Re: [Xen-devel] [PATCH v6 10/31] xen/arm: ITS: Introduce gic_is_lpi helper function

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi,

On 03/09/2015 07:32, Vijay Kilari wrote:
> On Tue, Sep 1, 2015 at 6:32 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> > On 01/09/15 12:56, Vijay Kilari wrote:
> > > > BTW, I suggested to create a field nr_lpis but you decided to store the
> > > > number of bits supported. Why?
> > > I have nr_lpis field in vgic structure (patch #17). But it just tells
> > > how LPIs are supported
> > > for a domain.
> > Why are you speaking about vgic structure? I'm only suggesting to
> > replace you nr_id_bits by nr_lpis in the hw GIC. AFAICT, there is
> > nothing to prevent having 2 field using the same name on 2 differents
> > structure...
> >
> > > Where as nr_id_bits shows total number of  lpis that hw supports.
> > No nr_id_bits shows the total number of interrupt not LPIs. The total
> > number of LPIs is (1 << nr_id_bits) - 8092. Although (1 << nr_id_bits)
> > gives you the last LPI interrupt ID supported.
> >
> > Anyway, as I said earlier, re-calculating the last LPI interrupt ID
> > everytime based on the shift is time consuming. You should optimize for
> > the common case rather than using copy the raw value (i.e ID bits) from
> > the HW directly.
> >
> > Maybe the name "max_lpi_id" would make more sense to you for a name?
> Instead of storing max_lpi_id which is ( 1 << nr_id_bits) - 8192, I prefer
> to rename nr_id_bits as nr_irq_ids which can be initialized to (1 << nr_id_bits)
> for gicv3 and gicv2_info.nr_lines for gicv2.
I'm fine with that.

Regards,

--
Julien Grall

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