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Date:   Thu, 21 Oct 2021 20:49:13 +0530
From:   Naveen Naidu <naveennaidu479@gmail.com>
To:     bhelgaas@google.com
Cc:     linux-kernel-mentees@lists.linuxfoundation.org,
        linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        skhan@linuxfoundation.org,
        Nirmal Patel <nirmal.patel@linux.intel.com>,
        Jonathan Derrick <jonathan.derrick@linux.dev>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Rob Herring <robh@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>
Subject: Re: [PATCH v3 17/25] PCI: vmd: Use RESPONSE_IS_PCI_ERROR() to check
 read from hardware
Message-ID: <20211021151913.nmnvfhqnyepnfok2@theprophet>
References: <cover.1634825082.git.naveennaidu479@gmail.com>
 <5be1fdfdcf4b4a453117ef4dea0f71c9555fac24.1634825082.git.naveennaidu479@gmail.com>
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On 21/10, Naveen Naidu wrote:
> An MMIO read from a PCI device that doesn't exist or doesn't respond
> causes a PCI error.  There's no real data to return to satisfy the
> CPU read, so most hardware fabricates ~0 data.
> 
> Use RESPONSE_IS_PCI_ERROR() to check the response we get when we read
> data from hardware.
> 
> This helps unify PCI error response checking and make error checks
> consistent and easier to find.
> 
> Signed-off-by: Naveen Naidu <naveennaidu479@gmail.com>
> ---
>  drivers/pci/controller/vmd.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
> index a5987e52700e..bfe6b002ffec 100644
> --- a/drivers/pci/controller/vmd.c
> +++ b/drivers/pci/controller/vmd.c
> @@ -538,7 +538,7 @@ static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool native_hint,
>  		int ret;
>  
>  		ret = pci_read_config_dword(dev, PCI_REG_VMLOCK, &vmlock);
> -		if (ret || vmlock == ~0)
> +		if (ret || RESPONSE_IS_PCI_ERROR(vmlock))
>  			return -ENODEV;
>  
>  		if (MB2_SHADOW_EN(vmlock)) {
> -- 
> 2.25.1
> 

Jonathan, I haven't added your Reviewed-by tag to this patch which you
gave in v1 of the series [1] , because the macro definition of the
RESPONSE_IS_PCI_ERROR changed slightly, and I was not sure if you would
be okay with it. I hope it was right thing to do, if not I apologize for
that.

[1]:
https://lore.kernel.org/linux-pci/f3aca934-7dee-b294-ad3c-264e773eddda@linux.dev/T/#u

Thanks,
Naveen