From: Florian Fainelli <f.fainelli@gmail.com>
To: Jeremy Linton <jeremy.linton@arm.com>,
nicolas saenz julienne <nsaenz@kernel.org>,
linux-pci@vger.kernel.org
Cc: lorenzo.pieralisi@arm.com, bhelgaas@google.com,
rjw@rjwysocki.net, lenb@kernel.org, robh@kernel.org,
kw@linux.com, f.fainelli@gmail.com,
bcm-kernel-feedback-list@broadcom.com,
linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-rpi-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 2/4] PCI: brcmstb: Add ACPI config space quirk
Date: Mon, 30 Aug 2021 09:27:26 -0700 [thread overview]
Message-ID: <f6860e38-c6fa-292d-f1a1-22b3e4b48f32@gmail.com> (raw)
In-Reply-To: <5c39cf29-a08f-48d1-b873-ce0fda763d66@arm.com>
On 8/30/2021 9:23 AM, Jeremy Linton wrote:
> Hi,
>
> On 8/30/21 3:36 AM, nicolas saenz julienne wrote:
>> Hi Jeremy,
>> sorry for the late reply, I've been on vacation.
>>
>> On Thu, 2021-08-26 at 02:15 -0500, Jeremy Linton wrote:
>>
>> [...]
>>
>>> +static void __iomem *brcm_pcie_map_conf2(struct pci_bus *bus,
>>> + unsigned int devfn, int where)
>>> +{
>>> + struct pci_config_window *cfg = bus->sysdata;
>>> + void __iomem *base = cfg->win;
>>> + int idx;
>>> + u32 up;
>>> +
>>> + /* Accesses to the RC go right to the RC registers if slot==0 */
>>> + if (pci_is_root_bus(bus))
>>> + return PCI_SLOT(devfn) ? NULL : base + where;
>>> +
>>> + /*
>>> + * Assure the link is up before sending requests downstream.
>>> This is done
>>> + * to avoid sending transactions to EPs that don't exist. Link flap
>>> + * conditions/etc make this race more probable. The resulting
>>> unrecoverable
>>> + * SERRORs will result in the machine crashing.
>>> + */
>>> + up = readl(base + PCIE_MISC_PCIE_STATUS);
>>> + if (!(up & PCIE_MISC_PCIE_STATUS_PCIE_DL_ACTIVE_MASK))
>>> + return NULL;
>>> +
>>> + if (!(up & PCIE_MISC_PCIE_STATUS_PCIE_PHYLINKUP_MASK))
>>> + return NULL;
>>
>> Couldn't this be integrated in the original brcm_pcie_map_conf()? IIUC
>> there is
>> nothing ACPI specific about it. It'd also make for less code duplication.
>
> That is where I started with this, but it wasn't the linkup check/etc
> which caused me to hoist it but the fact that if ACPI quirks are enabled
> they end up statically built into the kernel. While if this host bridge
> is enabled, it can end up being a module, and the resulting mess I
> created trying to satisfy the CONFIG variations. I'm not much of a fan
> of copy/paste programming, but that IMHO ended up being the cleanest here.
>
Agreed, the open coding that is being done is reasonable IHMO, although
we may have to update the link up code in both pcie-brcmstb.c and this
file in the future if offsets/bits do change, nothing impossible though.
--
Florian
next prev parent reply other threads:[~2021-08-30 16:27 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-26 7:15 [PATCH v3 0/4] CM4 ACPI PCIe quirk Jeremy Linton
2021-08-26 7:15 ` [PATCH v3 1/4] PCI: brcmstb: Break register definitions into separate header Jeremy Linton
2021-08-30 8:37 ` nicolas saenz julienne
2021-08-26 7:15 ` [PATCH v3 2/4] PCI: brcmstb: Add ACPI config space quirk Jeremy Linton
2021-08-30 8:36 ` nicolas saenz julienne
2021-08-30 16:23 ` Jeremy Linton
2021-08-30 16:27 ` Florian Fainelli [this message]
2021-08-30 17:17 ` nicolas saenz julienne
2021-10-05 15:32 ` Bjorn Helgaas
2021-10-05 15:57 ` Jeremy Linton
2021-10-05 19:43 ` Pali Rohár
2021-10-05 22:25 ` Jeremy Linton
2021-10-06 2:07 ` Florian Fainelli
2021-10-22 17:04 ` Florian Fainelli
2021-10-22 17:17 ` Pali Rohár
2021-10-22 17:29 ` Florian Fainelli
2021-10-22 17:57 ` Pali Rohár
2021-08-26 7:15 ` [PATCH v3 3/4] PCI/ACPI: Add Broadcom bcm2711 MCFG quirk Jeremy Linton
2021-08-30 8:37 ` nicolas saenz julienne
2021-09-13 16:12 ` Rafael J. Wysocki
2021-10-05 15:10 ` Bjorn Helgaas
2021-10-05 15:43 ` Jeremy Linton
2021-10-05 22:31 ` Bjorn Helgaas
2021-10-05 23:32 ` Jeremy Linton
2021-10-05 20:02 ` Pali Rohár
2021-10-05 22:44 ` Jeremy Linton
2021-08-26 7:15 ` [PATCH v3 4/4] MAINTAINERS: Widen brcmstb PCIe file scope Jeremy Linton
2021-08-30 8:38 ` nicolas saenz julienne
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