RE: [PATCH v12 3/6] CPM/QE: use genalloc to manage CPM/QE muram

[Zhao Qiang]

On Sat, 2015-10-24 at 04:59 AM, Wood Scott-B07421 <scottwood@xxxxxxxxxxxxx> wrote:
> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Saturday, October 24, 2015 4:59 AM
> To: Zhao Qiang-B45475 <qiang.zhao@xxxxxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx;
> lauraa@xxxxxxxxxxxxxx; Xie Xiaobo-R63061 <X.Xie@xxxxxxxxxxxxx>;
> benh@xxxxxxxxxxxxxxxxxxx; Li Yang-Leo-R58472 <LeoLi@xxxxxxxxxxxxx>;
> paulus@xxxxxxxxx
> Subject: Re: [PATCH v12 3/6] CPM/QE: use genalloc to manage CPM/QE muram
> 
> Don't send HTML e-mail.
> 
> On Fri, 2015-10-23 at 02:06 -0500, Zhao Qiang-B45475 wrote:
> > On Fri, 2015-10-23 at 11:00 AM, Wood Scott-B07421
> > <scottwood@xxxxxxxxxxxxx>
> > wrote:
> > > -----Original Message-----
> > > From: Wood Scott-B07421
> > > Sent: Friday, October 23, 2015 11:00 AM
> > > To: Zhao Qiang-B45475 <qiang.zhao@xxxxxxxxxxxxx>
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx;
> > > lauraa@xxxxxxxxxxxxxx; Xie Xiaobo-R63061 <X.Xie@xxxxxxxxxxxxx>;
> > > benh@xxxxxxxxxxxxxxxxxxx; Li Yang-Leo-R58472 <LeoLi@xxxxxxxxxxxxx>;
> > > paulus@xxxxxxxxx
> > > Subject: Re: [PATCH v12 3/6] CPM/QE: use genalloc to manage CPM/QE
> > > muram
> > >
> > > On Wed, 2015-10-14 at 15:16 +0800, Zhao Qiang wrote:
> > > > -/**
> > > > +/*
> > > >   * cpm_muram_alloc - allocate the requested size worth of
> > > > multi-user
> > ram
> > > >   * @size: number of bytes to allocate
> > > >   * @align: requested alignment, in bytes @@ -141,59 +151,102 @@ out:
> > > >   */
> > > >  unsigned long cpm_muram_alloc(unsigned long size, unsigned long
> > > > align)  {
> > > > -     unsigned long start;
> > > >       unsigned long flags;
> > > > -
> > > > +     unsigned long start;
> > > > +     static struct genpool_data_align muram_pool_data;
> > > >       spin_lock_irqsave(&cpm_muram_lock, flags);
> > > > -     cpm_muram_info.alignment = align;
> > > > -     start = rh_alloc(&cpm_muram_info, size, "commproc");
> > > > -     memset(cpm_muram_addr(start), 0, size);
> > > > +     muram_pool_data.align = align;
> > > > +     gen_pool_set_algo(muram_pool, gen_pool_first_fit_align,
> > > > +                       &muram_pool_data);
> > > > +     start = cpm_muram_alloc_common(size, &muram_pool_data);
> > > >       spin_unlock_irqrestore(&cpm_muram_lock, flags);
> > > > -
> > > >       return start;
> > > >  }
> > > >  EXPORT_SYMBOL(cpm_muram_alloc);
> > >
> > > Why is muram_pool_data static?  Why is it being passed to
> > > gen_pool_set_algo()?
> > Cpm_muram use both align algo and fixed algo, so we need to set
> > corresponding algo and Algo data.
> 
> The data gets passed in via gen_pool_alloc_data().  The point was to allow it to
> be on the caller's stack, not a long-lived data structure shared by all callers and
> needing synchronization.

You mean it is not necessary to point pool->data to data, just passing the data to gen_pool_alloc_data()?
However, the algo it needed to be set.

> 
> > >The whole reason we're adding gen_pool_alloc_data()  is to avoid
> > >that.  Do we need gen_pool_alloc_algo() too?
> >
> > We add gen_pool_alloc_data() to pass data to algo, because align algo
> > and fixed algo, Because align and fixed algos need specific data.
> 
> And my point is that because of that, it seems like we need a version that
> accepts an algorithm as well.

It the user just use only one algo, it doesnât need to set algo, 
However, qe_muram use two algos with alloc_align function
And alloc_fixed function.

-Zhao