linux-kernel - Re: [PATCH v2 4/4] PCI: cadence: Fix to read 32-bit Vendor ID/Device ID property from DT

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Date:   Fri, 1 May 2020 16:11:31 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Tom Joseph <tjoseph@...ence.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        linux-pci@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] PCI: cadence: Fix to read 32-bit Vendor ID/Device
 ID property from DT

On Fri, Apr 17, 2020 at 05:13:22PM +0530, Kishon Vijay Abraham I wrote:
> The PCI Bus Binding specification (IEEE Std 1275-1994 Revision 2.1 [1])
> defines both Vendor ID and Device ID to be 32-bits. Fix
> pcie-cadence-host.c driver to read 32-bit Vendor ID and Device ID
> properties from device tree.
> 
> [1] -> https://www.devicetree.org/open-firmware/bindings/pci/pci2_1.pdf
> 
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> ---
>  drivers/pci/controller/cadence/pcie-cadence-host.c | 4 ++--
>  drivers/pci/controller/cadence/pcie-cadence.h      | 4 ++--
>  2 files changed, 4 insertions(+), 4 deletions(-)

I don't see how you would use a 32-bit value for a 16-bit register so
certainly the struct cdns_pcie_rc fields size is questionable anyway.

I *assume* you are referring to 4.1.2.1 and the property list
encoded as "encode-int".

I would like to get RobH's opinion on this - I don't know myself
whether the PCI OF bindings you added are still relevant and how
they should be interpreted.

Thanks
Lorenzo

> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index 8f72967f298f..31e67c9c88cf 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -229,10 +229,10 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
>  	}
>  
>  	rc->vendor_id = 0xffff;
> -	of_property_read_u16(np, "vendor-id", &rc->vendor_id);
> +	of_property_read_u32(np, "vendor-id", &rc->vendor_id);
>  
>  	rc->device_id = 0xffff;
> -	of_property_read_u16(np, "device-id", &rc->device_id);
> +	of_property_read_u32(np, "device-id", &rc->device_id);
>  
>  	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "reg");
>  	pcie->reg_base = devm_ioremap_resource(dev, res);
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index 6bd89a21bb1c..df14ad002fe9 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -262,8 +262,8 @@ struct cdns_pcie_rc {
>  	struct resource		*bus_range;
>  	void __iomem		*cfg_base;
>  	u32			no_bar_nbits;
> -	u16			vendor_id;
> -	u16			device_id;
> +	u32			vendor_id;
> +	u32			device_id;
>  };
>  
>  /**
> -- 
> 2.17.1
>