pca955x_led_work(struct work_struct *work)
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* OFF, HALF, or FULL. But, this is probably better than
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* just turning off for all other values.
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*/
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pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness);
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pca955x_write_pwm(pca955x->client, 1,
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255 - pca955x_led->brightness);
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ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
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break;
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}
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pca955x_write_ls(pca955x->client, chip_ls, ls);
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mutex_unlock(&pca955x->lock);
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}
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static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
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@ -233,7 +246,6 @@ static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness v
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pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
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spin_lock(&pca955x->lock);
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pca955x->brightness = value;
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/*
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@ -241,14 +253,13 @@ static void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness v
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* can sleep.
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*/
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schedule_work(&pca955x->work);
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spin_unlock(&pca955x->lock);
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}
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static int __devinit pca955x_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct pca955x_led *pca955x;
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struct pca955x *pca955x;
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struct pca955x_led *pca955x_led;
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struct pca955x_chipdef *chip;
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struct i2c_adapter *adapter;
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struct led_platform_data *pdata;
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@ -282,39 +293,48 @@ static int __devinit pca955x_probe(struct i2c_client *client,
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}
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}
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pca955x = kzalloc(sizeof(*pca955x) * chip->bits, GFP_KERNEL);
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pca955x = kzalloc(sizeof(*pca955x), GFP_KERNEL);
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if (!pca955x)
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return -ENOMEM;
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pca955x->leds = kzalloc(sizeof(*pca955x_led) * chip->bits, GFP_KERNEL);
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if (!pca955x->leds) {
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err = -ENOMEM;
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goto exit_nomem;
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}
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i2c_set_clientdata(client, pca955x);
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mutex_init(&pca955x->lock);
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pca955x->client = client;
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pca955x->chipdef = chip;
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for (i = 0; i < chip->bits; i++) {
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pca955x[i].chipdef = chip;
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pca955x[i].client = client;
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pca955x[i].led_num = i;
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pca955x_led = &pca955x->leds[i];
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pca955x_led->led_num = i;
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pca955x_led->pca955x = pca955x;
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/* Platform data can specify LED names and default triggers */
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if (pdata) {
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if (pdata->leds[i].name)
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snprintf(pca955x[i].name,
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sizeof(pca955x[i].name), "pca955x:%s",
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pdata->leds[i].name);
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snprintf(pca955x_led->name,
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sizeof(pca955x_led->name), "pca955x:%s",
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pdata->leds[i].name);
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if (pdata->leds[i].default_trigger)
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pca955x[i].led_cdev.default_trigger =
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pca955x_led->led_cdev.default_trigger =
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pdata->leds[i].default_trigger;
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} else {
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snprintf(pca955x[i].name, sizeof(pca955x[i].name),
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snprintf(pca955x_led->name, sizeof(pca955x_led->name),
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"pca955x:%d", i);
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}
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spin_lock_init(&pca955x[i].lock);
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pca955x_led->led_cdev.name = pca955x_led->name;
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pca955x_led->led_cdev.brightness_set = pca955x_led_set;
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pca955x[i].led_cdev.name = pca955x[i].name;
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pca955x[i].led_cdev.brightness_set = pca955x_led_set;
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INIT_WORK(&pca955x_led->work, pca955x_led_work);
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INIT_WORK(&pca955x[i].work, pca955x_led_work);
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err = led_classdev_register(&client->dev, &pca955x[i].led_cdev);
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err = led_classdev_register(&client->dev,
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&pca955x_led->led_cdev);
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if (err < 0)
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goto exit;
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}
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@ -337,10 +357,12 @@ static int __devinit pca955x_probe(struct i2c_client *client,
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exit:
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while (i--) {
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led_classdev_unregister(&pca955x[i].led_cdev);
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cancel_work_sync(&pca955x[i].work);
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led_classdev_unregister(&pca955x->leds[i].led_cdev);
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cancel_work_sync(&pca955x->leds[i].work);
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}
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kfree(pca955x->leds);
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exit_nomem:
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kfree(pca955x);
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return err;
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@ -348,14 +370,15 @@ exit:
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static int __devexit pca955x_remove(struct i2c_client *client)
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{
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struct pca955x_led *pca955x = i2c_get_clientdata(client);
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struct pca955x *pca955x = i2c_get_clientdata(client);
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int i;
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for (i = 0; i < pca955x->chipdef->bits; i++) {
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led_classdev_unregister(&pca955x[i].led_cdev);
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cancel_work_sync(&pca955x[i].work);
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led_classdev_unregister(&pca955x->leds[i].led_cdev);
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cancel_work_sync(&pca955x->leds[i].work);
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}
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kfree(pca955x->leds);
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kfree(pca955x);
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return 0;
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