RE: [PATCH v2 07/10] PCI: layerscape: Modify the MSIX to the doorbell way

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

> -----Original Message-----
> From: Andrew Murray <andrew.murray@arm.com>
> Sent: 2019年8月27日 21:25
> To: Xiaowei Bao <xiaowei.bao@nxp.com>
> Cc: 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.co; 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>; jingoohan1@gmail.com;
> gustavo.pimentel@synopsys.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 v2 07/10] PCI: layerscape: Modify the MSIX to the
> doorbell way
> 
> On Sat, Aug 24, 2019 at 12:08:40AM +0000, Xiaowei Bao wrote:
> >
> >
> > > -----Original Message-----
> > > From: Andrew Murray <andrew.murray@arm.com>
> > > Sent: 2019年8月23日 21:58
> > > To: Xiaowei Bao <xiaowei.bao@nxp.com>
> > > Cc: 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.co; 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>; jingoohan1@gmail.com;
> > > gustavo.pimentel@synopsys.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 v2 07/10] PCI: layerscape: Modify the MSIX to
> > > the doorbell way
> > >
> > > On Thu, Aug 22, 2019 at 07:22:39PM +0800, Xiaowei Bao wrote:
> > > > The layerscape platform use the doorbell way to trigger MSIX
> > > > interrupt in EP mode.
> > > >
> > >
> > > I have no problems with this patch, however...
> > >
> > > Are you able to add to this message a reason for why you are making
> > > this change? Did dw_pcie_ep_raise_msix_irq not work when func_no !=
> > > 0? Or did it work yet dw_pcie_ep_raise_msix_irq_doorbell is more
> efficient?
> >
> > The fact is that, this driver is verified in ls1046a platform of NXP
> > before, and ls1046a don't support MSIX feature, so I set the
> > msix_capable of pci_epc_features struct is false, but in other
> > platform, e.g. ls1088a, it support the MSIX feature, I verified the MSIX
> feature in ls1088a, it is not OK, so I changed to another way. Thanks.
> 
> Right, so the existing pci-layerscape-ep.c driver never supported MSIX yet it
> erroneously had a switch case statement to call dw_pcie_ep_raise_msix_irq
> which would never get used.
> 
> Now that we're adding a platform with MSIX support the existing
> dw_pcie_ep_raise_msix_irq doesn't work (for this platform) so we are adding
> a different method.
> 
> Given that dw_pcie_ep_raise_msix_irq is used by pcie-designware-plat.c we
> can assume this function at least works for it's use case.
> 
> Please update the commit message - It would be helpful to suggest that
> dw_pcie_ep_raise_msix_irq was never called in the exisitng driver because
> msix_capable was always set to false.

Agree, this is much clearer, I will modify the commit message in the next version patch,
thanks a lot.

> 
> Thanks,
> 
> Andrew Murray
> 
> >
> > >
> > > Thanks,
> > >
> > > Andrew Murray
> > >
> > > > Signed-off-by: Xiaowei Bao <xiaowei.bao@nxp.com>
> > > > ---
> > > > v2:
> > > >  - No change.
> > > >
> > > >  drivers/pci/controller/dwc/pci-layerscape-ep.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/pci/controller/dwc/pci-layerscape-ep.c
> > > > b/drivers/pci/controller/dwc/pci-layerscape-ep.c
> > > > index 8461f62..7ca5fe8 100644
> > > > --- a/drivers/pci/controller/dwc/pci-layerscape-ep.c
> > > > +++ b/drivers/pci/controller/dwc/pci-layerscape-ep.c
> > > > @@ -74,7 +74,8 @@ static int ls_pcie_ep_raise_irq(struct
> > > > dw_pcie_ep *ep,
> > > u8 func_no,
> > > >  	case PCI_EPC_IRQ_MSI:
> > > >  		return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
> > > >  	case PCI_EPC_IRQ_MSIX:
> > > > -		return dw_pcie_ep_raise_msix_irq(ep, func_no,
> interrupt_num);
> > > > +		return dw_pcie_ep_raise_msix_irq_doorbell(ep, func_no,
> > > > +							  interrupt_num);
> > > >  	default:
> > > >  		dev_err(pci->dev, "UNKNOWN IRQ type\n");
> > > >  		return -EINVAL;
> > > > --
> > > > 2.9.5
> > > >