linux-kernel - Re: [PATCH 09/22] PCI: aardvark: Use SET_PCI_ERROR

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Message-ID: <20211011180850.hgp4ctykvus37fx7@pali>
Date:   Mon, 11 Oct 2021 20:08:50 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Naveen Naidu <naveennaidu479@...il.com>
Cc:     bhelgaas@...gle.com,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        "moderated list:PCI DRIVER FOR AARDVARK (Marvell Armada 3700)" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 09/22] PCI: aardvark: Use SET_PCI_ERROR_RESPONSE() when
 device not found

On Monday 11 October 2021 23:26:33 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 SET_PCI_ERROR_RESPONSE() to set the error response, when a faulty
> read occurs.
> 
> This helps unify PCI error response checking and make error check
> consistent and easier to find.
> 
> Compile tested only.
> 
> Signed-off-by: Naveen Naidu <naveennaidu479@...il.com>
> ---
>  drivers/pci/controller/pci-aardvark.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c
> index 596ebcfcc82d..dc2f820ef55f 100644
> --- a/drivers/pci/controller/pci-aardvark.c
> +++ b/drivers/pci/controller/pci-aardvark.c
> @@ -894,7 +894,7 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
>  	int ret;
>  
>  	if (!advk_pcie_valid_device(pcie, bus, devfn)) {
> -		*val = 0xffffffff;
> +		SET_PCI_ERROR_RESPONSE(val);

Hello! Now I'm looking at this macro, and should not it depends on
"size" argument? If doing 8-bit or 16-bit read operation then should not
it rather sets only low 8 bits or low 16 bits to ones?

>  		return PCIBIOS_DEVICE_NOT_FOUND;
>  	}
>  
> @@ -920,7 +920,7 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
>  			*val = CFG_RD_CRS_VAL;
>  			return PCIBIOS_SUCCESSFUL;
>  		}
> -		*val = 0xffffffff;
> +		SET_PCI_ERROR_RESPONSE(val);
>  		return PCIBIOS_SET_FAILED;
>  	}
>  
> @@ -955,14 +955,14 @@ static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn,
>  			*val = CFG_RD_CRS_VAL;
>  			return PCIBIOS_SUCCESSFUL;
>  		}
> -		*val = 0xffffffff;
> +		SET_PCI_ERROR_RESPONSE(val);
>  		return PCIBIOS_SET_FAILED;
>  	}
>  
>  	/* Check PIO status and get the read result */
>  	ret = advk_pcie_check_pio_status(pcie, allow_crs, val);
>  	if (ret < 0) {
> -		*val = 0xffffffff;
> +		SET_PCI_ERROR_RESPONSE(val);
>  		return PCIBIOS_SET_FAILED;
>  	}
>  
> -- 
> 2.25.1
>