[PATCH v2 1/4] dt-bindings: i2c: aspeed: add buffer and DMA mode transfer support

Jae Hyun Yoo jae.hyun.yoo at linux.intel.com
Wed Feb 10 06:17:29 AEDT 2021

On 2/9/2021 4:10 AM, Joel Stanley wrote:
> On Wed, 3 Feb 2021 at 23:03, Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com> wrote:
>> Hi Joel
>> On 1/28/2021 11:36 AM, Jae Hyun Yoo wrote:
>>> Hi Joel
>>> On 1/27/2021 4:06 PM, Joel Stanley wrote:
>>>>>> All this information doesn't need to be in the binding.
>>>>>> It's also an oddly structured dts file if this is what you are doing...
>>>>> I removed the default buffer mode settings that I added into
>>>>> 'aspeed-g4.dtsi' and 'aspeed-g5.dtsi' in v1 to avoid touching of the
>>>>> default transfer mode setting, but each bus should use its dedicated
>>>>> SRAM buffer range for enabling buffer mode so I added this information
>>>>> at here as overriding examples instead. I thought that binding document
>>>>> is a right place for providing this information but looks like it's not.
>>>>> Any recommended place for it? Is it good enough if I add it just into
>>>>> the commit message?
>>>> I agree with Rob, we don't need this described in the device tree
>>>> (binding or dts). We know what the layout is for a given aspeed
>>>> family, so the driver can have this information hard coded.
>>>> (Correct me if I've misinterpted here Rob)
>>> Makes sense. Will add these settings into the driver module as hard
>>> coded per each bus.
>> Realized that the SRAM buffer range setting should be added into device
>> tree because each bus module should get the dedicated IO resource range.
>> So I'm going to add it to dtsi default reg setting for each I2C bus
>> and will remove this description in binding. Also, I'll add a mode
>> setting property instead to keep the current setting as byte mode.
> I don't understand. What do you propose adding?

I'm going to add reg resource for the SRAM buffer per each bus like

reg = <0x40 0x40>, <0x800 0x80>;

into the aspeed-g*.dtsi but adding like this will not be a key for
enabling buffer mode like this v2 does. Also, I'm going to remove the
'aspeed,dma-buf-size' in this patch series and I'll add fixed DMA length
as a configuration per each SoC. Instead, I'm going to add a xfer mode
property e.g. 'aspeed,i2c-xfer-mode' to select 'byte', 'buffer' or 'dma'


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