More updates to the I2C stack's fault reporting:  make the core stop
returning "-1" (usually "-EPERM") for all faults.  Instead, pass lower
level fault code up the stack, or return some appropriate errno.

This patch happens to touch almost exclusively SMBus calls.

Signed-off-by: David Brownell <[EMAIL PROTECTED]>
---
Combine this and the previous i2c_adapter patch, and I suspect that
well over half the causes of bogus "-EPERM" reports are now gone ...
including in particular those reported by i2c-dev to userspace when
it issues SMBus calls "for portability".

 drivers/i2c/i2c-core.c |   76 +++++++++++++++++++++++++++----------------------
 1 file changed, 43 insertions(+), 33 deletions(-)

--- g26.orig/drivers/i2c/i2c-core.c     2008-05-03 12:57:16.000000000 -0700
+++ g26/drivers/i2c/i2c-core.c  2008-05-03 12:58:10.000000000 -0700
@@ -1113,7 +1113,7 @@ int i2c_probe(struct i2c_adapter *adapte
 
                dev_warn(&adapter->dev, "SMBus Quick command not supported, "
                         "can't probe for chips\n");
-               return -1;
+               return -EOPNOTSUPP;
        }
 
        /* Probe entries are done second, and are not affected by ignore
@@ -1305,7 +1305,7 @@ static int i2c_smbus_check_pec(u8 cpec, 
        if (rpec != cpec) {
                pr_debug("i2c-core: Bad PEC 0x%02x vs. 0x%02x\n",
                        rpec, cpec);
-               return -1;
+               return -EPROTO;
        }
        return 0;
 }
@@ -1320,11 +1320,12 @@ EXPORT_SYMBOL(i2c_smbus_write_quick);
 s32 i2c_smbus_read_byte(struct i2c_client *client)
 {
        union i2c_smbus_data data;
-       if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
-                          I2C_SMBUS_READ,0,I2C_SMBUS_BYTE, &data))
-               return -1;
-       else
-               return data.byte;
+       int status;
+
+       status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                       I2C_SMBUS_READ, 0,
+                       I2C_SMBUS_BYTE, &data);
+       return (status < 0) ? status : data.byte;
 }
 EXPORT_SYMBOL(i2c_smbus_read_byte);
 
@@ -1338,11 +1339,12 @@ EXPORT_SYMBOL(i2c_smbus_write_byte);
 s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
 {
        union i2c_smbus_data data;
-       if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
-                          I2C_SMBUS_READ,command, I2C_SMBUS_BYTE_DATA,&data))
-               return -1;
-       else
-               return data.byte;
+       int status;
+
+       status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                       I2C_SMBUS_READ, command,
+                       I2C_SMBUS_BYTE_DATA, &data);
+       return (status < 0) ? status : data.byte;
 }
 EXPORT_SYMBOL(i2c_smbus_read_byte_data);
 
@@ -1359,11 +1361,12 @@ EXPORT_SYMBOL(i2c_smbus_write_byte_data)
 s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
 {
        union i2c_smbus_data data;
-       if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
-                          I2C_SMBUS_READ,command, I2C_SMBUS_WORD_DATA, &data))
-               return -1;
-       else
-               return data.word;
+       int status;
+
+       status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                       I2C_SMBUS_READ, command,
+                       I2C_SMBUS_WORD_DATA,  &data);
+       return (status < 0) ? status : data.word;
 }
 EXPORT_SYMBOL(i2c_smbus_read_word_data);
 
@@ -1397,11 +1400,13 @@ s32 i2c_smbus_read_block_data(struct i2c
                              u8 *values)
 {
        union i2c_smbus_data data;
+       int status;
 
-       if (i2c_smbus_xfer(client->adapter, client->addr, client->flags,
-                          I2C_SMBUS_READ, command,
-                          I2C_SMBUS_BLOCK_DATA, &data))
-               return -1;
+       status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                       I2C_SMBUS_READ, command,
+                       I2C_SMBUS_BLOCK_DATA, &data);
+       if (status)
+               return status;
 
        memcpy(values, &data.block[1], data.block[0]);
        return data.block[0];
@@ -1428,14 +1433,16 @@ s32 i2c_smbus_read_i2c_block_data(struct
                                  u8 length, u8 *values)
 {
        union i2c_smbus_data data;
+       int status;
 
        if (length > I2C_SMBUS_BLOCK_MAX)
                length = I2C_SMBUS_BLOCK_MAX;
        data.block[0] = length;
-       if (i2c_smbus_xfer(client->adapter,client->addr,client->flags,
-                             I2C_SMBUS_READ,command,
-                             I2C_SMBUS_I2C_BLOCK_DATA,&data))
-               return -1;
+       status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
+                       I2C_SMBUS_READ, command,
+                       I2C_SMBUS_I2C_BLOCK_DATA, &data);
+       if (status < 0)
+               return status;
 
        memcpy(values, &data.block[1], data.block[0]);
        return data.block[0];
@@ -1476,6 +1483,7 @@ static s32 i2c_smbus_xfer_emulated(struc
                                };
        int i;
        u8 partial_pec = 0;
+       int status;
 
        msgbuf0[0] = command;
        switch(size) {
@@ -1528,7 +1536,7 @@ static s32 i2c_smbus_xfer_emulated(struc
                                dev_err(&adapter->dev, "smbus_access called 
with "
                                       "invalid block write size (%d)\n",
                                       data->block[0]);
-                               return -1;
+                               return -EMSGSIZE;
                        }
                        for (i = 1; i < msg[0].len; i++)
                                msgbuf0[i] = data->block[i-1];
@@ -1541,7 +1549,7 @@ static s32 i2c_smbus_xfer_emulated(struc
                        dev_err(&adapter->dev, "%s called with invalid "
                                "block proc call size (%d)\n", __func__,
                                data->block[0]);
-                       return -1;
+                       return -EMSGSIZE;
                }
                msg[0].len = data->block[0] + 2;
                for (i = 1; i < msg[0].len; i++)
@@ -1559,7 +1567,7 @@ static s32 i2c_smbus_xfer_emulated(struc
                                dev_err(&adapter->dev, "i2c_smbus_xfer_emulated 
called with "
                                       "invalid block write size (%d)\n",
                                       data->block[0]);
-                               return -1;
+                               return -EMSGSIZE;
                        }
                        for (i = 1; i <= data->block[0]; i++)
                                msgbuf0[i] = data->block[i];
@@ -1568,7 +1576,7 @@ static s32 i2c_smbus_xfer_emulated(struc
        default:
                dev_err(&adapter->dev, "smbus_access called with invalid size 
(%d)\n",
                       size);
-               return -1;
+               return -EOPNOTSUPP;
        }
 
        i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
@@ -1586,13 +1594,15 @@ static s32 i2c_smbus_xfer_emulated(struc
                        msg[num-1].len++;
        }
 
-       if (i2c_transfer(adapter, msg, num) < 0)
-               return -1;
+       status = i2c_transfer(adapter, msg, num);
+       if (status < 0)
+               return status;
 
        /* Check PEC if last message is a read */
        if (i && (msg[num-1].flags & I2C_M_RD)) {
-               if (i2c_smbus_check_pec(partial_pec, &msg[num-1]) < 0)
-                       return -1;
+               status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
+               if (status < 0)
+                       return status;
        }
 
        if (read_write == I2C_SMBUS_READ)

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