linux-kernel - Re: [PATCH] Optimized division operation to shift operation

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Date:   Tue, 14 Apr 2020 14:15:03 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     Bernard Zhao <bernard@...o.com>
Cc:     Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Felix Kuehling <Felix.Kuehling@....com>,
        Xiaojie Yuan <xiaojie.yuan@....com>,
        Oak Zeng <Oak.Zeng@....com>, Sam Ravnborg <sam@...nborg.org>,
        Alex Sierra <alex.sierra@....com>,
        Huang Rui <ray.huang@....com>,
        Kent Russell <kent.russell@....com>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel@...o.com
Subject: Re: [PATCH] Optimized division operation to shift operation

On Tue, Apr 14, 2020 at 9:05 AM Bernard Zhao <bernard@...o.com> wrote:
>
> On some processors, the / operate will call the compiler`s div lib,
> which is low efficient, We can replace the / operation with shift,
> so that we can replace the call of the division library with one
> shift assembly instruction.
>
> Signed-off-by: Bernard Zhao <bernard@...o.com>

Applied.  thanks.

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c | 4 ++--
>  drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c | 4 ++--
>  drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c | 4 ++--
>  3 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
> index b205039..66cd078 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
> @@ -175,10 +175,10 @@ static int gmc_v6_0_mc_load_microcode(struct amdgpu_device *adev)
>         amdgpu_ucode_print_mc_hdr(&hdr->header);
>
>         adev->gmc.fw_version = le32_to_cpu(hdr->header.ucode_version);
> -       regs_size = le32_to_cpu(hdr->io_debug_size_bytes) / (4 * 2);
> +       regs_size = le32_to_cpu(hdr->io_debug_size_bytes) >> 3;
>         new_io_mc_regs = (const __le32 *)
>                 (adev->gmc.fw->data + le32_to_cpu(hdr->io_debug_array_offset_bytes));
> -       ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) / 4;
> +       ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) >> 2;
>         new_fw_data = (const __le32 *)
>                 (adev->gmc.fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes));
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
> index 9da9596..ca26d63 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v7_0.c
> @@ -193,10 +193,10 @@ static int gmc_v7_0_mc_load_microcode(struct amdgpu_device *adev)
>         amdgpu_ucode_print_mc_hdr(&hdr->header);
>
>         adev->gmc.fw_version = le32_to_cpu(hdr->header.ucode_version);
> -       regs_size = le32_to_cpu(hdr->io_debug_size_bytes) / (4 * 2);
> +       regs_size = le32_to_cpu(hdr->io_debug_size_bytes) >> 3;
>         io_mc_regs = (const __le32 *)
>                 (adev->gmc.fw->data + le32_to_cpu(hdr->io_debug_array_offset_bytes));
> -       ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) / 4;
> +       ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) >> 2;
>         fw_data = (const __le32 *)
>                 (adev->gmc.fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes));
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
> index 27d83204..295039c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v8_0.c
> @@ -318,10 +318,10 @@ static int gmc_v8_0_tonga_mc_load_microcode(struct amdgpu_device *adev)
>         amdgpu_ucode_print_mc_hdr(&hdr->header);
>
>         adev->gmc.fw_version = le32_to_cpu(hdr->header.ucode_version);
> -       regs_size = le32_to_cpu(hdr->io_debug_size_bytes) / (4 * 2);
> +       regs_size = le32_to_cpu(hdr->io_debug_size_bytes) >> 3;
>         io_mc_regs = (const __le32 *)
>                 (adev->gmc.fw->data + le32_to_cpu(hdr->io_debug_array_offset_bytes));
> -       ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) / 4;
> +       ucode_size = le32_to_cpu(hdr->header.ucode_size_bytes) >> 2;
>         fw_data = (const __le32 *)
>                 (adev->gmc.fw->data + le32_to_cpu(hdr->header.ucode_array_offset_bytes));
>
> --
> 2.7.4
>
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx

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