[PATCH 7/8] drm/amdgpu: reserve vram for memory training
Yin, Tianci (Rico)
Tianci.Yin at amd.com
Wed Oct 9 11:50:41 UTC 2019
Oh, I see, I thought we should eliminate warning, but it's a wrong idea, actually we need it.
Thanks!
Rico
________________________________
From: Christian K?nig <ckoenig.leichtzumerken at gmail.com>
Sent: Wednesday, October 9, 2019 19:40
To: Yin, Tianci (Rico) <Tianci.Yin at amd.com>; Tuikov, Luben <Luben.Tuikov at amd.com>; Alex Deucher <alexdeucher at gmail.com>; amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>
Cc: Deucher, Alexander <Alexander.Deucher at amd.com>
Subject: Re: [PATCH 7/8] drm/amdgpu: reserve vram for memory training
Am 09.10.19 um 13:12 schrieb Yin, Tianci (Rico):
Here is where you definitively set "ret" so DO NOT preinitialize it to 0,
just to avoid "pesky compiler unininitialized variable warnings"--those
are helpful to make the code more secure: a variable should be intentionally
initialized in all paths.
Rico: Still in confusion, pre-initialization can avoid "uninitialized variable", why should we can't pre-initialize?
Because it avoids the uninitialized variable warning :)
See we really want the warning because it means that we have a bug in the code somewhere.
Regards,
Christian.
________________________________
From: Tuikov, Luben <Luben.Tuikov at amd.com><mailto:Luben.Tuikov at amd.com>
Sent: Wednesday, October 9, 2019 11:44
To: Alex Deucher <alexdeucher at gmail.com><mailto:alexdeucher at gmail.com>; amd-gfx at lists.freedesktop.org<mailto:amd-gfx at lists.freedesktop.org> <amd-gfx at lists.freedesktop.org><mailto:amd-gfx at lists.freedesktop.org>
Cc: Deucher, Alexander <Alexander.Deucher at amd.com><mailto:Alexander.Deucher at amd.com>; Yin, Tianci (Rico) <Tianci.Yin at amd.com><mailto:Tianci.Yin at amd.com>
Subject: Re: [PATCH 7/8] drm/amdgpu: reserve vram for memory training
On 2019-10-08 3:29 p.m., Alex Deucher wrote:
> From: "Tianci.Yin" <tianci.yin at amd.com><mailto: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><mailto:alexander.deucher at amd.com>
> Signed-off-by: Tianci.Yin <tianci.yin at amd.com><mailto: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 74a9bd94f10c..0819721af16e 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
> + */
Include an empty line between the two comments, just as you would
a paragraph in written text.
> +/**
> + * 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)
> +{
> + int ret = 0;
> + struct psp_memory_training_context *ctx = &adev->psp.mem_train_ctx;
> +
> + ctx->init = PSP_MEM_TRAIN_NOT_SUPPORT;
> + if(ctx->c2p_bo) {
Space after keywords, according to LKCS:
if (...)
> + amdgpu_bo_free_kernel(&ctx->c2p_bo, NULL, NULL);
> + ctx->c2p_bo = NULL;
> + }
> + if(ctx->p2c_bo) {
Space after keywords, according to LKCS:
if (...)
> + amdgpu_bo_free_kernel(&ctx->p2c_bo, NULL, NULL);
> + ctx->p2c_bo = NULL;
> + }
> +
> + return ret;
> +}
Get rid of "ret" variable altogether as it is not used in this function.
> +
> +/**
> + * 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 = 0;
DO NOT preinitialize 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) {
Space after keywords: "if (".
> + 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,
Here is where you definitively set "ret" so DO NOT preinitialize it to 0,
just to avoid "pesky compiler unininitialized variable warnings"--those
are helpful to make the code more secure: a variable should be intentionally
initialized in all paths.
> + ctx->p2c_train_data_offset,
> + ctx->train_data_size,
> + AMDGPU_GEM_DOMAIN_VRAM,
> + &ctx->p2c_bo,
> + NULL);
> + if(ret) {
Space after keywords "if (".
> + DRM_ERROR("alloc p2c_bo failed(%d)!\n", ret);
> + ret = -ENOMEM;
> + goto err_out;
> + }
> +
> + 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) {
Space after keywords: "if (", according to LKCS.
Regards,
Luben
> + DRM_ERROR("alloc c2p_bo failed(%d)!\n", ret);
> + ret = -ENOMEM;
> + goto err_out;
> + }
> +
> + ctx->init = PSP_MEM_TRAIN_RESERVE_SUCCESS;
> + return 0;
> +
> +err_out:
> + 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);
>
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