linux-kernel - Re: [PATCH 18/42] PCI: aardvark: Correctly clear and unmask all MSI interrupts

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Message-ID: <20210507102136.2mlov44cywayzldt@pali>
Date:   Fri, 7 May 2021 12:21:36 +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 18/42] PCI: aardvark: Correctly clear and unmask all MSI
 interrupts

On Friday 07 May 2021 11:19:48 Marc Zyngier wrote:
> On Thu, 06 May 2021 16:31:29 +0100,
> Pali Rohár <pali@...nel.org> wrote:
> > 
> > Define a new macro PCIE_MSI_ALL_MASK and use it for masking, unmasking and
> > clearing all MSI interrupts.
> > 
> > Signed-off-by: Pali Rohár <pali@...nel.org>
> > Reviewed-by: Marek Behún <kabel@...nel.org>
> > Cc: stable@...r.kernel.org
> > ---
> >  drivers/pci/controller/pci-aardvark.c | 16 ++++++++++------
> >  1 file changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> > index 498810c00b6d..5e0243b2c473 100644
> > --- a/drivers/pci/controller/pci-aardvark.c
> > +++ b/drivers/pci/controller/pci-aardvark.c
> > @@ -117,6 +117,7 @@
> >  #define PCIE_MSI_ADDR_HIGH_REG			(CONTROL_BASE_ADDR + 0x54)
> >  #define PCIE_MSI_STATUS_REG			(CONTROL_BASE_ADDR + 0x58)
> >  #define PCIE_MSI_MASK_REG			(CONTROL_BASE_ADDR + 0x5C)
> > +#define     PCIE_MSI_ALL_MASK			GENMASK(31, 0)
> >  #define PCIE_MSI_PAYLOAD_REG			(CONTROL_BASE_ADDR + 0x9C)
> >  #define     PCIE_MSI_DATA_MASK			GENMASK(15, 0)
> >  
> > @@ -386,19 +387,22 @@ static void advk_pcie_setup_hw(struct advk_pcie *pcie)
> >  	advk_writel(pcie, reg, PCIE_CORE_CTRL2_REG);
> >  
> >  	/* Clear all interrupts */
> > +	advk_writel(pcie, PCIE_MSI_ALL_MASK, PCIE_MSI_STATUS_REG);
> >  	advk_writel(pcie, PCIE_ISR0_ALL_MASK, PCIE_ISR0_REG);
> >  	advk_writel(pcie, PCIE_ISR1_ALL_MASK, PCIE_ISR1_REG);
> >  	advk_writel(pcie, PCIE_IRQ_ALL_MASK, HOST_CTRL_INT_STATUS_REG);
> >  
> >  	/* Disable All ISR0/1 Sources */
> > -	reg = PCIE_ISR0_ALL_MASK;
> > -	reg &= ~PCIE_ISR0_MSI_INT_PENDING;
> > -	advk_writel(pcie, reg, PCIE_ISR0_MASK_REG);
> > -
> > +	advk_writel(pcie, PCIE_ISR0_ALL_MASK, PCIE_ISR0_MASK_REG);
> >  	advk_writel(pcie, PCIE_ISR1_ALL_MASK, PCIE_ISR1_MASK_REG);
> >  
> >  	/* Unmask all MSIs */
> > -	advk_writel(pcie, 0, PCIE_MSI_MASK_REG);
> > +	advk_writel(pcie, ~(u32)PCIE_MSI_ALL_MASK, PCIE_MSI_MASK_REG);
> 
> I really wonder why you'd unmask all MSIs. Yes, the current code does
> that already, but I'd expect MSIs to be individually unmasked as they
> get enabled by the core code.

Individual unmasking is implemented in later patches in this patch series.

> Thanks,
> 
> 	M.
> 	
> > +
> > +	/* Unmask summary MSI interrupt */
> > +	reg = advk_readl(pcie, PCIE_ISR0_MASK_REG);
> > +	reg &= ~PCIE_ISR0_MSI_INT_PENDING;
> > +	advk_writel(pcie, reg, PCIE_ISR0_MASK_REG);
> >  
> >  	/* Enable summary interrupt for GIC SPI source */
> >  	reg = PCIE_IRQ_ALL_MASK & (~PCIE_IRQ_ENABLE_INTS_MASK);
> > @@ -1049,7 +1053,7 @@ static void advk_pcie_handle_msi(struct advk_pcie *pcie)
> >  
> >  	msi_mask = advk_readl(pcie, PCIE_MSI_MASK_REG);
> >  	msi_val = advk_readl(pcie, PCIE_MSI_STATUS_REG);
> > -	msi_status = msi_val & ~msi_mask;
> > +	msi_status = msi_val & ((~msi_mask) & PCIE_MSI_ALL_MASK);
> >  
> >  	for (msi_idx = 0; msi_idx < MSI_IRQ_NUM; msi_idx++) {
> >  		if (!(BIT(msi_idx) & msi_status))
> > -- 
> > 2.20.1
> > 
> > 
> 
> -- 
> Without deviation from the norm, progress is not possible.