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

[Xiaowei Bao <xiaowei.bao@nxp.com>]

> -----Original Message-----
> From: Andrew Murray <andrew.murray@arm.com>
> Sent: 2019年8月16日 18:20
> To: Xiaowei Bao <xiaowei.bao@nxp.com>
> Cc: jingoohan1@gmail.com; gustavo.pimentel@synopsys.com;
> bhelgaas@google.com; robh+dt@kernel.org; mark.rutland@arm.com;
> shawnguo@kernel.org; Leo Li <leoyang.li@nxp.com>; kishon@ti.com;
> lorenzo.pieralisi@arm.com; arnd@arndb.de; gregkh@linuxfoundation.org;
> M.h. Lian <minghuan.lian@nxp.com>; Mingkai Hu <mingkai.hu@nxp.com>;
> linux-pci@vger.kernel.org; devicetree@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linuxppc-dev@lists.ozlabs.org; Z.q. Hou <zhiqiang.hou@nxp.com>
> Subject: Re: [PATCH 02/10] PCI: designware-ep: Add the doorbell mode of
> MSI-X in EP mode
> 
> On Fri, Aug 16, 2019 at 02:58:31AM +0000, Xiaowei Bao wrote:
> >
> >
> > > -----Original Message-----
> > > From: Andrew Murray <andrew.murray@arm.com>
> > > Sent: 2019年8月15日 19:54
> > > To: Xiaowei Bao <xiaowei.bao@nxp.com>
> > > Cc: jingoohan1@gmail.com; gustavo.pimentel@synopsys.com;
> > > bhelgaas@google.com; robh+dt@kernel.org; mark.rutland@arm.com;
> > > shawnguo@kernel.org; Leo Li <leoyang.li@nxp.com>; kishon@ti.com;
> > > lorenzo.pieralisi@arm.com; arnd@arndb.de;
> > > gregkh@linuxfoundation.org; M.h. Lian <minghuan.lian@nxp.com>;
> > > Mingkai Hu <mingkai.hu@nxp.com>; Roy Zang <roy.zang@nxp.com>;
> > > linux-pci@vger.kernel.org; devicetree@vger.kernel.org;
> > > linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> > > linuxppc-dev@lists.ozlabs.org
> > > Subject: Re: [PATCH 02/10] PCI: designware-ep: Add the doorbell mode
> > > of MSI-X in EP mode
> > >
> > > 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@nxp.com>
> > > > ---
> > > >  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?
> > Yes, the hardware provide two way to MSI-X, please check the page 492
> > of
> > DWC_pcie_dm_registers_4.30 Menu.
> > MSIX_DOORBELL_OFF on page 492 0x948 Description: MSI-X Doorbell
> > Register....>
> 
> Thanks for the reference.
> 
> > >
> > > 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)?
> > I am not sure, but I think the dw_pcie_ep_raise_msix_irq function is
> > not correct, because I think we can't get the MSIX table from the
> > address ep->phys_base + tbl_addr, but I also don't know where I can get the
> correct MSIX table.
> 
> Well it looks like this function is used by snps,dw-pcie-ep and snps,dw-pcie,
> perhaps the doorbell mode isn't available on that hardware.
> 
> > >
> > >
> > > >  {
> > > > 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.
> > In fact, I will add the SRIOV support in this file, the SRIOV feature
> > have verified In my board, but I need wait the EP framework SRIOV
> > patch merge, so I defined these two macros.
> 
> I'd suggest adding the VF macros along with the SRIOV feature.
OK, I will remove these two macros. Thanks.
> 
> Thanks,
> 
> Andrew Murray
> 
> > >
> > > 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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