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

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Date:   Fri, 16 Aug 2019 02:58:31 +0000
From:   Xiaowei Bao <xiaowei.bao@....com>
To:     Andrew Murray <andrew.murray@....com>
CC:     "jingoohan1@...il.com" <jingoohan1@...il.com>,
        "gustavo.pimentel@...opsys.com" <gustavo.pimentel@...opsys.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Leo Li <leoyang.li@....com>, "kishon@...com" <kishon@...com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "M.h. Lian" <minghuan.lian@....com>,
        Mingkai Hu <mingkai.hu@....com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "Z.q. Hou" <zhiqiang.hou@....com>
Subject: RE: [PATCH 02/10] PCI: designware-ep: Add the doorbell mode of MSI-X
 in EP mode



> -----Original Message-----
> From: Andrew Murray <andrew.murray@....com>
> Sent: 2019年8月15日 19:54
> To: Xiaowei Bao <xiaowei.bao@....com>
> Cc: jingoohan1@...il.com; gustavo.pimentel@...opsys.com;
> bhelgaas@...gle.com; robh+dt@...nel.org; mark.rutland@....com;
> shawnguo@...nel.org; Leo Li <leoyang.li@....com>; kishon@...com;
> lorenzo.pieralisi@....com; arnd@...db.de; gregkh@...uxfoundation.org;
> M.h. Lian <minghuan.lian@....com>; Mingkai Hu <mingkai.hu@....com>;
> Roy Zang <roy.zang@....com>; linux-pci@...r.kernel.org;
> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org;
> linux-arm-kernel@...ts.infradead.org; linuxppc-dev@...ts.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@....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....>
> 
> 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.
> 
> 
> >  {
> > 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.
> 
> 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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