[media] saa7115: Don't use a dynamic array

At least on s390, gcc complains about that:
    drivers/media/i2c/saa7115.c: In function 'saa711x_detect_chip.constprop.2':
    drivers/media/i2c/saa7115.c:1647:1: warning: 'saa711x_detect_chip.constprop.2' uses dynamic stack allocation [enabled by default]

While for me the above report seems utterly bogus, as the
compiler should be optimizing saa711x_detect_chip, merging
it with saa711x_detect_chip and changing:
	char chip_ver[size - 1];
to
	char chip_ver[16];

because this function is only called on this code snippet:
	char name[17];
	...
	ident = saa711x_detect_chip(client, id, name, sizeof(name));

It seems that gcc is not optimizing it, at least on s390.

As getting rid of it is easy, let's do it.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/i2c/saa7115.c b/drivers/media/i2c/saa7115.c
index be32688..8316ae4 100644 (file)
--- a/drivers/media/i2c/saa7115.c
+++ b/drivers/media/i2c/saa7115.c
@@ -1602,6 +1602,8 @@ static const struct v4l2_subdev_ops saa711x_ops = {
        .vbi = &saa711x_vbi_ops,
 };
 
+#define CHIP_VER_SIZE  16
+
 /* ----------------------------------------------------------------------- */
 
 /**
@@ -1609,7 +1611,6 @@ static const struct v4l2_subdev_ops saa711x_ops = {
  * @client:            I2C client structure.
  * @id:                        I2C device ID structure.
  * @name:              Name of the device to be filled.
- * @size:              Size of the name var.
  *
  * Detects the Philips/NXP saa711x chip, or some clone of it.
  * if 'id' is NULL or id->driver_data is equal to 1, it auto-probes
@@ -1621,9 +1622,9 @@ static const struct v4l2_subdev_ops saa711x_ops = {
  */
 static int saa711x_detect_chip(struct i2c_client *client,
                               const struct i2c_device_id *id,
-                              char *name, unsigned size)
+                              char *name)
 {
-       char chip_ver[size - 1];
+       char chip_ver[CHIP_VER_SIZE];
        char chip_id;
        int i;
        int autodetect;
@@ -1631,7 +1632,7 @@ static int saa711x_detect_chip(struct i2c_client *client,
        autodetect = !id || id->driver_data == 1;
 
        /* Read the chip version register */
-       for (i = 0; i < size - 1; i++) {
+       for (i = 0; i < CHIP_VER_SIZE; i++) {
                i2c_smbus_write_byte_data(client, 0, i);
                chip_ver[i] = i2c_smbus_read_byte_data(client, 0);
                name[i] = (chip_ver[i] & 0x0f) + '0';
@@ -1643,7 +1644,7 @@ static int saa711x_detect_chip(struct i2c_client *client,
        /* Check if it is a Philips/NXP chip */
        if (!memcmp(name + 1, "f711", 4)) {
                chip_id = name[5];
-               snprintf(name, size, "saa711%c", chip_id);
+               snprintf(name, CHIP_VER_SIZE, "saa711%c", chip_id);
 
                if (!autodetect && strcmp(name, id->name))
                        return -EINVAL;
@@ -1651,7 +1652,7 @@ static int saa711x_detect_chip(struct i2c_client *client,
                switch (chip_id) {
                case '1':
                        if (chip_ver[0] & 0xf0) {
-                               snprintf(name, size, "saa711%ca", chip_id);
+                               snprintf(name, CHIP_VER_SIZE, "saa711%ca", chip_id);
                                v4l_info(client, "saa7111a variant found\n");
                                return V4L2_IDENT_SAA7111A;
                        }
@@ -1689,7 +1690,7 @@ static int saa711x_detect_chip(struct i2c_client *client,
                 * the lower nibble is a gm7113c.
                 */
 
-               strlcpy(name, "gm7113c", size);
+               strlcpy(name, "gm7113c", CHIP_VER_SIZE);
 
                if (!autodetect && strcmp(name, id->name))
                        return -EINVAL;
@@ -1714,13 +1715,13 @@ static int saa711x_probe(struct i2c_client *client,
        struct v4l2_subdev *sd;
        struct v4l2_ctrl_handler *hdl;
        int ident;
-       char name[17];
+       char name[CHIP_VER_SIZE + 1];
 
        /* Check if the adapter supports the needed features */
        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
                return -EIO;
 
-       ident = saa711x_detect_chip(client, id, name, sizeof(name));
+       ident = saa711x_detect_chip(client, id, name);
        if (ident == -EINVAL) {
                /* Chip exists, but doesn't match */
                v4l_warn(client, "found %s while %s was expected\n",