linux-kernel - [tip: irq/msi] drm/radeon: Make MSI address limit based on the device DMA limit

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Message-ID: <176981869569.2495410.10603060915971455685.tip-bot2@tip-bot2>
Date: Sat, 31 Jan 2026 00:18:15 -0000
From: "tip-bot2 for Vivian Wang" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Vivian Wang <wangruikang@...as.ac.cn>, Thomas Gleixner <tglx@...nel.org>,
 christian.koenig@....com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: irq/msi] drm/radeon: Make MSI address limit based on the device
 DMA limit

The following commit has been merged into the irq/msi branch of tip:

Commit-ID:     617562bbe12df796fc21df5fbf262eadf083a90f
Gitweb:        https://git.kernel.org/tip/617562bbe12df796fc21df5fbf262eadf083a90f
Author:        Vivian Wang <wangruikang@...as.ac.cn>
AuthorDate:    Thu, 29 Jan 2026 09:56:08 +08:00
Committer:     Thomas Gleixner <tglx@...nel.org>
CommitterDate: Sat, 31 Jan 2026 01:11:48 +01:00

drm/radeon: Make MSI address limit based on the device DMA limit

The radeon driver restricts the MSI message address for devices older than
the BONAIR generation to 32-bit MSI addresses due to the former
restrictions of the PCI/MSI code which only allowed either 32-bit or full
64-bit address range.

This does not work on platforms which have a MSI doorbell address above the
32-bit boundary but do not support the full 64 bit address range.

The PCI/MSI core converted this binary decision to a DMA_BIT_MASK() based
decision, which allows to describe the device limitations precisely.

Convert the driver to provide the exact DMA address limitations to the
PCI/MSI core. That allows devices which do not support the full 64-bit
address space to work on platforms which have a MSI doorbell address above
the 32-bit limit as long as it is within the hardware's addressable range.

[ tglx: Massage changelog ]

Signed-off-by: Vivian Wang <wangruikang@...as.ac.cn>
Signed-off-by: Thomas Gleixner <tglx@...nel.org>
Reviewed-by: Christian König <christian.koenig@....com>
Link: https://patch.msgid.link/20260129-pci-msi-addr-mask-v4-3-70da998f2750@iscas.ac.cn
---
 drivers/gpu/drm/radeon/radeon_device.c  |  1 +
 drivers/gpu/drm/radeon/radeon_irq_kms.c | 10 ----------
 2 files changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 60afaa8..5faae03 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1374,6 +1374,7 @@ int radeon_device_init(struct radeon_device *rdev,
 		pr_warn("radeon: No suitable DMA available\n");
 		return r;
 	}
+	rdev->pdev->msi_addr_mask = DMA_BIT_MASK(dma_bits);
 	rdev->need_swiotlb = drm_need_swiotlb(dma_bits);
 
 	/* Registers mapping */
diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c
index d550554..839d619 100644
--- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
@@ -245,16 +245,6 @@ static bool radeon_msi_ok(struct radeon_device *rdev)
 	if (rdev->flags & RADEON_IS_AGP)
 		return false;
 
-	/*
-	 * Older chips have a HW limitation, they can only generate 40 bits
-	 * of address for "64-bit" MSIs which breaks on some platforms, notably
-	 * IBM POWER servers, so we limit them
-	 */
-	if (rdev->family < CHIP_BONAIRE) {
-		dev_info(rdev->dev, "radeon: MSI limited to 32-bit\n");
-		rdev->pdev->msi_addr_mask = DMA_BIT_MASK(32);
-	}
-
 	/* force MSI on */
 	if (radeon_msi == 1)
 		return true;