Re: [PATCH 4/4] drm/amdgpu: resize VRAM BAR for CPU access

From: Christian KÃnig
Date: Wed Mar 15 2017 - 05:29:31 EST

Yes, exactly that.

Christian.

Am 15.03.2017 um 09:25 schrieb Zhou, David(ChunMing):
Does that means we don't need invisible vram later?

David

-----Original Message-----
From: dri-devel [mailto:dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Christian K?nig
Sent: Wednesday, March 15, 2017 3:38 PM
To: Ayyappa Ch <ayyappa.ch.linux@xxxxxxxxx>
Cc: linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; amd-gfx@xxxxxxxxxxxxxxxxxxxxx; platform-driver-x86@xxxxxxxxxxxxxxx; helgaas@xxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx
Subject: Re: [PATCH 4/4] drm/amdgpu: resize VRAM BAR for CPU access

Carizzo is an APU and resizing BARs isn't needed nor supported there.
The CPU can access the full stolen VRAM directly on that hardware.

As far as I know ASICs with support for this are Tonga, Fiji and all Polaris variants.

Christian.

Am 15.03.2017 um 08:23 schrieb Ayyappa Ch:
Is it possible on Carrizo asics? Or only supports on newer asics?

On Mon, Mar 13, 2017 at 6:11 PM, Christian KÃnig
<deathsimple@xxxxxxxxxxx> wrote:
From: Christian KÃnig <christian.koenig@xxxxxxx>

Try to resize BAR0 to let CPU access all of VRAM.

Signed-off-by: Christian KÃnig <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu.h | 1 +
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 29 +++++++++++++++++++++++++++++
drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c | 8 +++++---
drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c | 8 +++++---
4 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 3b81ded..905ded9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1719,6 +1719,7 @@ uint64_t amdgpu_ttm_tt_pte_flags(struct amdgpu_device *adev, struct ttm_tt *ttm,
struct ttm_mem_reg *mem);
void amdgpu_vram_location(struct amdgpu_device *adev, struct amdgpu_mc *mc, u64 base);
void amdgpu_gtt_location(struct amdgpu_device *adev, struct
amdgpu_mc *mc);
+void amdgpu_resize_bar0(struct amdgpu_device *adev);
void amdgpu_ttm_set_active_vram_size(struct amdgpu_device *adev, u64 size);
int amdgpu_ttm_init(struct amdgpu_device *adev);
void amdgpu_ttm_fini(struct amdgpu_device *adev); diff --git
a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 118f4e6..92955fe 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -692,6 +692,35 @@ void amdgpu_gtt_location(struct amdgpu_device *adev, struct amdgpu_mc *mc)
mc->gtt_size >> 20, mc->gtt_start, mc->gtt_end);
}

+/**
+ * amdgpu_resize_bar0 - try to resize BAR0
+ *
+ * @adev: amdgpu_device pointer
+ *
+ * Try to resize BAR0 to make all VRAM CPU accessible.
+ */
+void amdgpu_resize_bar0(struct amdgpu_device *adev) {
+ u32 size = max(ilog2(adev->mc.real_vram_size - 1) + 1, 20) - 20;
+ int r;
+
+ r = pci_resize_resource(adev->pdev, 0, size);
+
+ if (r == -ENOTSUPP) {
+ /* The hardware don't support the extension. */
+ return;
+
+ } else if (r == -ENOSPC) {
+ DRM_INFO("Not enoigh PCI address space for a large BAR.");
+ } else if (r) {
+ DRM_ERROR("Problem resizing BAR0 (%d).", r);
+ }
+
+ /* Reinit the doorbell mapping, it is most likely moved as well */
+ amdgpu_doorbell_fini(adev);
+ BUG_ON(amdgpu_doorbell_init(adev));
+}
+
/*
* GPU helpers function.
*/
diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
index dc9b6d6..36a7aa5 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
@@ -367,13 +367,15 @@ static int gmc_v7_0_mc_init(struct amdgpu_device *adev)
break;
}
adev->mc.vram_width = numchan * chansize;
- /* Could aper size report 0 ? */
- adev->mc.aper_base = pci_resource_start(adev->pdev, 0);
- adev->mc.aper_size = pci_resource_len(adev->pdev, 0);
/* size in MB on si */
adev->mc.mc_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL * 1024ULL;
adev->mc.real_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL
* 1024ULL;

+ if (!(adev->flags & AMD_IS_APU))
+ amdgpu_resize_bar0(adev);
+ adev->mc.aper_base = pci_resource_start(adev->pdev, 0);
+ adev->mc.aper_size = pci_resource_len(adev->pdev, 0);
+
#ifdef CONFIG_X86_64
if (adev->flags & AMD_IS_APU) {
adev->mc.aper_base =
((u64)RREG32(mmMC_VM_FB_OFFSET)) << 22; diff --git
a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
index c087b00..7761ad3 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
@@ -459,13 +459,15 @@ static int gmc_v8_0_mc_init(struct amdgpu_device *adev)
break;
}
adev->mc.vram_width = numchan * chansize;
- /* Could aper size report 0 ? */
- adev->mc.aper_base = pci_resource_start(adev->pdev, 0);
- adev->mc.aper_size = pci_resource_len(adev->pdev, 0);
/* size in MB on si */
adev->mc.mc_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL * 1024ULL;
adev->mc.real_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL
* 1024ULL;

+ if (!(adev->flags & AMD_IS_APU))
+ amdgpu_resize_bar0(adev);
+ adev->mc.aper_base = pci_resource_start(adev->pdev, 0);
+ adev->mc.aper_size = pci_resource_len(adev->pdev, 0);
+
#ifdef CONFIG_X86_64
if (adev->flags & AMD_IS_APU) {
adev->mc.aper_base =
((u64)RREG32(mmMC_VM_FB_OFFSET)) << 22;
--
2.7.4

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