[PATCH 1/2] drm/amdgpu: add amdgpu.ttm_dma_allocation parameter

[Chunming Zhou]

On 2018年01月25日 16:34, Michel Dänzer wrote:
> On 2018-01-25 07:50 AM, Chunming Zhou wrote:
>> it will be used to set ttm dma allocation path.
>>
>> Change-Id: I9fa936db751811779cea66598bba0b8cf4cfd869
>> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h     | 1 +
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 4 ++++
>>   2 files changed, 5 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> index 353186f3e58c..443bedb288e6 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> @@ -128,6 +128,7 @@ extern int amdgpu_job_hang_limit;
>>   extern int amdgpu_lbpw;
>>   extern int amdgpu_compute_multipipe;
>>   extern int amdgpu_gpu_recovery;
>> +extern int amdgpu_ttm_dma_allocation;
>>   
>>   #ifdef CONFIG_DRM_AMDGPU_SI
>>   extern int amdgpu_si_support;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> index d1a695864793..556135020c4d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> @@ -131,6 +131,7 @@ int amdgpu_job_hang_limit = 0;
>>   int amdgpu_lbpw = -1;
>>   int amdgpu_compute_multipipe = -1;
>>   int amdgpu_gpu_recovery = -1; /* auto */
>> +int amdgpu_ttm_dma_allocation = 0;
>>   
>>   MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing, in megabytes");
>>   module_param_named(vramlimit, amdgpu_vram_limit, int, 0600);
>> @@ -286,6 +287,9 @@ module_param_named(compute_multipipe, amdgpu_compute_multipipe, int, 0444);
>>   MODULE_PARM_DESC(gpu_recovery, "Enable GPU recovery mechanism, (1 = enable, 0 = disable, -1 = auto");
>>   module_param_named(gpu_recovery, amdgpu_gpu_recovery, int, 0444);
>>   
>> +MODULE_PARM_DESC(ttm_dma_allocation, "Enable TTM dma allocation, (1 = enable, 0 = disable");
>> +module_param_named(amdgpu_ttm_dma_allocation, amdgpu_ttm_dma_allocation, int, 0444);
>> +
>>   #ifdef CONFIG_DRM_AMDGPU_SI
>>   
>>   #if defined(CONFIG_DRM_RADEON) || defined(CONFIG_DRM_RADEON_MODULE)
>>
> NAK from me as well.
>
> This isn't something that the administrator/user needs to decide.
We should select better path, shouldn't we?

> Somebody needs to figure out the exact conditions under which the DMA
> allocation path is needed, and make the code match those.
Yeah, agree, this is the best choice, I tried to find out the max_pfn of 
system memory iomapping, but failed, so thought to this method, disabled 
by default in amdgpu driver only, if some platform or special case needs 
it, they can re-enable it again.

Regards,
David Zhou
>
>
> In general, amdgpu already has way too many module parameters. If we
> keep adding more like this, it'll become completely unmanageable soon.
>
>