linux-kernel - Re: [PATCH v4 3/4] drm/radeon: Raise msi_addr_mask to dma

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Message-ID: <f7c23358-9438-47cd-8493-6bc84ecd9900@amd.com>
Date: Thu, 29 Jan 2026 09:08:00 +0100
From: Christian König <christian.koenig@....com>
To: Vivian Wang <wangruikang@...as.ac.cn>,
 Madhavan Srinivasan <maddy@...ux.ibm.com>,
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
 "Christophe Leroy (CS GROUP)" <chleroy@...nel.org>,
 Alex Deucher <alexander.deucher@....com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Bjorn Helgaas <bhelgaas@...gle.com>, Jaroslav Kysela <perex@...ex.cz>,
 Takashi Iwai <tiwai@...e.com>, Brett Creeley <brett.creeley@....com>
Cc: Han Gao <gaohan@...as.ac.cn>, Thomas Gleixner <tglx@...nel.org>,
 linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
 amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
 netdev@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-sound@...r.kernel.org, linux-riscv@...ts.infradead.org,
 sophgo@...ts.linux.dev
Subject: Re: [PATCH v4 3/4] drm/radeon: Raise msi_addr_mask to dma_bits

On 1/29/26 02:56, Vivian Wang wrote:
> The code was originally written using no_64bit_msi, which restricts the
> device to 32-bit MSI addresses.
> 
> Since msi_addr_mask is introduced, use DMA_BIT_MASK(dma_bits) instead of
> DMA_BIT_MASK(32) here for msi_addr_mask, describing the restriction more
> precisely and allowing these devices to work on platforms with MSI
> doorbell address above the 32-bit limit, as long as it is within the
> hardware's addressable range.
> 
> Signed-off-by: Vivian Wang <wangruikang@...as.ac.cn>

Reviewed-by: Christian König <christian.koenig@....com>

> 
> ---
> v4: Patch message rewording for more consistency
> ---
>  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 60afaa8e56b4..5faae0361361 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 d550554a6f3f..839d619e5602 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;
>