Re: [PATCH 02/10] PCI: designware-ep: Add the doorbell mode of MSI-X in EP mode

From: Andrew Murray
Date: Thu Aug 15 2019 - 07:53:45 EST


On Thu, Aug 15, 2019 at 04:37:08PM +0800, Xiaowei Bao wrote:
> Add the doorbell mode of MSI-X in EP mode.
>
> Signed-off-by: Xiaowei Bao <xiaowei.bao@xxxxxxx>
> ---
> drivers/pci/controller/dwc/pcie-designware-ep.c | 14 ++++++++++++++
> drivers/pci/controller/dwc/pcie-designware.h | 14 ++++++++++++++
> 2 files changed, 28 insertions(+)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 75e2955..e3a7cdf 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -454,6 +454,20 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
> return 0;
> }
>
> +int dw_pcie_ep_raise_msix_irq_doorbell(struct dw_pcie_ep *ep, u8 func_no,
> + u16 interrupt_num)
> +{
> + struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
> + u32 msg_data;
> +
> + msg_data = (func_no << PCIE_MSIX_DOORBELL_PF_SHIFT) |
> + (interrupt_num - 1);
> +
> + dw_pcie_writel_dbi(pci, PCIE_MSIX_DOORBELL, msg_data);
> +
> + return 0;
> +}
> +
> int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
> u16 interrupt_num)

Have I understood correctly that the hardware provides an alternative mechanism
that allows for raising MSI-X interrupts without the bother of reading the
capabilities registers?

If so is there any good reason to keep dw_pcie_ep_raise_msix_irq? (And thus use
it in dw_plat_pcie_ep_raise_irq also)?


> {
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 2b291e8..cd903e9 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -88,6 +88,11 @@
> #define PCIE_MISC_CONTROL_1_OFF 0x8BC
> #define PCIE_DBI_RO_WR_EN BIT(0)
>
> +#define PCIE_MSIX_DOORBELL 0x948
> +#define PCIE_MSIX_DOORBELL_PF_SHIFT 24
> +#define PCIE_MSIX_DOORBELL_VF_SHIFT 16
> +#define PCIE_MSIX_DOORBELL_VF_ACTIVE BIT(15)

The _VF defines are not used, I'd suggest removing them.

Thanks,

Andrew Murray

> +
> /*
> * iATU Unroll-specific register definitions
> * From 4.80 core version the address translation will be made by unroll
> @@ -399,6 +404,8 @@ int dw_pcie_ep_raise_msi_irq(struct dw_pcie_ep *ep, u8 func_no,
> u8 interrupt_num);
> int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
> u16 interrupt_num);
> +int dw_pcie_ep_raise_msix_irq_doorbell(struct dw_pcie_ep *ep, u8 func_no,
> + u16 interrupt_num);
> void dw_pcie_ep_reset_bar(struct dw_pcie *pci, enum pci_barno bar);
> #else
> static inline void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
> @@ -431,6 +438,13 @@ static inline int dw_pcie_ep_raise_msix_irq(struct dw_pcie_ep *ep, u8 func_no,
> return 0;
> }
>
> +static inline int dw_pcie_ep_raise_msix_irq_doorbell(struct dw_pcie_ep *ep,
> + u8 func_no,
> + u16 interrupt_num)
> +{
> + return 0;
> +}
> +
> static inline void dw_pcie_ep_reset_bar(struct dw_pcie *pci, enum pci_barno bar)
> {
> }
> --
> 2.9.5
>
>
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