From: Bjorn Helgaas <helgaas@kernel.org>
To: Terry Bowman <terry.bowman@amd.com>
Cc: dave@stgolabs.net, jonathan.cameron@huawei.com,
dave.jiang@intel.com, alison.schofield@intel.com,
dan.j.williams@intel.com, bhelgaas@google.com,
shiju.jose@huawei.com, ming.li@zohomail.com,
Smita.KoralahalliChannabasappa@amd.com, rrichter@amd.com,
dan.carpenter@linaro.org, PradeepVineshReddy.Kodamati@amd.com,
lukas@wunner.de, Benjamin.Cheatham@amd.com,
sathyanarayanan.kuppuswamy@linux.intel.com,
linux-cxl@vger.kernel.org, alucerop@amd.com, ira.weiny@intel.com,
linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org
Subject: Re: [PATCH v13 02/25] PCI/CXL: Introduce pcie_is_cxl()
Date: Fri, 5 Dec 2025 18:45:50 -0600 [thread overview]
Message-ID: <20251206004550.GA3300344@bhelgaas> (raw)
In-Reply-To: <20251104001001.3833651-3-terry.bowman@amd.com>
On Mon, Nov 03, 2025 at 06:09:38PM -0600, Terry Bowman wrote:
> CXL and AER drivers need the ability to identify CXL devices.
>
> Introduce set_pcie_cxl() with logic checking for CXL.mem or CXL.cache
> status in the CXL Flexbus DVSEC status register. The CXL Flexbus DVSEC
> presence is used because it is required for all the CXL PCIe devices.[1]
>
> Add boolean 'struct pci_dev::is_cxl' with the purpose to cache the CXL
> CXL.cache and CXl.mem status.
>
> In the case the device is an EP or USP, call set_pcie_cxl() on behalf of
> the parent downstream device. Once a device is created there is
> possibilty the parent training or CXL state was updated as well. This
> will make certain the correct parent CXL state is cached.
See question at comment below.
s/on behalf of the parent downstream device/for the parent bridge/
s/possibilty/possibility/
> +++ b/drivers/pci/probe.c
> @@ -1709,6 +1709,33 @@ static void set_pcie_thunderbolt(struct pci_dev *dev)
> dev->is_thunderbolt = 1;
> }
>
> +static void set_pcie_cxl(struct pci_dev *dev)
> +{
> + struct pci_dev *parent;
> + u16 dvsec = pci_find_dvsec_capability(dev, PCI_VENDOR_ID_CXL,
> + PCI_DVSEC_CXL_FLEXBUS_PORT);
> + if (dvsec) {
> + u16 cap;
> +
> + pci_read_config_word(dev, dvsec + PCI_DVSEC_CXL_FLEXBUS_STATUS_OFFSET, &cap);
> +
> + dev->is_cxl = FIELD_GET(PCI_DVSEC_CXL_FLEXBUS_STATUS_CACHE_MASK, cap) ||
> + FIELD_GET(PCI_DVSEC_CXL_FLEXBUS_STATUS_MEM_MASK, cap);
Wrap to fit in 80 columns like the rest of the file.
Not sure the "_MASK" and "_OFFSET" on the end of all these #defines is
really needed. Other items in pci_regs.h typically don't include
them, and these names get really long.
> + }
> +
> + if (!pci_is_pcie(dev) ||
> + !(pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT ||
> + pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM))
> + return;
Maybe could do the pci_is_pcie() check first, before the
pci_find_dvsec_capability(), so we could avoid that search, e.g.,
if (!pci_is_pcie(dev))
return;
dvsec = pci_find_dvsec_capability(dev, PCI_VENDOR_ID_CXL, ...);
> + /*
> + * Update parent's CXL state because alternate protocol training
> + * may have changed
What is the event that changes alternate protocol training? The
commit log says "once a device is created", but I don't know what that
means in terms of hardware.
> + */
> + parent = pci_upstream_bridge(dev);
> + set_pcie_cxl(parent);
> +}
next prev parent reply other threads:[~2025-12-06 0:45 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-04 0:09 [PATCH v13 00/25] Enable CXL PCIe Port Protocol Error handling and logging Terry Bowman
2025-11-04 0:09 ` [PATCH v13 01/25] CXL/PCI: Move CXL DVSEC definitions into uapi/linux/pci_regs.h Terry Bowman
2025-12-06 0:31 ` Bjorn Helgaas
2025-12-06 0:41 ` dan.j.williams
2025-12-06 1:56 ` Bjorn Helgaas
2025-12-06 4:56 ` dan.j.williams
2025-11-04 0:09 ` [PATCH v13 02/25] PCI/CXL: Introduce pcie_is_cxl() Terry Bowman
2025-12-06 0:45 ` Bjorn Helgaas [this message]
2025-12-08 15:26 ` Bowman, Terry
2025-12-08 18:33 ` Bjorn Helgaas
2025-11-04 0:09 ` [PATCH v13 03/25] cxl/pci: Remove unnecessary CXL Endpoint handling helper functions Terry Bowman
2025-11-04 0:09 ` [PATCH v13 04/25] cxl/pci: Remove unnecessary CXL RCH " Terry Bowman
2025-11-04 0:09 ` [PATCH v13 05/25] cxl: Remove CXL VH handling in CONFIG_PCIEAER_CXL conditional blocks from core/pci.c Terry Bowman
2025-11-04 0:09 ` [PATCH v13 06/25] cxl: Move CXL driver's RCH error handling into core/ras_rch.c Terry Bowman
2025-11-04 0:09 ` [PATCH v13 07/25] CXL/AER: Replace device_lock() in cxl_rch_handle_error_iter() with guard() lock Terry Bowman
2025-12-08 18:05 ` Bjorn Helgaas
2025-11-04 0:09 ` [PATCH v13 08/25] CXL/AER: Move AER drivers RCH error handling into pcie/aer_cxl_rch.c Terry Bowman
2025-12-08 18:06 ` Bjorn Helgaas
2025-12-08 21:28 ` Bowman, Terry
2025-12-10 21:57 ` Bowman, Terry
2025-12-10 23:12 ` Bjorn Helgaas
2025-11-04 0:09 ` [PATCH v13 09/25] PCI/AER: Report CXL or PCIe bus error type in trace logging Terry Bowman
2025-11-04 0:09 ` [PATCH v13 10/25] cxl/pci: Update RAS handler interfaces to also support CXL Ports Terry Bowman
2025-11-04 0:09 ` [PATCH v13 11/25] cxl/pci: Log message if RAS registers are unmapped Terry Bowman
2025-11-04 0:09 ` [PATCH v13 12/25] cxl/pci: Unify CXL trace logging for CXL Endpoints and CXL Ports Terry Bowman
2025-11-04 0:09 ` [PATCH v13 13/25] cxl/pci: Update cxl_handle_cor_ras() to return early if no RAS errors Terry Bowman
2025-11-04 0:09 ` [PATCH v13 14/25] cxl/pci: Map CXL Endpoint Port and CXL Switch Port RAS registers Terry Bowman
2025-11-04 0:09 ` [PATCH v13 15/25] CXL/PCI: Introduce PCI_ERS_RESULT_PANIC Terry Bowman
2025-11-04 0:09 ` [PATCH v13 16/25] CXL/AER: Introduce pcie/aer_cxl_vh.c in AER driver for forwarding CXL errors Terry Bowman
2025-12-08 18:36 ` Bjorn Helgaas
2025-11-04 0:09 ` [PATCH v13 17/25] cxl: Introduce cxl_pci_drv_bound() to check for bound driver Terry Bowman
2025-11-04 0:09 ` [PATCH v13 18/25] cxl: Change CXL handlers to use guard() instead of scoped_guard() Terry Bowman
2025-11-04 0:09 ` [PATCH v13 19/25] cxl/pci: Introduce CXL protocol error handlers for Endpoints Terry Bowman
2025-11-04 0:09 ` [PATCH v13 20/25] CXL/PCI: Introduce CXL Port protocol error handlers Terry Bowman
2025-12-08 18:37 ` Bjorn Helgaas
2025-12-09 15:17 ` Bowman, Terry
2025-11-04 0:09 ` [PATCH v13 21/25] PCI/AER: Dequeue forwarded CXL error Terry Bowman
2025-11-04 0:09 ` [PATCH v13 22/25] CXL/PCI: Export and rename merge_result() to pci_ers_merge_result() Terry Bowman
2025-12-08 18:38 ` Bjorn Helgaas
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