git: 82281715ef2f - main - puc: be more careful about using MSI

The branch main has been updated by nprice:

URL: https://cgit.FreeBSD.org/src/commit/?id=82281715ef2f08f873a19340c3d00ef7fa9bf728

commit 82281715ef2f08f873a19340c3d00ef7fa9bf728
Author:     Nick Price <nprice@FreeBSD.org>
AuthorDate: 2026-09-12 21:58:10 +0000
Commit:     Nick Price <nprice@FreeBSD.org>
CommitDate: 2026-09-12 21:58:16 +0000

    puc: be more careful about using MSI
    
    puc has preferred MSI for every card since MSI support was added, with
    only a global tunable to opt out.  uart(4) makes the same decision for
    the serial devices it attaches directly, and has since grown two
    defences: it skips MSI unless the device advertises exactly one vector,
    because attaching a single instance to a device offering many has caused
    problems (PR 235016), and it lets individual devices be flagged when
    they claim MSI support that does not work.
    
    Adopt both.
    
    Approved by:    adrian (mentor)
    Reviewed by:    adrian
    Differential Revision:  https://reviews.freebsd.org/D59623
    
    Signed-off-by: Nick Price <nprice@FreeBSD.org>
---
 sys/dev/puc/puc_cfg.h | 4 ++++
 sys/dev/puc/puc_pci.c | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/sys/dev/puc/puc_cfg.h b/sys/dev/puc/puc_cfg.h
index 962ab86fe6d3..7c6aa74a427a 100644
--- a/sys/dev/puc/puc_cfg.h
+++ b/sys/dev/puc/puc_cfg.h
@@ -52,6 +52,9 @@
 #define PUC_ILR_DIGI		1
 #define PUC_ILR_QUATECH		2
 
+/* Configuration flags. */
+#define	PUC_FLAGS_NO_MSI	0x01
+
 /* Configuration queries. */
 enum puc_cfg_cmd {
 	PUC_CFG_GET_CLOCK,
@@ -80,6 +83,7 @@ struct puc_cfg {
 	int8_t		rid;		/* Rid of first port */
 	int8_t		d_rid;		/* Delta rid of next ports */
 	int8_t		d_ofs;		/* Delta offset of next ports */
+	uint8_t		flags;		/* PUC_FLAGS_* */
 	puc_config_f 	*config_function;
 };
 
diff --git a/sys/dev/puc/puc_pci.c b/sys/dev/puc/puc_pci.c
index 9709a606fb44..a15b6f643fb2 100644
--- a/sys/dev/puc/puc_pci.c
+++ b/sys/dev/puc/puc_pci.c
@@ -133,7 +133,9 @@ puc_pci_attach(device_t dev)
 
 	sc = device_get_softc(dev);
 
-	if (!puc_msi_disable) {
+	if (!puc_msi_disable &&
+	    (sc->sc_cfg->flags & PUC_FLAGS_NO_MSI) == 0 &&
+	    pci_msi_count(dev) == 1) {
 		count = 1;
 
 		if (pci_alloc_msi(dev, &count) == 0) {