From: Koichiro Den <den@valinux.co.jp>
To: "Jon Mason" <jdmason@kudzu.us>,
"Dave Jiang" <dave.jiang@intel.com>,
"Allen Hubbe" <allenbh@gmail.com>,
"Manivannan Sadhasivam" <mani@kernel.org>,
"Krzysztof Wilczyński" <kwilczynski@kernel.org>,
"Kishon Vijay Abraham I" <kishon@kernel.org>,
"Bjorn Helgaas" <bhelgaas@google.com>,
"Frank Li" <Frank.Li@nxp.com>,
"Jerome Brunet" <jbrunet@baylibre.com>,
"Lorenzo Pieralisi" <lpieralisi@kernel.org>,
"Niklas Cassel" <cassel@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
ntb@lists.linux.dev
Subject: [PATCH v4 03/12] PCI: endpoint: pci-epf-vntb: Report 0-based doorbell vector via ntb_db_event()
Date: Wed, 13 May 2026 11:49:14 +0900 [thread overview]
Message-ID: <20260513024923.451765-4-den@valinux.co.jp> (raw)
In-Reply-To: <20260513024923.451765-1-den@valinux.co.jp>
ntb_db_event() expects the vector number to be relative to the first
doorbell vector starting at 0.
pci-epf-vntb reserves vector 0 for link events and uses higher vector
indices for doorbells. By passing the raw slot index to ntb_db_event(),
it effectively assumes that doorbell 0 maps to vector 1.
However, because the host uses a legacy slot layout and writes doorbell
0 into the third slot, doorbell 0 ultimately appears as vector 2 from
the NTB core perspective.
Adjust pci-epf-vntb to:
- skip the unused second slot, and
- report doorbells as 0-based vectors (DB#0 -> vector 0).
This change does not introduce a behavioral difference until
.db_vector_count()/.db_vector_mask() are implemented, because without
those callbacks NTB clients effectively ignore the vector number.
Fixes: e35f56bb0330 ("PCI: endpoint: Support NTB transfer between RC and EP")
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
Changes since v3:
- Use EPF_IRQ_DB_START instead of a literal offset in deferred MSI handling.
drivers/pci/endpoint/functions/pci-epf-vntb.c | 25 ++++++++++++-------
1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index cc0b356973f3..d31e2eee0869 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -83,6 +83,12 @@ enum epf_ntb_bar {
VNTB_BAR_NUM,
};
+enum epf_irq_slot {
+ EPF_IRQ_LINK = 0,
+ EPF_IRQ_RESERVED_DB, /* Historically skipped slot */
+ EPF_IRQ_DB_START,
+};
+
/*
* +--------------------------------------------------+ Base
* | |
@@ -272,10 +278,11 @@ static void epf_ntb_cmd_handler(struct work_struct *work)
ntb = container_of(work, struct epf_ntb, cmd_handler.work);
- for (i = 1; i < ntb->db_count && !ntb->msi_doorbell; i++) {
+ for (i = EPF_IRQ_DB_START; i < ntb->db_count && !ntb->msi_doorbell;
+ i++) {
if (ntb->epf_db[i]) {
- atomic64_or(1 << (i - 1), &ntb->db);
- ntb_db_event(&ntb->ntb, i);
+ atomic64_or(1 << (i - EPF_IRQ_DB_START), &ntb->db);
+ ntb_db_event(&ntb->ntb, i - EPF_IRQ_DB_START);
ntb->epf_db[i] = 0;
}
}
@@ -341,10 +348,10 @@ static irqreturn_t epf_ntb_doorbell_handler(int irq, void *data)
struct epf_ntb *ntb = data;
int i;
- for (i = 1; i < ntb->db_count; i++)
+ for (i = EPF_IRQ_DB_START; i < ntb->db_count; i++)
if (irq == ntb->epf->db_msg[i].virq) {
- atomic64_or(1 << (i - 1), &ntb->db);
- ntb_db_event(&ntb->ntb, i);
+ atomic64_or(1 << (i - EPF_IRQ_DB_START), &ntb->db);
+ ntb_db_event(&ntb->ntb, i - EPF_IRQ_DB_START);
}
return IRQ_HANDLED;
@@ -1450,8 +1457,8 @@ static void vntb_epf_peer_db_work(struct work_struct *work)
while (db_bits) {
/*
* pci_epc_raise_irq() for MSI expects a 1-based
- * interrupt number. db_bit is zero-based, so add 3 to
- * preserve the historical slot offset.
+ * interrupt number. The first usable doorbell starts
+ * at EPF_IRQ_DB_START in the legacy slot layout.
*
* Legacy mapping (kept for compatibility):
*
@@ -1465,7 +1472,7 @@ static void vntb_epf_peer_db_work(struct work_struct *work)
* interoperability with older peers.
*/
db_bit = __ffs64(db_bits);
- interrupt_num = db_bit + 3;
+ interrupt_num = db_bit + EPF_IRQ_DB_START + 1;
db_bits &= ~BIT_ULL(db_bit);
ret = pci_epc_raise_irq(epf->epc, func_no, vfunc_no,
--
2.51.0
next prev parent reply other threads:[~2026-05-13 2:49 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-13 2:49 [PATCH v4 00/12] PCI: endpoint: pci-epf-vntb / NTB: epf: Enable per-doorbell bit handling Koichiro Den
2026-05-13 2:49 ` [PATCH v4 01/12] PCI: endpoint: pci-epf-vntb: Document legacy MSI doorbell offset Koichiro Den
2026-05-13 2:49 ` [PATCH v4 02/12] PCI: endpoint: pci-epf-vntb: Defer pci_epc_raise_irq() out of atomic context Koichiro Den
2026-05-14 18:53 ` Frank Li
2026-05-13 2:49 ` Koichiro Den [this message]
2026-05-13 2:49 ` [PATCH v4 04/12] PCI: endpoint: pci-epf-vntb: Reject unusable doorbell counts Koichiro Den
2026-05-14 18:55 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 05/12] PCI: endpoint: pci-epf-vntb: Guard configfs writes after EPC attach Koichiro Den
2026-05-14 18:57 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 06/12] PCI: endpoint: pci-epf-vntb: Exclude reserved slots from db_valid_mask Koichiro Den
2026-05-13 2:49 ` [PATCH v4 07/12] PCI: endpoint: pci-epf-vntb: Implement db_vector_count/mask for doorbells Koichiro Den
2026-05-14 19:02 ` Frank Li
2026-05-13 2:49 ` [PATCH v4 08/12] NTB: epf: Document legacy doorbell slot offset in ntb_epf_peer_db_set() Koichiro Den
2026-05-13 2:49 ` [PATCH v4 09/12] NTB: epf: Make db_valid_mask cover only real doorbell bits Koichiro Den
2026-05-26 22:21 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 10/12] NTB: epf: Report 0-based doorbell vector via ntb_db_event() Koichiro Den
2026-05-14 19:03 ` Frank Li
2026-05-26 22:28 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 11/12] NTB: epf: Fix doorbell bitmask and IRQ vector handling Koichiro Den
2026-05-14 19:06 ` Frank Li
2026-05-26 22:36 ` Dave Jiang
2026-05-13 2:49 ` [PATCH v4 12/12] NTB: epf: Implement db_vector_count/mask for doorbells Koichiro Den
2026-05-26 22:47 ` Dave Jiang
2026-06-23 16:31 ` Bjorn Helgaas
2026-06-24 1:35 ` Koichiro Den
2026-05-19 14:42 ` [PATCH v4 00/12] PCI: endpoint: pci-epf-vntb / NTB: epf: Enable per-doorbell bit handling Manivannan Sadhasivam
2026-05-19 21:29 ` Dave Jiang
2026-05-21 6:29 ` Koichiro Den
2026-05-26 14:45 ` Dave Jiang
2026-05-26 15:56 ` Koichiro Den
2026-05-26 16:27 ` Dave Jiang
2026-05-27 9:09 ` Manivannan Sadhasivam
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260513024923.451765-4-den@valinux.co.jp \
--to=den@valinux.co.jp \
--cc=Frank.Li@nxp.com \
--cc=allenbh@gmail.com \
--cc=bhelgaas@google.com \
--cc=cassel@kernel.org \
--cc=dave.jiang@intel.com \
--cc=jbrunet@baylibre.com \
--cc=jdmason@kudzu.us \
--cc=kishon@kernel.org \
--cc=kwilczynski@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lpieralisi@kernel.org \
--cc=mani@kernel.org \
--cc=ntb@lists.linux.dev \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).