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Message-ID: <20161123182243.GF16033@bhelgaas-glaptop.roam.corp.google.com>
Date: Wed, 23 Nov 2016 12:22:43 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Tomasz Nowicki <tn@...ihalf.com>
Cc: arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
rafael@...nel.org, hanjun.guo@...aro.org,
Lorenzo.Pieralisi@....com, okaya@...eaurora.org,
jchandra@...adcom.com, robert.richter@...iumnetworks.com,
mw@...ihalf.com, Liviu.Dudau@....com, ddaney@...iumnetworks.com,
wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
msalter@...hat.com, linux-pci@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
linux-kernel@...r.kernel.org, linaro-acpi@...ts.linaro.org,
jcm@...hat.com, andrea.gallo@...aro.org, dhdang@....com,
jeremy.linton@....com, liudongdong3@...wei.com, cov@...eaurora.org
Subject: Re: [PATCH V9 11/11] ARM64/PCI: Support for ACPI based PCI host
controller
On Wed, Nov 23, 2016 at 12:21:03PM +0100, Tomasz Nowicki wrote:
> Hi Bjorn,
>
> On 23.11.2016 00:13, Bjorn Helgaas wrote:
> >Hi Tomasz,
> >
> >On Fri, Jun 10, 2016 at 09:55:19PM +0200, Tomasz Nowicki wrote:
> >>Implement pci_acpi_scan_root and other arch-specific call so that ARM64
> >>can start using ACPI to setup and enumerate PCI buses.
> >>
> >>Prior to buses enumeration the pci_acpi_scan_root() implementation looks
> >>for configuration space start address (obtained through ACPI _CBA method or
> >>MCFG interface). If succeed, it uses ECAM library to create new mapping.
> >>Then it attaches generic ECAM ops (pci_generic_ecam_ops) which are used
> >>for accessing configuration space later on.
> >>...
> >
> >>+static struct acpi_pci_root_ops acpi_pci_root_ops = {
> >>+ .release_info = pci_acpi_generic_release_info,
> >>+};
> >>+
> >>+/* Interface called from ACPI code to setup PCI host controller */
> >> struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
> >> {
> >>- /* TODO: Should be revisited when implementing PCI on ACPI */
> >>- return NULL;
> >>+ int node = acpi_get_node(root->device->handle);
> >>+ struct acpi_pci_generic_root_info *ri;
> >>+ struct pci_bus *bus, *child;
> >>+
> >>+ ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
> >>+ if (!ri)
> >>+ return NULL;
> >>+
> >>+ ri->cfg = pci_acpi_setup_ecam_mapping(root);
> >>+ if (!ri->cfg) {
> >>+ kfree(ri);
> >>+ return NULL;
> >>+ }
> >>+
> >>+ acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;
> >
> >This has already been merged, but this isn't right, is it? We're
> >writing a host controller-specific pointer into the single system-wide
> >acpi_pci_root_ops, then passing it on to acpi_pci_root_create().
> >
> >Today, I think ri->cfg->ops->pci_ops is always &pci_generic_ecam_ops,
> >from this path:
> >
> > ri->cfg = pci_acpi_setup_ecam_mapping
> > cfg = pci_ecam_create(..., &pci_generic_ecam_ops)
> > cfg = kzalloc(...)
> > cfg->ops = ops # &pci_generic_ecam_ops
> >
> >But we're about to merge the ECAM quirks series, which will mean it
> >may not be &pci_generic_ecam_ops. Even apart from the ECAM quirks, we
> >should avoid this pattern of putting device-specific info in a single
> >shared structure because it's too difficult to verify that it's
> >correct.
> >
>
> Well spotted. I agree, we need to fix this. How about this:
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index fb439c7..31c0e1c 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -152,33 +152,35 @@ static void
> pci_acpi_generic_release_info(struct acpi_pci_root_info *ci)
>
> ri = container_of(ci, struct acpi_pci_generic_root_info, common);
> pci_ecam_free(ri->cfg);
> + kfree(ci->ops);
> kfree(ri);
> }
>
> -static struct acpi_pci_root_ops acpi_pci_root_ops = {
> - .release_info = pci_acpi_generic_release_info,
> -};
> -
> /* Interface called from ACPI code to setup PCI host controller */
> struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
> {
> int node = acpi_get_node(root->device->handle);
> struct acpi_pci_generic_root_info *ri;
> struct pci_bus *bus, *child;
> + struct acpi_pci_root_ops *root_ops;
>
> ri = kzalloc_node(sizeof(*ri), GFP_KERNEL, node);
> if (!ri)
> return NULL;
>
> + root_ops = kzalloc_node(sizeof(*root_ops), GFP_KERNEL, node);
> + if (!root_ops)
> + return NULL;
> +
> ri->cfg = pci_acpi_setup_ecam_mapping(root);
> if (!ri->cfg) {
> kfree(ri);
> + kfree(root_ops);
> return NULL;
> }
>
> - acpi_pci_root_ops.pci_ops = &ri->cfg->ops->pci_ops;
> - bus = acpi_pci_root_create(root, &acpi_pci_root_ops, &ri->common,
> - ri->cfg);
> + root_ops->release_info = pci_acpi_generic_release_info;
> + root_ops->pci_ops = &ri->cfg->ops->pci_ops;
> + bus = acpi_pci_root_create(root, root_ops, &ri->common, ri->cfg);
> if (!bus)
> return NULL;
>
> Of course, this should be the part of ECAM quirks core patches.
>
> The other option we have is to remove "struct pci_ops *pci_ops;"
> from acpi_pci_root_ops structure and pass struct pci_ops as an extra
> argument to acpi_pci_root_create(). What do you think?
I think your patch above is fine and avoids the need to change the x86 and
ia64 code. Would you mind packaging this up with a changelog and
signed-off-by? I can take care of putting it in the ECAM series.
Thanks,
Bjorn
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