[U-Boot] [PATCH v2 0/7] Align U-Boot I2C DM bus ID handling with Linux

[Michal Simek]

Hi Simon,

On 02. 02. 19 15:10, Simon Glass wrote:
> Hi Michal,
> 
> On Thu, 31 Jan 2019 at 08:31, Michal Simek <michal.simek at xilinx.com> wrote:
>>
>> U-Boot with I2C_DM enabled is not capable to list i2c busses connected
>> to i2c mux. For getting this work there is a need to find out highest
>> alias ID and use this uniq number for new buses connected to I2C mux.
>> This series is making this happen.
>>
>> There is only one missing piece which is that also i2c controllers which
>> are not listed in DT are not using this feature.
>>
>> Removing setting up aliases from i2c mux code and unifying it in the
>> same code ensures that numbering schema is proper if no alias is
>> specified.
>>
>> ZynqMP> i2c bus
>> Bus 0:  i2c at ff020000
>>    20: gpio at 20, offset len 1, flags 0
>>    21: gpio at 21, offset len 1, flags 0
>>    75: i2c-mux at 75, offset len 1, flags 0
>> Bus 1:  i2c at ff020000->i2c-mux at 75->i2c at 0
>> Bus 2:  i2c at ff020000->i2c-mux at 75->i2c at 1
>> Bus 3:  i2c at ff020000->i2c-mux at 75->i2c at 2
>> Bus 4:  i2c at ff030000  (active 4)
>>    74: i2c-mux at 74, offset len 1, flags 0
>>    75: i2c-mux at 75, offset len 1, flags 0
>> Bus 5:  i2c at ff030000->i2c-mux at 74->i2c at 0  (active 5)
>>    54: eeprom at 54, offset len 1, flags 0
>> Bus 6:  i2c at ff030000->i2c-mux at 74->i2c at 1
>> Bus 7:  i2c at ff030000->i2c-mux at 74->i2c at 2
>> Bus 8:  i2c at ff030000->i2c-mux at 74->i2c at 3
>> Bus 9:  i2c at ff030000->i2c-mux at 74->i2c at 4
>> Bus 10: i2c at ff030000->i2c-mux at 75->i2c at 0
>> Bus 11: i2c at ff030000->i2c-mux at 75->i2c at 1
>> Bus 12: i2c at ff030000->i2c-mux at 75->i2c at 2
>> Bus 13: i2c at ff030000->i2c-mux at 75->i2c at 3
>> Bus 14: i2c at ff030000->i2c-mux at 75->i2c at 4
>> Bus 15: i2c at ff030000->i2c-mux at 75->i2c at 5
>> Bus 16: i2c at ff030000->i2c-mux at 75->i2c at 6
>> Bus 17: i2c at ff030000->i2c-mux at 75->i2c at 7
>>
>> Thanks,
>> Michal
>>
>> Changes in v2:
>> - Update kernel-doc binding
>> - Return -1 in case of error. -1 means that the next free alias is 0.
>> - New patch
>> - New patch
>> - Use dev_read_alias_highest_id()
>> - Use uclass private data
>> - Use private uclass data
>> - Fix headers
>> - Change patch description to focus only on bus name
> 
> I don't have strong objections to this series, but I'd still like to
> try a bit harder on the existing req_seq/seq stuff.
> 
> I don't think we necessarily need to set the 'seq' before probe,
> although I suppose we could.
>
> But is there anything to stop us moving some of the logic which sets
> seq to setting req_seq? We could check the aliases and then set
> req_seq during bind(), perhaps?

Let me put this to my TODO list. But it is not a task which you know
will be done in some hours. It requires to study the whole logic if this
works for all cases.

> This would be better for code size since it would help all subsystems.

This approach is used in the linux kernel that's why there is no way to
get rid of dev_read_alias_highest_id() as function.
It means only i2c_uclass_init() and little code in i2c_post_bind() could
be removed. That's why I don't think we will improve size a lot.
If this is copied to other subsystems then yes it will be more useful.
If we have just one now we can't save a lot.

Heiko: Can you please take a look at this series? I have another 7
patches on the top of this series which depends on it which cleanup all
zynq/zynqmp platforms and I would like to close this to be able to move.

Thanks,
Michal