Re: [PATCH] gpiolib: fix allocation of mixed dynamic/static GPIOs

[Andreas Kemnade]

On Thu, 27 Apr 2023 06:20:34 +0000
Christophe Leroy <christophe.leroy@xxxxxxxxxx> wrote:

> Le 27/04/2023 à 08:00, Andy Shevchenko a écrit :
> > On Thu, Apr 27, 2023 at 8:40 AM Christophe Leroy
> > <christophe.leroy@xxxxxxxxxx> wrote:  
> >>
> >>
> >>
> >> Le 27/04/2023 à 00:03, Andreas Kemnade a écrit :  
> >>> [Vous ne recevez pas souvent de courriers de andreas@xxxxxxxxxxxx. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
> >>>
> >>> If static allocation and dynamic allocation GPIOs are present,
> >>> dynamic allocation pollutes the numberspace for static allocation,
> >>> causing static allocation to fail.
> >>> Enfore dynamic allocation above GPIO_DYNAMIC_BASE.  
> >>
> >> Hum ....
> >>
> >> Commit 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS") was supposed
> >> to enforce dynamic allocation above GPIO_DYNAMIC_BASE already.
> >>
> >> Can you describe what is going wrong exactly with the above commit ?  
> > 
> > Above commit only works to the first dynamic allocation, if you need
> > more than one with static ones present it mistakenly will give you a
> > base _below_ DYNAMIC_BASE.  
> 
> Ah right, that needs to be fixed.
> 
> > 
> > However, this change is just PoC I proposed, the conditional and
> > action should be slightly different to cover a corner case, when
> > statically allocated chip overlaps the DYNAMIC_BASE, i.e. gdev->base <
> > DYNAMIC_BASE, while gdev->base + gdev->ngpio >= DYNAMIC_BASE.
> >   
> 
> Yes you are right, that's gdev->base + gdev->ngpio that should be checked.
> 
and that not with simple continue or base might simply stay at DYNAMIC_BASE.

I will send a v2 of this patch with refined logic.

Regards,
Andreas