From: Lukas Wunner <lukas@wunner.de>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: linux-pci@vger.kernel.org,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
"Maciej W . Rozycki" <macro@orcam.me.uk>,
"Mika Westerberg" <mika.westerberg@linux.intel.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
"Mario Limonciello" <mario.limonciello@amd.com>,
"Duc Dang" <ducdang@google.com>,
"Alex Williamson" <alex.williamson@redhat.com>,
linux-kernel@vger.kernel.org,
"Bjorn Helgaas" <bhelgaas@google.com>
Subject: Re: [RFC PATCH 1/3] PCI: Wait for device readiness with Configuration RRS
Date: Wed, 28 Aug 2024 06:17:04 +0200 [thread overview]
Message-ID: <Zs6kwHX7EIGvnf9_@wunner.de> (raw)
In-Reply-To: <20240827234848.4429-2-helgaas@kernel.org>
On Tue, Aug 27, 2024 at 06:48:46PM -0500, Bjorn Helgaas wrote:
> @@ -1311,9 +1320,15 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
> return -ENOTTY;
> }
>
> - pci_read_config_dword(dev, PCI_COMMAND, &id);
> - if (!PCI_POSSIBLE_ERROR(id))
> - break;
> + if (root && root->config_crs_sv) {
> + pci_read_config_dword(dev, PCI_VENDOR_ID, &id);
> + if (!pci_bus_crs_vendor_id(id))
> + break;
There was an effort from Amazon back in 2020/2021 to improve CRS support:
https://lore.kernel.org/linux-pci/20200307172044.29645-1-stanspas@amazon.com/
One suggestion you raised in the subsequent discussion was to use a
16-bit (word) instead of a 32-bit (dword) read of the Vendor ID
register to avoid issues with devices that don't implement CRS SV
correctly:
https://lore.kernel.org/linux-pci/20210913160745.GA1329939@bjorn-Precision-5520/
I realize that pci_bus_crs_vendor_id() masks the Device ID bits,
so probably no biggie. Just want to make sure all lessons learned
during previous discussions on this topic are considered. :)
Thanks,
Lukas
next prev parent reply other threads:[~2024-08-28 4:17 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-27 23:48 [RFC PATCH 0/3] PCI: Use Configuration RRS to wait for device ready Bjorn Helgaas
2024-08-27 23:48 ` [RFC PATCH 1/3] PCI: Wait for device readiness with Configuration RRS Bjorn Helgaas
2024-08-28 4:17 ` Lukas Wunner [this message]
2024-08-28 20:53 ` Bjorn Helgaas
2024-09-11 0:42 ` Duc Dang
2024-08-27 23:48 ` [RFC PATCH 2/3] PCI: aardvark: Correct Configuration RRS checking Bjorn Helgaas
2024-08-27 23:48 ` [RFC PATCH 3/3] PCI: Rename CRS Completion Status to RRS Bjorn Helgaas
2024-08-28 21:24 ` [RFC PATCH 0/3] PCI: Use Configuration RRS to wait for device ready Mario Limonciello
2024-08-28 21:42 ` Bjorn Helgaas
2024-08-28 22:26 ` Mario Limonciello
2024-08-29 23:12 ` Bjorn Helgaas
2024-09-10 0:59 ` Bjorn Helgaas
2024-09-10 22:55 ` Bjorn Helgaas
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