From: "Christian König" <christian.koenig@amd.com>
To: Huang Rui <ray.huang@amd.com>, Sinan Kaya <okaya@codeaurora.org>
Cc: "Tom St Denis" <tom.stdenis@amd.com>,
sulrich@codeaurora.org,
"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
"Emily Deng" <Emily.Deng@amd.com>,
"David Airlie" <airlied@linux.ie>,
linux-arm-msm@vger.kernel.org, timur@codeaurora.org,
"open list" <linux-kernel@vger.kernel.org>,
amd-gfx@lists.freedesktop.org,
"David Panariti" <David.Panariti@amd.com>,
"Jim Qu" <Jim.Qu@amd.com>, "Roger He" <Hongbo.He@amd.com>,
"Monk Liu" <Monk.Liu@amd.com>, "Feifei Xu" <Feifei.Xu@amd.com>,
"Alex Deucher" <alexander.deucher@amd.com>,
"Felix Kuehling" <Felix.Kuehling@amd.com>,
"Christian König" <christian.koenig@amd.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V2] drm/amdgpu: limit DMA size to PAGE_SIZE for scatter-gather buffers
Date: Wed, 11 Apr 2018 11:17:04 +0200 [thread overview]
Message-ID: <6f99b01f-2f3c-7263-9df8-f8a73f4a9372@amd.com> (raw)
In-Reply-To: <20180411062602.GA29109@hr-amur2>
Am 11.04.2018 um 08:26 schrieb Huang Rui:
> On Tue, Apr 10, 2018 at 04:59:55PM -0400, Sinan Kaya wrote:
>> Code is expecing to observe the same number of buffers returned from
>> dma_map_sg() function compared to sg_alloc_table_from_pages(). This
>> doesn't hold true universally especially for systems with IOMMU.
>>
>> IOMMU driver tries to combine buffers into a single DMA address as much
>> as it can. The right thing is to tell the DMA layer how much combining
>> IOMMU can do.
>>
>> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> Sinan, I guess Christian's suggestion is to add amdgpu_device_init function
> like here:
Yes, exactly. Looks like Sinan just tried to place the call next to
pci_set_dma_mask()/pci_set_consistent_dma_mask().
Not necessary a bad idea, but in this case not optimal.
Sinan please refine your patch as Rui suggested and resend.
Thanks,
Christian.
>
> 8<-------
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 0e798b3..9b96771 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -2339,6 +2339,8 @@ int amdgpu_device_init(struct amdgpu_device *adev,
> /* init the mode config */
> drm_mode_config_init(adev->ddev);
>
> + dma_set_max_seg_size(adev->dev, PAGE_SIZE);
> +
> r = amdgpu_device_ip_init(adev);
> if (r) {
> /* failed in exclusive mode due to timeout */
> 8<-------
>
> After that, we don't do it in each generation.
>
> Thanks,
> Ray
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2018-04-11 9:17 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-10 20:59 [PATCH V2] drm/amdgpu: limit DMA size to PAGE_SIZE for scatter-gather buffers Sinan Kaya
2018-04-11 6:26 ` Huang Rui
2018-04-11 9:17 ` Christian König [this message]
2018-04-11 12:03 ` Robin Murphy
2018-04-11 14:33 ` Sinan Kaya
2018-04-11 15:32 ` Robin Murphy
2018-04-12 6:26 ` Christoph Hellwig
2018-04-12 9:42 ` Christian König
2018-04-12 13:51 ` Robin Murphy
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