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GET /api/1.0/patches/2198049/?format=api
{ "id": 2198049, "url": "http://patchwork.ozlabs.org/api/1.0/patches/2198049/?format=api", "project": { "id": 28, "url": "http://patchwork.ozlabs.org/api/1.0/projects/28/?format=api", "name": "Linux PCI development", "link_name": "linux-pci", "list_id": "linux-pci.vger.kernel.org", "list_email": "linux-pci@vger.kernel.org", "web_url": null, "scm_url": null, "webscm_url": null }, "msgid": "<20260219081318.4156901-8-den@valinux.co.jp>", "date": "2026-02-19T08:13:18", "name": "[v9,7/7] PCI: endpoint: pci-ep-msi: Add embedded doorbell fallback", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "6b949ed2cf35b226f1c69a14fa384713b805cda8", "submitter": { "id": 91573, "url": "http://patchwork.ozlabs.org/api/1.0/people/91573/?format=api", "name": "Koichiro Den", "email": "den@valinux.co.jp" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-pci/patch/20260219081318.4156901-8-den@valinux.co.jp/mbox/", "series": [ { "id": 492647, "url": "http://patchwork.ozlabs.org/api/1.0/series/492647/?format=api", "date": "2026-02-19T08:13:11", "name": "PCI: endpoint: pci-ep-msi: Add embedded doorbell fallback", "version": 9, "mbox": "http://patchwork.ozlabs.org/series/492647/mbox/" } ], "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2198049/checks/", "tags": {}, "headers": { "Return-Path": "\n <linux-pci+bounces-47618-incoming=patchwork.ozlabs.org@vger.kernel.org>", "X-Original-To": [ "incoming@patchwork.ozlabs.org", "linux-pci@vger.kernel.org" ], "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=valinux.co.jp header.i=@valinux.co.jp\n header.a=rsa-sha256 header.s=selector1 header.b=gakf4MSo;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.234.253.10; helo=sea.lore.kernel.org;\n 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bh=rN0/TQ7jIIzGySPJfgpzE9PVGjocPXJa/8Wx7UgygPk=;\n b=gakf4MSooWyxZ6UI6HJr2BWt+Z/RG7RgV0FEdj02J0jEVsckcLryADcQ2M/BJ+Za2p/a0JWU1h7RThdXE/tJibLuUnl90TYCMlUkHpifl/CopzBx00ejeCxK/T+Vs1UezsBOB8chIgMJpU47d2zVOuJCBDlxzfS72DXbkhzW7BQ=", "From": "Koichiro Den <den@valinux.co.jp>", "To": "jingoohan1@gmail.com,\n\tmani@kernel.org,\n\tlpieralisi@kernel.org,\n\tkwilczynski@kernel.org,\n\trobh@kernel.org,\n\tbhelgaas@google.com,\n\tkishon@kernel.org,\n\tjdmason@kudzu.us,\n\tdave.jiang@intel.com,\n\tallenbh@gmail.com,\n\tcassel@kernel.org,\n\tFrank.Li@nxp.com,\n\tshinichiro.kawasaki@wdc.com,\n\tchristian.bruel@foss.st.com", "Cc": "mmaddireddy@nvidia.com,\n\tlinux-pci@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org,\n\tntb@lists.linux.dev", "Subject": "[PATCH v9 7/7] PCI: endpoint: pci-ep-msi: Add embedded doorbell\n fallback", "Date": "Thu, 19 Feb 2026 17:13:18 +0900", "Message-ID": "<20260219081318.4156901-8-den@valinux.co.jp>", "X-Mailer": "git-send-email 2.51.0", "In-Reply-To": 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", "X-OriginatorOrg": "valinux.co.jp", "X-MS-Exchange-CrossTenant-Network-Message-Id": "\n 43979eac-d5d5-4223-c599-08de6f8ec279", "X-MS-Exchange-CrossTenant-AuthSource": "TY7P286MB7722.JPNP286.PROD.OUTLOOK.COM", "X-MS-Exchange-CrossTenant-AuthAs": "Internal", "X-MS-Exchange-CrossTenant-OriginalArrivalTime": "19 Feb 2026 08:13:27.2610\n (UTC)", "X-MS-Exchange-CrossTenant-FromEntityHeader": "Hosted", "X-MS-Exchange-CrossTenant-Id": "7a57bee8-f73d-4c5f-a4f7-d72c91c8c111", "X-MS-Exchange-CrossTenant-MailboxType": "HOSTED", "X-MS-Exchange-CrossTenant-UserPrincipalName": "\n gEmq0Vn6pELilKFedxvSljyNTPJYZDWR8NzoNMyy7SXHBaaCAcPcTqJSqpglIkbM89WzYWMl/orHVFLrsVZ6qA==", "X-MS-Exchange-Transport-CrossTenantHeadersStamped": "OSOP286MB4397" }, "content": "Some endpoint platforms cannot use platform MSI / GIC ITS to implement\nEP-side doorbells. In those cases, EPF drivers cannot provide an\ninterrupt-driven doorbell and often fall back to polling.\n\nAdd an \"embedded\" doorbell backend that uses a controller-integrated\ndoorbell target (e.g. DesignWare integrated eDMA interrupt-emulation\ndoorbell).\n\nThe backend locates the doorbell register and a corresponding Linux IRQ\nvia the EPC aux-resource API. If the doorbell register is already\nexposed via a fixed BAR mapping, provide BAR+offset. Otherwise provide\nthe physical address so EPF drivers can map it into BAR space.\n\nWhen MSI doorbell allocation fails with -ENODEV,\npci_epf_alloc_doorbell() falls back to this embedded backend.\n\nSigned-off-by: Koichiro Den <den@valinux.co.jp>\n---\nChanges since v8:\n - Add MMIO address alignment check\n - Drop 'eDMA' word from the subject\n\n drivers/pci/endpoint/pci-ep-msi.c | 99 ++++++++++++++++++++++++++++++-\n 1 file changed, 97 insertions(+), 2 deletions(-)", "diff": "diff --git a/drivers/pci/endpoint/pci-ep-msi.c b/drivers/pci/endpoint/pci-ep-msi.c\nindex 50badffa9d72..f287fbf684ca 100644\n--- a/drivers/pci/endpoint/pci-ep-msi.c\n+++ b/drivers/pci/endpoint/pci-ep-msi.c\n@@ -6,6 +6,8 @@\n * Author: Frank Li <Frank.Li@nxp.com>\n */\n \n+#include <linux/align.h>\n+#include <linux/cleanup.h>\n #include <linux/device.h>\n #include <linux/export.h>\n #include <linux/interrupt.h>\n@@ -36,6 +38,86 @@ static void pci_epf_write_msi_msg(struct msi_desc *desc, struct msi_msg *msg)\n \tpci_epc_put(epc);\n }\n \n+static int pci_epf_alloc_doorbell_embedded(struct pci_epf *epf, u16 num_db)\n+{\n+\tconst struct pci_epc_aux_resource *doorbell = NULL;\n+\tstruct pci_epf_doorbell_msg *msg;\n+\tstruct pci_epc *epc = epf->epc;\n+\tstruct device *dev = &epf->dev;\n+\tint count, ret, i;\n+\tu64 addr;\n+\n+\tcount = pci_epc_get_aux_resources(epc, epf->func_no, epf->vfunc_no,\n+\t\t\t\t\t NULL, 0);\n+\tif (count == -EOPNOTSUPP || count == 0)\n+\t\treturn -ENODEV;\n+\tif (count < 0)\n+\t\treturn count;\n+\n+\tstruct pci_epc_aux_resource *res __free(kfree) =\n+\t\t\t\tkcalloc(count, sizeof(*res), GFP_KERNEL);\n+\tif (!res)\n+\t\treturn -ENOMEM;\n+\n+\tret = pci_epc_get_aux_resources(epc, epf->func_no, epf->vfunc_no,\n+\t\t\t\t\tres, count);\n+\tif (ret == -EOPNOTSUPP || ret == 0)\n+\t\treturn -ENODEV;\n+\tif (ret < 0)\n+\t\treturn ret;\n+\n+\tcount = ret;\n+\n+\tfor (i = 0; i < count; i++) {\n+\t\tif (res[i].type == PCI_EPC_AUX_DOORBELL_MMIO) {\n+\t\t\tif (doorbell) {\n+\t\t\t\tdev_warn(dev,\n+\t\t\t\t\t \"Duplicate DOORBELL_MMIO resource found\\n\");\n+\t\t\t\tcontinue;\n+\t\t\t}\n+\t\t\tdoorbell = &res[i];\n+\t\t}\n+\t}\n+\tif (!doorbell)\n+\t\treturn -ENODEV;\n+\n+\taddr = doorbell->phys_addr;\n+\tif (!IS_ALIGNED(addr, sizeof(u32)))\n+\t\treturn -EINVAL;\n+\n+\tmsg = kcalloc(num_db, sizeof(*msg), GFP_KERNEL);\n+\tif (!msg)\n+\t\treturn -ENOMEM;\n+\n+\t/*\n+\t * Embedded doorbell backends (e.g. DesignWare eDMA interrupt emulation)\n+\t * typically provide a single IRQ and do not offer per-doorbell\n+\t * distinguishable address/data pairs. The EPC aux resource therefore\n+\t * exposes one DOORBELL_MMIO entry (u.db_mmio.irq).\n+\t *\n+\t * Still, pci_epf_alloc_doorbell() allows requesting multiple doorbells.\n+\t * For such backends we replicate the same address/data for each entry\n+\t * and mark the IRQ as shared (IRQF_SHARED). Consumers must treat them\n+\t * as equivalent \"kick\" doorbells.\n+\t */\n+\tfor (i = 0; i < num_db; i++)\n+\t\tmsg[i] = (struct pci_epf_doorbell_msg) {\n+\t\t\t.msg.address_lo = (u32)addr,\n+\t\t\t.msg.address_hi = (u32)(addr >> 32),\n+\t\t\t.msg.data = doorbell->u.db_mmio.data,\n+\t\t\t.virq = doorbell->u.db_mmio.irq,\n+\t\t\t.irq_flags = IRQF_SHARED,\n+\t\t\t.type = PCI_EPF_DOORBELL_EMBEDDED,\n+\t\t\t.bar = doorbell->bar,\n+\t\t\t.offset = (doorbell->bar == NO_BAR) ? 0 :\n+\t\t\t\t doorbell->bar_offset,\n+\t\t};\n+\n+\tepf->num_db = num_db;\n+\tepf->db_msg = msg;\n+\treturn 0;\n+}\n+\n static int pci_epf_alloc_doorbell_msi(struct pci_epf *epf, u16 num_db)\n {\n \tstruct pci_epf_doorbell_msg *msg;\n@@ -109,8 +191,21 @@ int pci_epf_alloc_doorbell(struct pci_epf *epf, u16 num_db)\n \tif (!ret)\n \t\treturn 0;\n \n-\tdev_err(dev, \"Failed to allocate doorbell: %d\\n\", ret);\n-\treturn ret;\n+\t/*\n+\t * Fall back to embedded doorbell only when platform MSI is unavailable\n+\t * for this EPC.\n+\t */\n+\tif (ret != -ENODEV)\n+\t\treturn ret;\n+\n+\tret = pci_epf_alloc_doorbell_embedded(epf, num_db);\n+\tif (ret) {\n+\t\tdev_err(dev, \"Failed to allocate doorbell: %d\\n\", ret);\n+\t\treturn ret;\n+\t}\n+\n+\tdev_info(dev, \"Using embedded (DMA) doorbell fallback\\n\");\n+\treturn 0;\n }\n EXPORT_SYMBOL_GPL(pci_epf_alloc_doorbell);\n \n", "prefixes": [ "v9", "7/7" ] }