[PATCH 7/8] drm/amdgpu: reserve vram for memory training

Mon Oct 14 08:26:07 UTC 2019

Am 12.10.19 um 01:23 schrieb Tuikov, Luben:
> On 2019-10-10 11:50 p.m., Tianci Yin wrote:
>> From: "Tianci.Yin" <tianci.yin at amd.com>
>>
>> memory training using specific fixed vram segment, reserve these
>> segments before anyone may allocate it.
>>
>> Change-Id: I1436755813a565608a2857a683f535377620a637
>> Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
>> Signed-off-by: Tianci.Yin <tianci.yin at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 96 +++++++++++++++++++++++++
>>   1 file changed, 96 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index 9da6350a4ba2..42d0fcb98382 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -1667,6 +1667,93 @@ static int amdgpu_ttm_fw_reserve_vram_init(struct amdgpu_device *adev)
>>   					  &adev->fw_vram_usage.va);
>>   }
>>   
>> +/*
>> + * Memoy training reservation functions
>> + */
>> +
>> +/**
>> + * amdgpu_ttm_training_reserve_vram_fini - free memory training reserved vram
>> + *
>> + * @adev: amdgpu_device pointer
>> + *
>> + * free memory training reserved vram if it has been reserved.
>> + */
>> +static int amdgpu_ttm_training_reserve_vram_fini(struct amdgpu_device *adev)
>> +{
>> +	struct psp_memory_training_context *ctx = &adev->psp.mem_train_ctx;
>> +
>> +	ctx->init = PSP_MEM_TRAIN_NOT_SUPPORT;
>> +	if (ctx->c2p_bo) {
>> +		amdgpu_bo_free_kernel(&ctx->c2p_bo, NULL, NULL);
>> +		ctx->c2p_bo = NULL;
>> +	}
> Generally it is a good idea to paragraph your code.
> So an empty line between if-statements is a good idea.
> However, there is no need in:
>
> ret = f(x);
> if (ret) {
> 	<body of code>
> }
>
> if (blah) {
> 	<body of code>
> }
>
> The above are two (2) well-formed paragraphs.

Additional to that amdgpu_bo_free_kernel() just like kfree() is NULL 
safe for the reason that you shouldn't need "if"s like that one.

E.g. just write:

amdgpu_bo_free_kernel(&ctx->c2p_bo...);

and you are done.

Regards,
Christian.

>
>> +	if (ctx->p2c_bo) {
>> +		amdgpu_bo_free_kernel(&ctx->p2c_bo, NULL, NULL);
>> +		ctx->p2c_bo = NULL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * amdgpu_ttm_training_reserve_vram_init - create bo vram reservation from memory training
>> + *
>> + * @adev: amdgpu_device pointer
>> + *
>> + * create bo vram reservation from memory training.
>> + */
>> +static int amdgpu_ttm_training_reserve_vram_init(struct amdgpu_device *adev)
>> +{
>> +	int ret;
>> +	struct psp_memory_training_context *ctx = &adev->psp.mem_train_ctx;
>> +
>> +	memset(ctx, 0, sizeof(*ctx));
>> +	if (!adev->fw_vram_usage.mem_train_support) {
>> +		DRM_DEBUG("memory training does not support!\n");
>> +		return 0;
>> +	}
>> +
>> +	ctx->c2p_train_data_offset = adev->fw_vram_usage.mem_train_fb_loc;
>> +	ctx->p2c_train_data_offset = (adev->gmc.mc_vram_size - GDDR6_MEM_TRAINING_OFFSET);
>> +	ctx->train_data_size = GDDR6_MEM_TRAINING_DATA_SIZE_IN_BYTES;
>> +
>> +	DRM_DEBUG("train_data_size:%llx,p2c_train_data_offset:%llx,c2p_train_data_offset:%llx.\n",
>> +		  ctx->train_data_size,
>> +		  ctx->p2c_train_data_offset,
>> +		  ctx->c2p_train_data_offset);
>> +
>> +	ret = amdgpu_bo_create_kernel_at(adev,
>> +					 ctx->p2c_train_data_offset,
>> +					 ctx->train_data_size,
>> +					 AMDGPU_GEM_DOMAIN_VRAM,
>> +					 &ctx->p2c_bo,
>> +					 NULL);
>> +	if (ret) {
>> +		DRM_ERROR("alloc p2c_bo failed(%d)!\n", ret);
>> +		ret = -ENOMEM;
>> +		goto err_out;
>> +	}
> NAK!
> Why are you re-writing the error code from "amdgpu_bo_create_kenrel_at()"?
> Pass the error as is.
>
>> +
>> +	ret = amdgpu_bo_create_kernel_at(adev,
>> +					 ctx->c2p_train_data_offset,
>> +					 ctx->train_data_size,
>> +					 AMDGPU_GEM_DOMAIN_VRAM,
>> +					 &ctx->c2p_bo,
>> +					 NULL);
>> +	if (ret) {
>> +		DRM_ERROR("alloc c2p_bo failed(%d)!\n", ret);
>> +		ret = -ENOMEM;
>> +		goto err_out;
>> +	}
> NAK!
> Why are you re-writing the error code from "amdgpu_bo_create_kenrel_at()"?
> Pass the error as is.
>
>> +
>> +	ctx->init = PSP_MEM_TRAIN_RESERVE_SUCCESS;
>> +	return 0;
>> +
>> +err_out:
> Yes... well "err_out" could be any identifier, including
> a variable, as our variables follow snake-notation, all lowercase.
>
> Back at the turn of this century, Linux followed capitalized
> goto labels to distinguish them from anything else around
> in the kernel code:
>
> 	goto Bad_err;
> 	...
>
> 	return 0;
> Bad_err:
> 	return bad_gift;
> }
>
> To distinguish that a capitalized identifier is a goto label,
> "Bad_err" and all lower-case label is just another variable
> or function identifier, "bad_gift".
>
> Regards,
> Luben
>
>> +	amdgpu_ttm_training_reserve_vram_fini(adev);
>> +	return ret;
>> +}
>> +
>>   /**
>>    * amdgpu_ttm_init - Init the memory management (ttm) as well as various
>>    * gtt/vram related fields.
>> @@ -1740,6 +1827,14 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>>   		return r;
>>   	}
>>   
>> +	/*
>> +	 *The reserved vram for memory training must be pinned to the specified
>> +	 *place on the VRAM, so reserve it early.
>> +	 */
>> +	r = amdgpu_ttm_training_reserve_vram_init(adev);
>> +	if (r)
>> +		return r;
>> +
>>   	/* allocate memory as required for VGA
>>   	 * This is used for VGA emulation and pre-OS scanout buffers to
>>   	 * avoid display artifacts while transitioning between pre-OS
>> @@ -1825,6 +1920,7 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
>>   		return;
>>   
>>   	amdgpu_ttm_debugfs_fini(adev);
>> +	amdgpu_ttm_training_reserve_vram_fini(adev);
>>   	amdgpu_ttm_fw_reserve_vram_fini(adev);
>>   	if (adev->mman.aper_base_kaddr)
>>   		iounmap(adev->mman.aper_base_kaddr);
>>