Re: [PATCH v2 9/9] PCI: rockchip: Add parameter check for RK3399 PCIe endpoint core set_msi()

[Damien Le Moal <damien.lemoal@opensource.wdc.com>]

On 2/14/23 23:08, Rick Wertenbroek wrote:
> The RK3399 PCIe endpoint core supports only a single PCIe physcial
> function (function number 0), therefore return -EINVAL if set_msi() is
> called with a function number greater than 0.
> The PCIe standard only allows the multi message capability (MMC) value
> to be up to 0x5 (32 messages), therefore return -EINVAL if set_msi() is
> called with a MMC value of over 0x5.
> 
> Signed-off-by: Rick Wertenbroek <rick.wertenbroek@gmail.com>
> ---
>  drivers/pci/controller/pcie-rockchip-ep.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
> index b7865a94e..80634b690 100644
> --- a/drivers/pci/controller/pcie-rockchip-ep.c
> +++ b/drivers/pci/controller/pcie-rockchip-ep.c
> @@ -294,6 +294,16 @@ static int rockchip_pcie_ep_set_msi(struct pci_epc *epc, u8 fn, u8 vfn,
>  	struct rockchip_pcie *rockchip = &ep->rockchip;
>  	u32 flags;
>  
> +	if (fn) {
> +		dev_err(&epc->dev, "This endpoint controller only supports a single physical function\n");
> +		return -EINVAL;
> +	}

Checking this here is late... Given that at most only one physical
function is supported, the check should be in rockchip_pcie_parse_ep_dt().
Something like:

	err = of_property_read_u8(dev->of_node, "max-functions",
                                  &ep->epc->max_functions);

        if (err < 0 || ep->epc->max_functions > 1)

                ep->epc->max_functions = 1;

And all the macros with the (fn) argument could also be simplified
(argument fn removed) since fn will always be 0.

> +
> +	if (mmc > 0x5) {
> +		dev_err(&epc->dev, "Number of MSI IRQs cannot be more than 32\n");

Long line. Please split it after the comma.

> +		return -EINVAL;
> +	}
> +
>  	flags = rockchip_pcie_read(rockchip,
>  				   ROCKCHIP_PCIE_EP_FUNC_BASE(fn) +
>  				   ROCKCHIP_PCIE_EP_MSI_CTRL_REG);

Another nice cleanup: define ROCKCHIP_PCIE_EP_MSI_CTRL_REG to include the
ROCKCHIP_PCIE_EP_FUNC_BASE(fn) addition so that we do not have to do it
here all the time.

-- 
Damien Le Moal
Western Digital Research