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

Manivannan Sadhasivam
2024-10-10T08:10:03Z

On Thu, Oct 10, 2024 at 12:55:12PM +0530, Manivannan Sadhasivam wrote:
> 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)

Perhaps a better name would be rockchip_pcie_disable_broken_msix()? As the
function essentially disables MSIx which is broken. Again, it'd be good to know
if this applies to all SoCs or just a few.

- Mani

> > +{
> > + 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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