Re: [PATCH v3 07/12] PCI: rockchip-ep: Refactor rockchip_pcie_ep_probe() MSI-X hiding

Manivannan Sadhasivam
2024-10-10T07:25:19Z

On Mon, Oct 07, 2024 at 01:12:13PM +0900, Damien Le Moal wrote:
> Move the code in rockchip_pcie_ep_probe() to hide the MSI-X capability
> to its own function, rockchip_pcie_ep_hide_msix_cap(). No functional
> changes.
>
> Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

Btw, can someone from Rockchip confirm if this hiding is necessary for all the
SoCs? It looks to me like an SoC quirk.

- Mani

> ---
> drivers/pci/controller/pcie-rockchip-ep.c | 54 +++++++++++++----------
> 1 file changed, 30 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/pci/controller/pcie-rockchip-ep.c b/drivers/pci/controller/pcie-rockchip-ep.c
> index 523e9cdfd241..7a1798fcc2ad 100644
> --- a/drivers/pci/controller/pcie-rockchip-ep.c
> +++ b/drivers/pci/controller/pcie-rockchip-ep.c
> @@ -581,6 +581,34 @@ static void rockchip_pcie_ep_release_resources(struct rockchip_pcie_ep *ep)
> pci_epc_mem_exit(ep->epc);
> }
>
> +static void rockchip_pcie_ep_hide_msix_cap(struct rockchip_pcie *rockchip)
> +{
> + u32 cfg_msi, cfg_msix_cp;
> +
> + /*
> + * MSI-X is not supported but the controller still advertises the MSI-X
> + * capability by default, which can lead to the Root Complex side
> + * allocating MSI-X vectors which cannot be used. Avoid this by skipping
> + * the MSI-X capability entry in the PCIe capabilities linked-list: get
> + * the next pointer from the MSI-X entry and set that in the MSI
> + * capability entry (which is the previous entry). This way the MSI-X
> + * entry is skipped (left out of the linked-list) and not advertised.
> + */
> + cfg_msi = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
> + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
> +
> + cfg_msi &= ~ROCKCHIP_PCIE_EP_MSI_CP1_MASK;
> +
> + cfg_msix_cp = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
> + ROCKCHIP_PCIE_EP_MSIX_CAP_REG) &
> + ROCKCHIP_PCIE_EP_MSIX_CAP_CP_MASK;
> +
> + cfg_msi |= cfg_msix_cp;
> +
> + rockchip_pcie_write(rockchip, cfg_msi,
> + PCIE_EP_CONFIG_BASE + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
> +}
> +
> static int rockchip_pcie_ep_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> @@ -588,7 +616,6 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
> struct rockchip_pcie *rockchip;
> struct pci_epc *epc;
> int err;
> - u32 cfg_msi, cfg_msix_cp;
>
> ep = devm_kzalloc(dev, sizeof(*ep), GFP_KERNEL);
> if (!ep)
> @@ -619,6 +646,8 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
> if (err)
> goto err_disable_clocks;
>
> + rockchip_pcie_ep_hide_msix_cap(rockchip);
> +
> /* Establish the link automatically */
> rockchip_pcie_write(rockchip, PCIE_CLIENT_LINK_TRAIN_ENABLE,
> PCIE_CLIENT_CONFIG);
> @@ -626,29 +655,6 @@ static int rockchip_pcie_ep_probe(struct platform_device *pdev)
> /* Only enable function 0 by default */
> rockchip_pcie_write(rockchip, BIT(0), PCIE_CORE_PHY_FUNC_CFG);
>
> - /*
> - * MSI-X is not supported but the controller still advertises the MSI-X
> - * capability by default, which can lead to the Root Complex side
> - * allocating MSI-X vectors which cannot be used. Avoid this by skipping
> - * the MSI-X capability entry in the PCIe capabilities linked-list: get
> - * the next pointer from the MSI-X entry and set that in the MSI
> - * capability entry (which is the previous entry). This way the MSI-X
> - * entry is skipped (left out of the linked-list) and not advertised.
> - */
> - cfg_msi = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
> - ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
> -
> - cfg_msi &= ~ROCKCHIP_PCIE_EP_MSI_CP1_MASK;
> -
> - cfg_msix_cp = rockchip_pcie_read(rockchip, PCIE_EP_CONFIG_BASE +
> - ROCKCHIP_PCIE_EP_MSIX_CAP_REG) &
> - ROCKCHIP_PCIE_EP_MSIX_CAP_CP_MASK;
> -
> - cfg_msi |= cfg_msix_cp;
> -
> - rockchip_pcie_write(rockchip, cfg_msi,
> - PCIE_EP_CONFIG_BASE + ROCKCHIP_PCIE_EP_MSI_CTRL_REG);
> -
> rockchip_pcie_write(rockchip, PCIE_CLIENT_CONF_ENABLE,
> PCIE_CLIENT_CONFIG);
>
> --
> 2.46.2
>

--
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