Re: [PATCH v3 03/17] ufs: core: Introduce Multi-circular queue capability

[Asutosh Das]

On Thu, Oct 27 2022 at 14:10 -0700, Bart Van Assche wrote:
> On 10/20/22 11:03, Asutosh Das wrote:
> > +
> > +	/*
> > +	 * This capability allows the host controller driver to turn on/off
> > +	 * MCQ mode. MCQ mode may be used to increase performance.
> > +	 */
> > +	UFSHCD_CAP_MCQ_EN				= 1 << 12,
> >  };
>
> I prefer that the above flag would only be introduced after a need 
> appears to disable MCQ, e.g. discovery of a host controller that is 
> too broken to enable MCQ.
I think this flag is useful during chip bring-ups &/or debugs.
Considering that this is a fairly new hardware block even though the HC supports
MCQ there could be times to keep it disabled.

> Since UFSHCI 4.0 controllers must support UFSHCI 3.0, shouldn't users 
> have a way to disable MCQ, e.g. via a kernel module parameter?
I can add a kernel module parameter to disable MCQ.
I think adding it to host driver (e.g. ufs-qcom) would be good.
Please let me know if you have a better place in mind.

> Thanks,
>
> Bart.