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PCI: endpoint: pci-epf-vntb: Report 0-based doorbell vector via ntb_db_event()

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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: e35f56bb03 ("PCI: endpoint: Support NTB transfer between RC and EP")
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260513024923.451765-4-den@valinux.co.jp
This commit is contained in:
Koichiro Den 2026-05-13 11:49:14 +09:00 committed by Bjorn Helgaas
parent 18355c1e98
commit 91fb4488cd
1 changed files with 16 additions and 9 deletions
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25
drivers/pci/endpoint/functions/pci-epf-vntb.c
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@ -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,