[PATCH 1/3] drm/radeon: Disable dma rings for bo moves on r6xx

[Ilija Hadzic]

Alex,

Can you please share some details about the nature or symptom of the 
"instability". One problem that I have been seeing on my end is that when 
I use the DMA ring intensively (by intensively I mean, calling the copy 
function every frame), combined with some 3D rendering that causes a lot 
of cs_ioctl calls, that I can provoke a corruption of the olist field in 
radeon_sa_bo structure, consequently causing an oops in 
radeon_sa_bo_try_free(). I have also found that I can suppress the problem 
if I add some padding fields at the beginnig of the radeon_sa_bo structure 
(essentially moving the olist field down).

So I speculate that the use of DMA somehow results in corrupting that 
structure, but I have not yet done enough experiments to prove or disprove 
that theory (so I have not spoke up yet). Also my kernel is full of my own 
internal hacks, and I have not yet taken the time to reproduce the problem 
with the "stock" kernel. However, after seeing your patch series, I am 
wondering if the instability you are referring to may be of the same 
or similar nature.

thanks,

Ilija


On Thu, 11 Jul 2013, alexdeucher at gmail.com wrote:

> From: Alex Deucher <alexander.deucher at amd.com>
>
> They still seem to cause instability on some r6xx parts.
> As a follow up, we can switch to using CP DMA for bo
> moves on r6xx as a lighter weight alternative to using
> the 3D engine.
>
> A version of this patch should also go to stable kernels.
>
> Tested-by: J.N. <golden.fleeced at gmail.com>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
> drivers/gpu/drm/radeon/radeon_asic.c |   12 ++++++------
> 1 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/radeon/radeon_asic.c b/drivers/gpu/drm/radeon/radeon_asic.c
> index 0970774..ea5c52b 100644
> --- a/drivers/gpu/drm/radeon/radeon_asic.c
> +++ b/drivers/gpu/drm/radeon/radeon_asic.c
> @@ -1026,8 +1026,8 @@ static struct radeon_asic r600_asic = {
> 		.blit_ring_index = RADEON_RING_TYPE_GFX_INDEX,
> 		.dma = &r600_copy_dma,
> 		.dma_ring_index = R600_RING_TYPE_DMA_INDEX,
> -		.copy = &r600_copy_dma,
> -		.copy_ring_index = R600_RING_TYPE_DMA_INDEX,
> +		.copy = &r600_copy_blit,
> +		.copy_ring_index = RADEON_RING_TYPE_GFX_INDEX,
> 	},
> 	.surface = {
> 		.set_reg = r600_set_surface_reg,
> @@ -1119,8 +1119,8 @@ static struct radeon_asic rv6xx_asic = {
> 		.blit_ring_index = RADEON_RING_TYPE_GFX_INDEX,
> 		.dma = &r600_copy_dma,
> 		.dma_ring_index = R600_RING_TYPE_DMA_INDEX,
> -		.copy = &r600_copy_dma,
> -		.copy_ring_index = R600_RING_TYPE_DMA_INDEX,
> +		.copy = &r600_copy_blit,
> +		.copy_ring_index = RADEON_RING_TYPE_GFX_INDEX,
> 	},
> 	.surface = {
> 		.set_reg = r600_set_surface_reg,
> @@ -1229,8 +1229,8 @@ static struct radeon_asic rs780_asic = {
> 		.blit_ring_index = RADEON_RING_TYPE_GFX_INDEX,
> 		.dma = &r600_copy_dma,
> 		.dma_ring_index = R600_RING_TYPE_DMA_INDEX,
> -		.copy = &r600_copy_dma,
> -		.copy_ring_index = R600_RING_TYPE_DMA_INDEX,
> +		.copy = &r600_copy_blit,
> +		.copy_ring_index = RADEON_RING_TYPE_GFX_INDEX,
> 	},
> 	.surface = {
> 		.set_reg = r600_set_surface_reg,
> -- 
> 1.7.7.5
>
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