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

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Message-ID: <DM6PR12MB40107A9B97A8DAF32A4C651EDA790@DM6PR12MB4010.namprd12.prod.outlook.com>
Date:   Wed, 6 Nov 2019 09:40:15 +0000
From:   Gustavo Pimentel <Gustavo.Pimentel@...opsys.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Andrew Murray <andrew.murray@....com>,
        Xiaowei Bao <xiaowei.bao@....com>,
        "gustavo.pimentel@...opsys.com" <Gustavo.Pimentel@...opsys.com>
CC:     "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 6:13:18, Kishon Vijay Abraham I <kishon@...com> 
wrote:

Hi, this email slip away from my attention...

> 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?

When I implemented the dw_pcie_ep_raise_msix_irq(), the implementation 
was working quite fine on DesignWare solution. Otherwise, I wouldn't 
submit it to the kernel.
From what I have seen and if I recall well, Xiaowei implementation was 
done having PF's configurated on his solution, which is a configuration 
that I don't have in my solution, I believe this could be the missing 
piece that differs between our 2 implementations.

Since patch submission into the kernel related to msix feature on pcitest 
tool, I didn't touch or re-tested the msix feature by lack of time (other 
projects requires my full attention for now). However is on my roadmap to 
came back to add some other features on DesignWare eDMA driver and I can 
do at that time some tests to see if the 
dw_pcie_ep_raise_msix_irq_doorbell() is compatible or not with my 
solution. If so, I can do some patch to simplify and use the 
dw_pcie_ep_raise_msix_irq_doorbell() if it still works as expected like 
on dw_pcie_ep_raise_msix_irq(). Agree?

Gustavo

> 
> Thanks
> Kishon