[PATCH 2/4] [media] em28xx: reduce stack usage in probe functions
From: Arnd Bergmann
Date: Thu Feb 02 2017 - 09:53:54 EST
The two i2c probe functions use a lot of stack since they put
an i2c_client structure in a local variable:
drivers/media/usb/em28xx/em28xx-camera.c: In function 'em28xx_probe_sensor_micron':
drivers/media/usb/em28xx/em28xx-camera.c:205:1: error: the frame size of 1256 bytes is larger than 1152 bytes [-Werror=frame-larger-than=]
drivers/media/usb/em28xx/em28xx-camera.c: In function 'em28xx_probe_sensor_omnivision':
drivers/media/usb/em28xx/em28xx-camera.c:317:1: error: the frame size of 1248 bytes is larger than 1152 bytes [-Werror=frame-larger-than=]
This cleans up both of the above by removing the need for those
structures, calling the lower-level i2c function directly.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/media/usb/em28xx/em28xx-camera.c | 87 ++++++++++++++++++--------------
1 file changed, 50 insertions(+), 37 deletions(-)
diff --git a/drivers/media/usb/em28xx/em28xx-camera.c b/drivers/media/usb/em28xx/em28xx-camera.c
index 89c890ba7dd6..e64940f95a91 100644
--- a/drivers/media/usb/em28xx/em28xx-camera.c
+++ b/drivers/media/usb/em28xx/em28xx-camera.c
@@ -99,6 +99,25 @@ static int em28xx_initialize_mt9m001(struct em28xx *dev)
return 0;
}
+/* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */
+static int em28xx_i2c_read_chip_id(struct em28xx *dev, u16 addr, u8 reg, void *buf)
+{
+ struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
+ struct i2c_msg msg[2];
+
+ msg[0].addr = addr;
+ msg[0].flags = client->flags & I2C_M_TEN;
+ msg[0].len = 1;
+ msg[0].buf = ®
+ msg[1].addr = addr;
+ msg[1].flags = client->flags & I2C_M_TEN;
+ msg[1].flags |= I2C_M_RD;
+ msg[1].len = 2;
+ msg[1].buf = buf;
+
+ return i2c_transfer(client->adapter, msg, 2);
+}
+
/*
* Probes Micron sensors with 8 bit address and 16 bit register width
*/
@@ -106,48 +125,29 @@ static int em28xx_probe_sensor_micron(struct em28xx *dev)
{
int ret, i;
char *name;
- u8 reg;
__be16 id_be;
+ u16 addr;
u16 id;
- 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];
- /* NOTE: i2c_smbus_read_word_data() doesn't work with BE data */
+ addr = micron_sensor_addrs[i];
/* Read chip ID from register 0x00 */
- reg = 0x00;
- ret = i2c_master_send(&client, ®, 1);
+ ret = em28xx_i2c_read_chip_id(dev, addr, 0x00, &id_be);
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);
- continue;
- }
- 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);
+ addr << 1, ret);
continue;
}
id = be16_to_cpu(id_be);
/* Read chip ID from register 0xff */
- reg = 0xff;
- ret = i2c_master_send(&client, ®, 1);
+ ret = em28xx_i2c_read_chip_id(dev, addr, 0xff, &id_be);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
- client.addr << 1, ret);
- continue;
- }
- 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);
+ addr << 1, ret);
continue;
}
/* Validate chip ID to be sure we have a Micron device */
@@ -197,13 +197,26 @@ 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;
+ dev->i2c_client[dev->def_i2c_bus].addr = addr;
return 0;
}
return -ENODEV;
}
+/* like i2c_smbus_read_byte_data, but allows passing an addr */
+static int em28xx_smbus_read_byte(struct em28xx *dev, u16 addr, u8 command)
+{
+ struct i2c_client *client = &dev->i2c_client[dev->def_i2c_bus];
+ union i2c_smbus_data data;
+ int status;
+
+ status = i2c_smbus_xfer(client->adapter, addr, client->flags,
+ I2C_SMBUS_READ, command,
+ I2C_SMBUS_BYTE_DATA, &data);
+ return (status < 0) ? status : data.byte;
+}
+
/*
* Probes Omnivision sensors with 8 bit address and register width
*/
@@ -212,31 +225,31 @@ static int em28xx_probe_sensor_omnivision(struct em28xx *dev)
int ret, i;
char *name;
u8 reg;
+ u16 addr;
u16 id;
- 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];
+ addr = omnivision_sensor_addrs[i];
/* Read manufacturer ID from registers 0x1c-0x1d (BE) */
reg = 0x1c;
- ret = i2c_smbus_read_byte_data(&client, reg);
+ ret = em28xx_smbus_read_byte(dev, addr, 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);
+ addr << 1, ret);
continue;
}
id = ret << 8;
reg = 0x1d;
- ret = i2c_smbus_read_byte_data(&client, reg);
+ ret = em28xx_smbus_read_byte(dev, addr, reg);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
- client.addr << 1, ret);
+ addr << 1, ret);
continue;
}
id += ret;
@@ -245,20 +258,20 @@ 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 = em28xx_smbus_read_byte(dev, addr, reg);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
- client.addr << 1, ret);
+ addr << 1, ret);
continue;
}
id = ret << 8;
reg = 0x0b;
- ret = i2c_smbus_read_byte_data(&client, reg);
+ ret = em28xx_smbus_read_byte(dev, addr, reg);
if (ret < 0) {
dev_err(&dev->intf->dev,
"couldn't read from i2c device 0x%02x: error %i\n",
- client.addr << 1, ret);
+ addr << 1, ret);
continue;
}
id += ret;
@@ -309,7 +322,7 @@ 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;
+ dev->i2c_client[dev->def_i2c_bus].addr = addr;
return 0;
}
--
2.9.0