On Tue, 30 Mar 2021 14:06:37 +0100,
Lorenzo Pieralisi <lorenzo.pieral...@arm.com> wrote:
>
> On Tue, Mar 30, 2021 at 12:05:46PM +0100, Lorenzo Pieralisi wrote:
> > On Tue, Mar 30, 2021 at 11:33:13AM +0100, Marc Zyngier wrote:
> > > [+Lorenzo, +Julien on an actual email address]
> > >
> > > On Tue, 30 Mar 2021 11:06:19 +0100,
> > > Lecopzer Chen <lecopzer.c...@mediatek.com> wrote:
> > > >
> > > > When pseudo-NMI enabled, register_nmi() set priority of specific IRQ
> > > > by byte ops, and this doesn't work in GIC-600.
> > > >
> > > > We have asked ARM Support [1]:
> > > > > Please refer to following description in
> > > > > "2.1.2 Distributor ACE-Lite slave interface" of GIC-600 TRM for
> > > > > the GIC600 ACE-lite slave interface supported sizes:
> > > > > "The GIC-600 only accepts single beat accesses of the sizes for
> > > > > each register that are shown in the Programmers model,
> > > > > see Chapter 4 Programmer's model on page 4-102.
> > > > > All other accesses are rejected and given either an
> > > > > OKAY or SLVERR response that is based on the GICT_ERR0CTLR.UE bit.".
> > > >
> > > > Thus the register needs to be written by double word operation and
> > > > the step will be: read 32bit, set byte and write it back.
> > > >
> > > > [1] https://services.arm.com/support/s/case/5003t00001L4Pba
> > >
> > > You do realise that this link:
> > >
> > > - is unusable for most people as it is behind a registration interface
> > > - discloses confidential information to other people
> > >
> > > I strongly suggest you stop posting such links.
> > >
> > > >
> > > > Signed-off-by: Lecopzer Chen <lecopzer.c...@mediatek.com>
> > > > ---
> > > > drivers/irqchip/irq-gic-v3.c | 13 ++++++++++++-
> > > > 1 file changed, 12 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> > > > index eb0ee356a629..cfc5a6ad30dc 100644
> > > > --- a/drivers/irqchip/irq-gic-v3.c
> > > > +++ b/drivers/irqchip/irq-gic-v3.c
> > > > @@ -440,10 +440,21 @@ static void gic_irq_set_prio(struct irq_data *d,
> > > > u8 prio)
> > > > {
> > > > void __iomem *base = gic_dist_base(d);
> > > > u32 offset, index;
> > > > + u32 val, prio_offset_mask, prio_offset_shift;
> > > >
> > > > offset = convert_offset_index(d, GICD_IPRIORITYR, &index);
> > > >
> > > > - writeb_relaxed(prio, base + offset + index);
> > > > + /*
> > > > + * GIC-600 memory mapping register doesn't support byte
> > > > opteration,
> > > > + * thus read 32-bits from register, set bytes and wtire back to
> > > > it.
> > > > + */
> > > > + prio_offset_shift = (index & 0x3) * 8;
> > > > + prio_offset_mask = GENMASK(prio_offset_shift + 7,
> > > > prio_offset_shift);
> > > > + index &= ~0x3;
> > > > + val = readl_relaxed(base + offset + index);
> > > > + val &= ~prio_offset_mask;
> > > > + val |= prio << prio_offset_shift;
> > > > + writel_relaxed(val, base + offset + index);
> > > > }
> > > >
> > > > static u32 gic_get_ppi_index(struct irq_data *d)
> > >
> > > From the architecture spec:
> > >
> > > <quote>
> > > 11.1.3 GIC memory-mapped register access
> > >
> > > In any system, access to the following registers must be supported:
> > >
> > > [...]
> > > * Byte accesses to:
> > > - GICD_IPRIORITYR<n>.
> > > - GICD_ITARGETSR<n>.
> > > - GICD_SPENDSGIR<n>.
> > > - GICD_CPENDSGIR<n>.
> > > - GICR_IPRIORITYR<n>.
> > > </quote>
> > >
> > > So if GIC600 doesn't follow this architectural requirement, this is a
> > > HW erratum, and I want an actual description of the HW issue together
> > > with an erratum number.
> > >
> > > Lorenzo, can you please investigate on your side?
> >
> > Sure - I will look into it and report back.
>
> Checked - I don't think this patch is needed so it should be dropped and
> a follow-up discussion can continue in the relevant/appropriate forum -
> if there is anything left to discuss.
Thanks for having had a look. This really smells like an integration
issue rather than an actual GIC bug.
Lecopzer, please check with your HW people and potentially ARM, as I
think you are looking at the wrong problem.
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
