linux-kernel - Re: [PATCH v2 07/10] PCI: layerscape: Modify the MSIX to the doorbell way

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Message-ID: <20191105123739.GB26960@e121166-lin.cambridge.arm.com>
Date:   Tue, 5 Nov 2019 12:37:39 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Andrew Murray <andrew.murray@....com>,
        Xiaowei Bao <xiaowei.bao@....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>,
        "lorenzo.pieralisi@....co" <lorenzo.pieralisi@....co>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "M.h. Lian" <minghuan.lian@....com>,
        Mingkai Hu <mingkai.hu@....com>, Roy Zang <roy.zang@....com>,
        "jingoohan1@...il.com" <jingoohan1@...il.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>
Subject: Re: [PATCH v2 07/10] PCI: layerscape: Modify the MSIX to the
 doorbell way

On Thu, Aug 29, 2019 at 10:43:18AM +0530, Kishon Vijay Abraham I wrote:
> Gustavo,
> 
> On 27/08/19 6:55 PM, Andrew Murray wrote:
> > On Sat, Aug 24, 2019 at 12:08:40AM +0000, Xiaowei Bao wrote:
> >>
> >>
> >>> -----Original Message-----
> >>> From: Andrew Murray <andrew.murray@....com>
> >>> Sent: 2019年8月23日 21:58
> >>> To: Xiaowei Bao <xiaowei.bao@....com>
> >>> Cc: bhelgaas@...gle.com; robh+dt@...nel.org; mark.rutland@....com;
> >>> shawnguo@...nel.org; Leo Li <leoyang.li@....com>; kishon@...com;
> >>> lorenzo.pieralisi@....co; arnd@...db.de; gregkh@...uxfoundation.org; M.h.
> >>> Lian <minghuan.lian@....com>; Mingkai Hu <mingkai.hu@....com>; Roy
> >>> Zang <roy.zang@....com>; jingoohan1@...il.com;
> >>> gustavo.pimentel@...opsys.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 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.
> 
> Gustavo, can you confirm dw_pcie_ep_raise_msix_irq() works for
> designware as it didn't work for both me and Xiaowei?

This question needs an answer.

Thanks,
Lorenzo