Linux PCI subsystem development
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From: Vidya Sagar <vidyas@nvidia.com>
To: <bhelgaas@google.com>
Cc: <vsethi@nvidia.com>, <sdonthineni@nvidia.com>,
	<kthota@nvidia.com>, <mmaddireddy@nvidia.com>,
	<kumarahul@nvidia.com>, <sagar.tv@gmail.com>,
	<linux-pci@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	Vidya Sagar <vidyas@nvidia.com>
Subject: [PATCH V3 1/5] PCI: Add DEV3 14-Bit Tag Requester register definitions
Date: Sat, 15 Aug 2026 01:46:17 +0530	[thread overview]
Message-ID: <20260814201621.2281245-2-vidyas@nvidia.com> (raw)
In-Reply-To: <20260814201621.2281245-1-vidyas@nvidia.com>

The Device 3 Extended Capability advertises 14-Bit Tag Requester support
in bit 2 of the Device 3 Capabilities register and carries the matching
enable in bit 2 of the Device 3 Control register.  Only the register
offsets and DEV3_STA.Segment Captured are defined today.

Add both 14-Bit Tag Requester bit definitions.  There is deliberately no
completer counterpart: a completer reflects the Tag field of the request
it answers, so the spec defines a 14-Bit Tag Completer Supported bit but
no completer enable, and software has nothing to program there.

No functional change.

Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
---
V3:
* No change

V2:
* New patch as a result of splitting the V1 monolithic patch

 include/uapi/linux/pci_regs.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index facaa324bd86..b2ba5c2642f0 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -1254,7 +1254,9 @@
 
 /* Device 3 Extended Capability */
 #define PCI_DEV3_CAP		0x04	/* Device 3 Capabilities Register */
+#define  PCI_DEV3_CAP_14BIT_TAG_REQ	0x00000004 /* 14-Bit Tag Requester Supported */
 #define PCI_DEV3_CTL		0x08	/* Device 3 Control Register */
+#define  PCI_DEV3_CTL_14BIT_TAG_REQ_EN	0x00000004 /* 14-Bit Tag Requester Enable */
 #define PCI_DEV3_STA		0x0c	/* Device 3 Status Register */
 #define  PCI_DEV3_STA_SEGMENT	0x8	/* Segment Captured (end-to-end flit-mode detected) */
 
-- 
2.43.0


  reply	other threads:[~2026-08-14 20:17 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-08-14 20:16 [PATCH V3 0/5] PCI: Re-evaluate DEV3 14-Bit Tag Requester Enable on link mode changes Vidya Sagar
2026-08-14 20:16 ` Vidya Sagar [this message]
2026-08-14 20:19   ` [PATCH V3 1/5] PCI: Add DEV3 14-Bit Tag Requester register definitions sashiko-bot
2026-08-14 20:16 ` [PATCH V3 2/5] PCI: Move __pcie_update_link_speed() out of line Vidya Sagar
2026-08-14 20:31   ` sashiko-bot
2026-08-14 20:16 ` [PATCH V3 3/5] PCI: Save and restore the Device 3 Control register Vidya Sagar
2026-08-14 20:28   ` sashiko-bot
2026-08-14 20:16 ` [PATCH V3 4/5] PCI: Clear stale 14-Bit Tag Requester Enable when a link leaves Flit Mode Vidya Sagar
2026-08-14 20:34   ` sashiko-bot
2026-08-14 20:16 ` [PATCH V3 5/5] PCI: pciehp: Clear stale 14-Bit Tag Requester Enable on hot add Vidya Sagar
2026-08-14 20:34   ` sashiko-bot

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