Re: [PATCH] regulator: ab8500: Fix get_mode for shared mode regulators

[Bengt Jönsson]

On 04/15/2013 04:11 PM, Axel Lin wrote:
> 2013/4/15 Bengt Jönsson <bengt.g.jonsson@xxxxxxxxxxxxxx>:
> > On 04/15/2013 02:13 PM, Axel Lin wrote:
> > > > I guess what you don't like with the current approach is that the driver
> > > > returns REGULATOR_MODE_IDLE in some cases where the mode register is set
> > > > to
> > > > LP. But I think, with patch applied, the control may be wrong in some
> > > > cases
> > > > because the regulator framework will call get_mode and see that the mode
> > > > is
> > > > already correct and not call set_mode so lp_mode_req will not get
> > > > updated. I
> > > I got your point now.
> > >
> > > My point is get_mode() should always return "correct" status by
> > > reading register value.
> > > And as you mentioned, regulator_set_mode() did check current mode and
> > > won't call
> > > set_mode callback if current mode is the same as the target mode.
> > > And that is why this patch won't work.
> > >
> > > However, Make get_mode() return "incorrect" status to avoid above
> > > issue looks wrong to me.
> > >
> > > Regards,
> > > Axel
> > I understand your point of view, but I think that the framework (as it is
> > currently implemented) expects to get the requested mode of the regulator in
> > this case, not the actual mode (in the shared mode register).The alternative
> > could be to change the framework in some way.
> >
> > Any ideas? Otherwise I propose to keep the code and maybe add a comment.
> It looks to me a simple fix is to just get rid of the check of old mode with
> new mode setting.
>
> Something like reverse of commit 500b4ac90d1103
> "regulator: return set_mode is same mode is requested" would work.
>
> Regards,
> Axel
Reverting 500b4ac90d1103 makes sense, but first I want to mention two 
things:
1. In some cases it is not even possible to know the actual current 
state of a regulator because it is controlled by HW as well as SW. We 
have several examples of this.
2. regulator_enable/disable also checks the current status before 
setting the regulator. Should these checks be removed as well?

Regards,

Bengt

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/