[media] em28xx: reduce stack usage in sensor probing functions

It's no longer necessary to keep the i2c_client in the device struct
unmodified until a sensor is found, so reduce stack usage in
em28xx_probe_sensor_micron() and em28xx_probe_sensor_omnivision() by using
a pointer to the client instead of a local copy.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/usb/em28xx/em28xx-camera.c b/drivers/media/usb/em28xx/em28xx-camera.c
index 89c890ba7dd61f843ec1bcb037f27318b5197b93..7b4129ab1cf92b7c6841c31a6ede2c42a6e9eab3 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx-camera.c
+++ b/drivers/media/usb/em28xx/em28xx-camera.c
@@ -110,44 +110,44 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
        __be16 id_be;
        u16 id;
 
-       struct i2c_client client = dev->i2c_client[dev->def_i2c_bus];
+       struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
 
        dev->em28xx_sensor = EM28XX_NOSENSOR;
        for (i = 0; micron_sensor_addrs[i] != I2C_CLIENT_END; i++) {
-               client.addr = micron_sensor_addrs[i];
+               client->addr = micron_sensor_addrs[i];
                /* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */
                /* Read chip ID from register 0x00 */
                reg = 0x00;
-               ret = i2c_master_send(&client, &reg, 1);
+               ret = i2c_master_send(client, &reg, 1);
                if (ret < 0) {
                        if (ret != -ENXIO)
                                dev_err(&dev->intf->dev,
                                        "couldn't read from i2c device 0x%02x: error %i\n",
-                                      client.addr << 1, ret);
+                                      client->addr << 1, ret);
                        continue;
                }
-               ret = i2c_master_recv(&client, (u8 *)&id_be, 2);
+               ret = i2c_master_recv(client, (u8 *)&id_be, 2);
                if (ret < 0) {
                        dev_err(&dev->intf->dev,
                                "couldn't read from i2c device 0x%02x: error %i\n",
-                               client.addr << 1, ret);
+                               client->addr << 1, ret);
                        continue;
                }
                id = be16_to_cpu(id_be);
                /* Read chip ID from register 0xff */
                reg = 0xff;
-               ret = i2c_master_send(&client, &reg, 1);
+               ret = i2c_master_send(client, &reg, 1);
                if (ret < 0) {
                        dev_err(&dev->intf->dev,
                                "couldn't read from i2c device 0x%02x: error %i\n",
-                               client.addr << 1, ret);
+                               client->addr << 1, ret);
                        continue;
                }
-               ret = i2c_master_recv(&client, (u8 *)&id_be, 2);
+               ret = i2c_master_recv(client, (u8 *)&id_be, 2);
                if (ret < 0) {
                        dev_err(&dev->intf->dev,
                                "couldn't read from i2c device 0x%02x: error %i\n",
-                               client.addr << 1, ret);
+                               client->addr << 1, ret);
                        continue;
                }
                /* Validate chip ID to be sure we have a Micron device */
@@ -197,7 +197,6 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
                        dev_info(&dev->intf->dev,
                                 "sensor %s detected\n", name);
 
-               dev->i2c_client[dev->def_i2c_bus].addr = client.addr;
                return 0;
        }
 
@@ -213,30 +212,30 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev)
        char *name;
        u8 reg;
        u16 id;
-       struct i2c_client client = dev->i2c_client[dev->def_i2c_bus];
+       struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
 
        dev->em28xx_sensor = EM28XX_NOSENSOR;
        /* NOTE: these devices have the register auto incrementation disabled
         * by default, so we have to use single byte reads !              */
        for (i = 0; omnivision_sensor_addrs[i] != I2C_CLIENT_END; i++) {
-               client.addr = omnivision_sensor_addrs[i];
+               client->addr = omnivision_sensor_addrs[i];
                /* Read manufacturer ID from registers 0x1c-0x1d (BE) */
                reg = 0x1c;
-               ret = i2c_smbus_read_byte_data(&client, reg);
+               ret = i2c_smbus_read_byte_data(client, reg);
                if (ret < 0) {
                        if (ret != -ENXIO)
                                dev_err(&dev->intf->dev,
                                        "couldn't read from i2c device 0x%02x: error %i\n",
-                                       client.addr << 1, ret);
+                                       client->addr << 1, ret);
                        continue;
                }
                id = ret << 8;
                reg = 0x1d;
-               ret = i2c_smbus_read_byte_data(&client, reg);
+               ret = i2c_smbus_read_byte_data(client, reg);
                if (ret < 0) {
                        dev_err(&dev->intf->dev,
                                "couldn't read from i2c device 0x%02x: error %i\n",
-                               client.addr << 1, ret);
+                               client->addr << 1, ret);
                        continue;
                }
                id += ret;
@@ -245,20 +244,20 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev)
                        continue;
                /* Read product ID from registers 0x0a-0x0b (BE) */
                reg = 0x0a;
-               ret = i2c_smbus_read_byte_data(&client, reg);
+               ret = i2c_smbus_read_byte_data(client, reg);
                if (ret < 0) {
                        dev_err(&dev->intf->dev,
                                "couldn't read from i2c device 0x%02x: error %i\n",
-                               client.addr << 1, ret);
+                               client->addr << 1, ret);
                        continue;
                }
                id = ret << 8;
                reg = 0x0b;
-               ret = i2c_smbus_read_byte_data(&client, reg);
+               ret = i2c_smbus_read_byte_data(client, reg);
                if (ret < 0) {
                        dev_err(&dev->intf->dev,
                                "couldn't read from i2c device 0x%02x: error %i\n",
-                               client.addr << 1, ret);
+                               client->addr << 1, ret);
                        continue;
                }
                id += ret;
@@ -309,7 +308,6 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev)
                        dev_info(&dev->intf->dev,
                                 "sensor %s detected\n", name);
 
-               dev->i2c_client[dev->def_i2c_bus].addr = client.addr;
                return 0;
        }