On Jan 19, 2011, at 12:12 PM, Jarod Wilson wrote:
> On Jan 19, 2011, at 8:50 AM, Jean Delvare wrote:
>
>> Hi Andy,
>>
>> On Wed, 19 Jan 2011 08:38:02 -0500, Andy Walls wrote:
>>> As I understand it, the rules/guidelines for I2C probing are now
>>> something like this:
>>>
>>> 1. I2C device driver modules (ir-kbd-i2c, lirc_zilog, etc.) should not
>>> do hardware probes at all. They are to assume the bridge or platform
>>> drivers verified the I2C slave hardware's existence somehow.
>>>
>>> 2. Bridge drivers (pvrusb, hdpvr, cx18, ivtv, etc.) should not ask the
>>> I2C subsystem to probe hardware that it knows for sure exists, or knows
>>> for sure does not exist. Just add the I2C device or not.
>>>
>>> 3. Bridge drivers should generally ask the I2C subsystem to probe for
>>> hardware that _may_ exist.
>>>
>>> 4. If the default I2C subsystem hardware probe method doesn't work on a
>>> particular hardware unit, the bridge driver may perform its own hardware
>>> probe or provide a custom hardware probe method to the I2C subsystem.
>>> hdpvr and pvrusb2 currently do the former.
>>
>> Yes, that's exactly how things are supposed to work now. And hopefully
>> it makes sense and helps you all write cleaner code (that was the
>> intent at least.)
>
> One more i2c question...
>
> Am I correct in assuming that since the zilog is a single device, which
> can be accessed via two different addresses (0x70 for tx, 0x71 for rx),
> that i2c_new_device() just once with both addresses in i2c_board_info
> is correct, vs. calling i2c_new_device() once for each address?
>
> At least, I'm reasonably sure that was the key to making the hdpvr IR
> behave with lirc_zilog, and after lunch, I should know if that's also
> the case for pvrusb2 devices w/a zilog IR chip.
Actually, in looking at things closer and talking to Andy on irc, it
looks like this:
static struct i2c_board_info pvr2_xcvr_i2c_board_info = {
I2C_BOARD_INFO("ir_tx_z8f0811_haup", Z8F0811_IR_TX_I2C_ADDR),
I2C_BOARD_INFO("ir_rx_z8f0811_haup", Z8F0811_IR_RX_I2C_ADDR),
};
Expands to:
static struct i2c_board_info pvr2_xcvr_i2c_board_info = {
.type = "ir_tx_z8f0811_haup",
.addr = Z8F0811_IR_TX_I2C_ADDR,
.type = "ir_rx_z8f0811_haup",
.addr = Z8F0811_IR_RX_I2C_ADDR,
};
In which case, we're actually only registering 0x71 -- i2c_new_device()
certainly only appears to act on a single address, anyway.
--
Jarod Wilson
jarod@xxxxxxxxxxxx
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