linux-kernel - Re: [PATCH 14/42] PCI: aardvark: Don't mask irq when mapping

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Date:   Fri, 7 May 2021 11:27:27 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Marek Behún <kabel@...nel.org>,
        Remi Pommarel <repk@...plefau.lt>, Xogium <contact@...ium.me>,
        Tomasz Maciej Nowak <tmn505@...il.com>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/42] PCI: aardvark: Don't mask irq when mapping

On Friday 07 May 2021 10:20:39 Marc Zyngier wrote:
> On Thu, 06 May 2021 16:31:25 +0100,
> Pali Rohár <pali@...nel.org> wrote:
> > 
> > By default, all Legacy INTx interrupts are masked, so there is no need to
> > mask this interrupt during irq_map callback.
> 
> What guarantees that they are actually masked? I would actually assume
> that the HW is in an unknown state at boot time.

Function advk_pcie_setup_hw() during driver probing mask all INTx interrupts:

    advk_writel(pcie, PCIE_ISR1_ALL_MASK, PCIE_ISR1_MASK_REG);

Individual INTx interrupts can be unmasked by PCIE_ISR1_INTX_ASSERT(val).
Macro PCIE_ISR1_ALL_MASK contains all bits from PCIE_ISR1_INTX_ASSERT(val).

> Thanks,
> 
> 	M.
> 
> > 
> > Signed-off-by: Pali Rohár <pali@...nel.org>
> > Reviewed-by: Marek Behún <kabel@...nel.org>
> > ---
> >  drivers/pci/controller/pci-aardvark.c | 1 -
> >  1 file changed, 1 deletion(-)
> > 
> > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> > index 2aced8c9ae9f..08f1157e1c5e 100644
> > --- a/drivers/pci/controller/pci-aardvark.c
> > +++ b/drivers/pci/controller/pci-aardvark.c
> > @@ -940,7 +940,6 @@ static int advk_pcie_irq_map(struct irq_domain *h,
> >  {
> >  	struct advk_pcie *pcie = h->host_data;
> >  
> > -	advk_pcie_irq_mask(irq_get_irq_data(virq));
> >  	irq_set_status_flags(virq, IRQ_LEVEL);
> >  	irq_set_chip_and_handler(virq, &pcie->irq_chip,
> >  				 handle_level_irq);
> > -- 
> > 2.20.1
> > 
> > 
> 
> -- 
> Without deviation from the norm, progress is not possible.