Re: [PATCH v3 1/1] i2c: qcom-geni: Provide an option to disable DMA processing

[Peter Rosin]

On 2019-09-05 15:49, Wolfram Sang wrote:
> Hi Lee,
> 
> I understand you are in a hurry, but please double check before
> sending...

Linus indicated that an rc8 is coming up, which should provide an extra week.
https://lwn.net/Articles/798152/

> On Thu, Sep 05, 2019 at 11:22:47AM +0100, Lee Jones wrote:
>> We have a production-level laptop (Lenovo Yoga C630) which is exhibiting
>> a rather horrific bug.  When I2C HID devices are being scanned for at
>> boot-time the QCom Geni based I2C (Serial Engine) attempts to use DMA.
>> When it does, the laptop reboots and the user never sees the OS.
>>
>> The beautiful thing about this approach is that, *if* the Geni SE DMA
>> ever starts working, we can remove the C code and any old properties
>> left in older DTs just become NOOP.  Older kernels with newer DTs (less
>> of a priority) *still* will not work - but they do not work now anyway.
> 
> ... becasue this paragraph doesn't fit anymore. Needs to be reworded.
> 
>>
>> Fixes: 8bc529b25354 ("soc: qcom: geni: Add support for ACPI")
> 
> As said in the other thread, I don't get it, but this is not a show
> stopper for me.

WAG: because ACPI made some driver load at all, and when it
did it something started happening which crashed some machines.

Cheers,
Peter