Re: [PATCH v3] i2c: tegra: Share same DMA channel for RX and TX

[Jon Hunter <jonathanh@nvidia.com>]

On 22/03/2023 12:00, Akhil R wrote:
>> On 22/03/2023 10:24, Akhil R wrote:
>>> Allocate only one DMA channel for I2C and share it for both TX and RX
>>> instead of using two different DMA hardware channels with the same
>>> slave ID. Since I2C supports only half duplex, there is no impact on
>>> perf with this.
>>>
>>> Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
>>
>> Just to confirm. This impacts all Tegra devices from Tegra20 to the
>> latest. Does this work for all Tegra and the different DMA controllers
>> that they have?
>>
> Yes, It should. I could see in the APB DMA driver that the same channel
> could be used for TX and RX and the direction is configured only during
> dma_prep_*() calls.
> I did not test it on a Tegra with APB DMA, but since it works very similar
> to GPC DMA there should not be any impact.


OK. BTW, this does not apply cleanly on top of -next. It appears that 
this is based on top "i2c: tegra: Fix PEC support for SMBUS block read" 
and that one needs to be applied first. This can be avoided if you send 
as a series.

Jon

-- 
nvpublic