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From: Zack Rusin <zack.rusin@broadcom.com>
To: Ian Forbes <ian.forbes@broadcom.com>
Cc: dri-devel@lists.freedesktop.org,
	bcm-kernel-feedback-list@broadcom.com,
	 martin.krastev@broadcom.com, maaz.mombasawala@broadcom.com
Subject: Re: [PATCH] drm/vmwgfx: Don't memcmp equivalent pointers
Date: Thu, 28 Mar 2024 21:22:01 -0400	[thread overview]
Message-ID: <CABQX2QOm3EcpMKT=YB=1wd86WdDY_Uy2jEGD=n3Qz_huGGkVuQ@mail.gmail.com> (raw)
In-Reply-To: <20240328190716.27367-1-ian.forbes@broadcom.com>

On Thu, Mar 28, 2024 at 3:31 PM Ian Forbes <ian.forbes@broadcom.com> wrote:
>
> These pointers are frequently the same and memcmp does not compare the pointers
> before comparing their contents so this was wasting cycles comparing 16 KiB of
> memory which will always be equal.
>
> Fixes: bb6780aa5a1d9 ("drm/vmwgfx: Diff cursors when using cmds")
> Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index cd4925346ed4..fbcce84e2f4c 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -216,7 +216,7 @@ static bool vmw_du_cursor_plane_has_changed(struct vmw_plane_state *old_vps,
>         new_image = vmw_du_cursor_plane_acquire_image(new_vps);
>
>         changed = false;
> -       if (old_image && new_image)
> +       if (old_image && new_image && (old_image != new_image))
>                 changed = memcmp(old_image, new_image, size) != 0;
>
>         return changed;
> --
> 2.34.1
>

The patch looks good but please use "dim checkpatch" and fix the
issues it found. For the "Fixes:" line you also want to use "dim
fixes".

z

  reply	other threads:[~2024-03-29  1:22 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-28 19:07 [PATCH] drm/vmwgfx: Don't memcmp equivalent pointers Ian Forbes
2024-03-29  1:22 ` Zack Rusin [this message]
2024-04-05 15:02 ` [PATCH v2] " Ian Forbes

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