linux-kernel - RE: [PATCH V6 2/5] PCI/ACPI: Check platform specific ECAM quirks

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Date:   Fri, 16 Sep 2016 13:42:02 +0000
From:   Gabriele Paoloni <gabriele.paoloni@...wei.com>
To:     Christopher Covington <cov@...eaurora.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        "liudongdong (C)" <liudongdong3@...wei.com>
CC:     Tomasz Nowicki <tn@...ihalf.com>,
        "helgaas@...nel.org" <helgaas@...nel.org>,
        "will.deacon@....com" <will.deacon@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "rafael@...nel.org" <rafael@...nel.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "hanjun.guo@...aro.org" <hanjun.guo@...aro.org>,
        "okaya@...eaurora.org" <okaya@...eaurora.org>,
        "jchandra@...adcom.com" <jchandra@...adcom.com>,
        "dhdang@....com" <dhdang@....com>,
        "ard.biesheuvel@...aro.org" <ard.biesheuvel@...aro.org>,
        "robert.richter@...iumnetworks.com" 
        <robert.richter@...iumnetworks.com>,
        "mw@...ihalf.com" <mw@...ihalf.com>,
        "Liviu.Dudau@....com" <Liviu.Dudau@....com>,
        "ddaney@...iumnetworks.com" <ddaney@...iumnetworks.com>,
        Wangyijing <wangyijing@...wei.com>,
        "msalter@...hat.com" <msalter@...hat.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
        "jcm@...hat.com" <jcm@...hat.com>,
        "andrea.gallo@...aro.org" <andrea.gallo@...aro.org>,
        "jeremy.linton@....com" <jeremy.linton@....com>,
        "jhugo@...eaurora.org" <jhugo@...eaurora.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH V6 2/5] PCI/ACPI: Check platform specific ECAM quirks

Hi Cov

> -----Original Message-----
> From: Christopher Covington [mailto:cov@...eaurora.org]
> Sent: 16 September 2016 13:28
> To: Gabriele Paoloni; Lorenzo Pieralisi; liudongdong (C)
> Cc: Tomasz Nowicki; helgaas@...nel.org; will.deacon@....com;
> catalin.marinas@....com; rafael@...nel.org; arnd@...db.de;
> hanjun.guo@...aro.org; okaya@...eaurora.org; jchandra@...adcom.com;
> dhdang@....com; ard.biesheuvel@...aro.org;
> robert.richter@...iumnetworks.com; mw@...ihalf.com;
> Liviu.Dudau@....com; ddaney@...iumnetworks.com; Wangyijing;
> msalter@...hat.com; linux-pci@...r.kernel.org; linux-arm-
> kernel@...ts.infradead.org; linaro-acpi@...ts.linaro.org;
> jcm@...hat.com; andrea.gallo@...aro.org; jeremy.linton@....com;
> jhugo@...eaurora.org; linux-acpi@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH V6 2/5] PCI/ACPI: Check platform specific ECAM
> quirks
> 
> On 09/16/2016 05:02 AM, Gabriele Paoloni wrote:
> > Hi Lorenzo and Tomasz
> >
> > Many Thanks for looking at this
> >
> >> -----Original Message-----
> >> From: Lorenzo Pieralisi [mailto:lorenzo.pieralisi@....com]
> >> Sent: 15 September 2016 11:59
> >> To: liudongdong (C)
> >> Cc: Tomasz Nowicki; helgaas@...nel.org; will.deacon@....com;
> >> catalin.marinas@....com; rafael@...nel.org; arnd@...db.de;
> >> hanjun.guo@...aro.org; okaya@...eaurora.org; jchandra@...adcom.com;
> >> cov@...eaurora.org; dhdang@....com; ard.biesheuvel@...aro.org;
> >> robert.richter@...iumnetworks.com; mw@...ihalf.com;
> >> Liviu.Dudau@....com; ddaney@...iumnetworks.com; Wangyijing;
> >> msalter@...hat.com; linux-pci@...r.kernel.org; linux-arm-
> >> kernel@...ts.infradead.org; linaro-acpi@...ts.linaro.org;
> >> jcm@...hat.com; andrea.gallo@...aro.org; jeremy.linton@....com;
> >> Gabriele Paoloni; jhugo@...eaurora.org; linux-acpi@...r.kernel.org;
> >> linux-kernel@...r.kernel.org
> >> Subject: Re: [PATCH V6 2/5] PCI/ACPI: Check platform specific ECAM
> >> quirks
> >>
> >> On Tue, Sep 13, 2016 at 07:38:39PM +0800, Dongdong Liu wrote:
> >>
> >> [...]
> >>
> >>> Our host bridge is non ECAM only for the RC bus config space;
> >>> for any other bus underneath the root bus we support ECAM access.
> >>>
> >>> RC config resource with hardcode as DEFINE_RES_MEM(0xb0070000,
> >> SZ_4K),
> >>> EP config resource we get it from MCFG table.
> >>> So we need to override ops, but config resource we only need to
> >> hardcode with RC config resource.
> >>>
> >>> Our host controller ACPI support patch can be found:
> >>> https://lkml.org/lkml/2016/8/31/340
> >>
> >> Sorry I misread your code. IIUC you create an array of resources
> that
> >> represent non-ECAM config space (and incidentally contain debug
> >> registers to check the link status - that you need to check for
> every
> >> given config access (?)), but you still need to have an MCFG entry
> that
> >
> > The link status check is inherited from the designware framework (see
> > http://lxr.free-electrons.com/source/drivers/pci/host/pcie-
> designware.c#L678)
> >
> > However I think that in this case we can just check the link status
> > in our init function and return an error if the link is down
> >
> >> covers the bus number subject to quirk to make sure this mechanism
> >> works. Correct ?
> >
> > Well we need the quirks for the root bus numbers but if read this v6
> > quirk mechanism correctly even if we do not specify an mcfg entry for
> > bus 0 oci_mcfg_match_quirks() is called anyway and we can set our
> > special configuration space addresses for the root buses (i.e. I
> think
> > we can have a clean MCFG table with entries only for those bus ranges
> > that are really ECAM)
> >
> >>
> >> This also means that, with the MCFG tables you have and current
> >> mainline kernel you are able to probe a root bridge (because the
> MCFG
> >> table covers the bus number that is not ECAM), with enumeration
> >> going haywire because it is trying to carry out ECAM accesses on
> >> non-ECAM space.
> >
> > Yes correct, we cannot access the host controller configuration space
> > with our current MCFG table and current Linux mainline
> >
> >>
> >> Is my reading correct ?
> >>
> >> Anyway, that's not stricly related to this discussion, it is time we
> >> converge on this patchset, we can add a domain range if that
> >> simplifies things.
> >
> > IMO it would be better to have the domain range to avoid
> > a very large and repetitive static quirk array
> 
> The v6 framework requires what, 21 additional lines of quirk data? What
> if you were to define some preprocessor macros to slim it down? I think
> something like the following would bring it down to roughly 7
> additional
> lines.

Thanks, yes this would work as well. To be honest this is not a big issue.
So either we go this way or we introduce domain range...

Cheers

Gab

> 
> #define PCI_ACPI_QUIRK_QUAD_DOM(rev, dom, ops) \
>     { "HISI ", rev, 0, dom+0, MCFG_BUS_ANY, ops,
>       MCFG_RES_EMPTY}, \
>     { "HISI ", rev, 0, dom+1, MCFG_BUS_ANY, ops,
>       MCFG_RES_EMPTY}, \
>     { "HISI ", rev, 0, dom+2, MCFG_BUS_ANY, ops,
>       MCFG_RES_EMPTY}, \
>     { "HISI ", rev, 0, dom+3, MCFG_BUS_ANY, ops,
>       MCFG_RES_EMPTY},
> 
> PCI_ACPI_QUIRK_QUAD_DOM("HIP05 ", 0, &hisi_pcie_hip05_ops)
> PCI_ACPI_QUIRK_QUAD_DOM("HIP06 ", 0, &hisi_pcie_hip05_ops)
> PCI_ACPI_QUIRK_QUAD_DOM("HIP07 ", 0, &hisi_pcie_hip06_ops)
> PCI_ACPI_QUIRK_QUAD_DOM("HIP07 ", 4, &hisi_pcie_hip07_ops)
> PCI_ACPI_QUIRK_QUAD_DOM("HIP07 ", 8, &hisi_pcie_hip07_ops)
> PCI_ACPI_QUIRK_QUAD_DOM("HIP07 ", 12, &hisi_pcie_hip07_ops)
> 
> Cov
> --
> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
> Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code
> Aurora Forum, a Linux Foundation Collaborative Project.