linux-kernel - Re: [PATCH] PCI: aardvark: Fix PCI_EXP

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Date:   Thu, 13 Jun 2019 17:14:41 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Remi Pommarel <repk@...plefau.lt>
Cc:     Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ellie Reeves <ellierevves@...il.com>,
        linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: aardvark: Fix PCI_EXP_RTCTL conf register writing

On Wed, May 22, 2019 at 11:33:49PM +0200, Remi Pommarel wrote:
> PCI_EXP_RTCTL is used to activate PME interrupt only, so writing into it
> should not modify other interrupts' mask (such as ISR0).
> 
> Fixes: 6302bf3ef78d ("PCI: Init PCIe feature bits for managed host bridge alloc")
> Signed-off-by: Remi Pommarel <repk@...plefau.lt>
> ---
> Please note that I will unlikely be able to answer any comments from May
> 24th to June 10th.
> ---
>  drivers/pci/controller/pci-aardvark.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 134e0306ff00..27102d3b4f9c 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -451,10 +451,14 @@ advk_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
>  		advk_writel(pcie, new, PCIE_CORE_PCIEXP_CAP + reg);
>  		break;
>  
> -	case PCI_EXP_RTCTL:
> -		new = (new & PCI_EXP_RTCTL_PMEIE) << 3;
> -		advk_writel(pcie, new, PCIE_ISR0_MASK_REG);
> +	case PCI_EXP_RTCTL: {
> +		/* Only mask/unmask PME interrupt */
> +		u32 val = advk_readl(pcie, PCIE_ISR0_MASK_REG) &
> +			~PCIE_MSG_PM_PME_MASK;
> +		val |= (new & PCI_EXP_RTCTL_PMEIE) << 3;

I know you have not introduced this code but maybe we can
take an opportunity to clarify it (that << 3 shift obfuscates
a bit):

	u32 val = advk_readl(pcie, PCIE_ISR0_MASK_REG) &
			~PCIE_MSG_PM_PME_MASK;

	if (new & PCI_EXP_RTCTL_PMEIE)
		val |= PCIE_MSG_PM_PME_MASK;

	advk_writel(pcie, val, PCIE_ISR0_MASK_REG);
	break;

Or I am not reading the code correctly ?

Regardless, I need Thomas' ACK to proceed.

Lorenzo

> +		advk_writel(pcie, val, PCIE_ISR0_MASK_REG);
>  		break;
> +	}
>  
>  	case PCI_EXP_RTSTA:
>  		new = (new & PCI_EXP_RTSTA_PME) >> 9;
> -- 
> 2.20.1
>