Re: [PATCH v3 0/3] i2c: designware: Add TI TDA54 I2C support

[Aniket Limaye <a-limaye@ti.com>]

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On 25/09/26 15:11, Andy Shevchenko wrote:
> On Fri, Sep 25, 2026 at 12:26:27PM +0530, Aniket Limaye wrote:
>> Add new compatible and update driver to support Synopsys Advanced I2C
>> Controller (DWC_i2c [0]) present on TI TDA54 SoC. This is needed since
>> this controller differs from the existing designware i2c (DW_apb_i2c
>> [1]) in its register offsets and some register definitions.
>>
>> The new compatible updates driver logic due to changes in register
>> definitions:
>>
>> - The new register offsets are handled by first refactoring the driver
>>    to use a map of register IDs to their offsets.
>> - Similarly, also update the driver to use an updated CON-register
>>    bitfield definition.
>> - Interrupts are acknowledged by writing a bitmask to a single CLR_INTR
>>    register instead of reading N dedicated CLR_* registers;
>>    i2c_dw_ack_intr() picks the right method based on dev->flags.
>> - One HCNT/LCNT register pair is shared between standard and fast speed
>>    instead of having one pair each; i2c_dw_write_timings() writes
>>    whichever value set matches the configured speed.
>> - No COMP_PARAM_1 register, so FIFO depth and high-speed-mode support
>>    can't be autodetected: FIFO depth now comes from the required
>>    snps,tx-fifo-depth/snps,rx-fifo-depth DT properties, and the
>>    high-speed capability check is skipped.
>> - No defined CON.RESTART_EN bit; treat it as always set.
>> - TDA54 SoC does not support SMBus, so skip accesses to those registers.
>>
>> [0]: DWC_i2c_reference.pdf
>> [1]: DW_apb_i2c_databook.pdf
> Still doesn't look good. The current register layout may be left as is. What
> you need is translate it in the respective regmap callbacks in case we are
> enumerated on the different IP. Also possible to have a different regmap
> config for the different HW where you translate them only in one place.

Is it confusing to keep using existing offsets in regmap_read/write() 
call sites for TDA54, and let the regmap silently handle the translation?

Given that we do *not* have any new registers in use on the tda54 
version that were not there in the original one, I guess it works... 
will send a v4 as per your suggestion.

Thanks,
Aniket

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