> On Jul 28, 2020, at 4:16 AM, Wolfram Sang <wsa@xxxxxxxxxx> wrote:
>
>
>> * Allocated bit 4 (I2C_SMBUS3_BLOCK=0x10), to simplify Smbus2
>> compatibility: I2C_SMBUS_*BLOCK* = (<old type>|0x10)
>
> I think the code becomes easier to understand, if we use new transfer
> types a bit more explicitly. Also, I am not sure of the extra bit
> because it is not clearly visible that types >= 16 and <= 31 will have a
> special meaning. We could do like this if we sacrifice one number for
> an unused BROKEN with 255 byte:
>
> -#define I2C_SMBUS_BLOCK_DATA 5
> +#define I2C_SMBUS2_BLOCK_DATA 5 /* 32 byte only, deprecated */
> -#define I2C_SMBUS_I2C_BLOCK_BROKEN 6
> +#define I2C_SMBUS2_I2C_BLOCK_BROKEN 6 /* 32 byte only, deprecated */
> -#define I2C_SMBUS_BLOCK_PROC_CALL 7 /* SMBus 2.0 */
> +#define I2C_SMBUS2_BLOCK_PROC_CALL 7 /* SMBus 2.0, 32 byte only, deprecated */
> -#define I2C_SMBUS_I2C_BLOCK_DATA 8
> +#define I2C_SMBUS2_I2C_BLOCK_DATA 8 /* 32 byte only, deprecated */
>
> +#define I2C_SMBUS_BLOCK_DATA 9
> +#define I2C_SMBUS_I2C_BLOCK_BROKEN 10 /* FIXME: probably say "don't use" here
> +#define I2C_SMBUS_BLOCK_PROC_CALL 11 /* SMBus >= 2.0 */
> +#define I2C_SMBUS_I2C_BLOCK_DATA 12
>>
>
>> + user_len = kmalloc_array(nmsgs, sizeof(*user_len), GFP_KERNEL);
>> + if (!user_len) {
>> + res = -ENOMEM;
>> + goto out;
>> + }
>
> Maybe on stack? I2C_RDWR_IOCTL_MAX_MSGS will ensure this will stay at a
> sane value.
>
>> @@ -313,7 +357,19 @@ static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
>> union i2c_smbus_data __user *data)
>> {
>> union i2c_smbus_data temp = {};
>> - int datasize, res;
>> + int block_max, datasize, res;
>> +
>
> 'size' is really a misleading name :(
Yep. :/
> + if (size <= I2C_SMBUS2_I2C_BLOCK_DATA) {
> + if (size >= I2C_SMBUS2_BLOCK_DATA)
> + size += I2C_SMBUS_BLOCK_DATA - I2C_SMBUS2_BLOCK_DATA;
> + block_max = I2C_SMBUS_BLOCK_MAX;
> + } else {
> + block_max = I2C_SMBUS3_BLOCK_MAX;
> + }
>
> Would this work, too?
“3” ;)
But I get what you mean.
I’m not too passionate about the bit flip. Adding relative offsets would work for me too.
In fact, if we just want to keep a full switch (size) {} and map {9, 10, 11} to {5, 7, 8},
(i.e. no dummy-broken), my world wouldn’t collapse yet.
Daniel
