Re: [PATCH 2/2] spi: qcom-geni: Add property to force GSI mode

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 6/15/26 6:25 AM, Pengyu Luo wrote:
> On Mon, Jun 15, 2026 at 5:18 AM Dmitry Baryshkov
> <dmitry.baryshkov@oss.qualcomm.com> wrote:
>>
>> On Sun, Jun 14, 2026 at 04:34:24PM +0800, Pengyu Luo wrote:
>>> Some devices (such as gaokun3) do not disable FIFO mode, causing the
>>> driver to fallback to FIFO mode by default. However, these platforms
>>> also support GSI mode, which is highly preferred for certain
>>> peripherals like SPI touchscreens to improve performance.
>>>
>>> Introduce the "qcom,force-gsi-mode" device property to hint and force
>>> the controller into GSI mode during initialization.
>>
>> Ideally, this should be decided by the SPI controller based on the
>> requirements. Another option would be to prefer GSI for all transfers if
>> it is available, ignoring the FIFO even if it is not disabled.
>>
> 
> I have read reviews. Can we check if the compatible
> "qcom,sm6350-gpi-dma" is in DT? If the gpi dma controller is
> presented, then we enable GSI mode.


This hunk is very odd:

/*
 * in case of failure to get gpi dma channel, we can still do the
 * FIFO mode, so fallthrough
 */
dev_warn(mas->dev, "FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode\n");

In my understanding, GSI DMA mode is always preferable. +Mukesh, do
you have any insights?

Konrad