linux-kernel - Re: [PATCH] drm/hyperv: Fix double mouse pointers

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Message-ID: <CAHFnvW0iX1FMTcJzQQtjHGosavSJ6-9wkRb7C0Ljv3c+BBUEXQ@mail.gmail.com>
Date:   Tue, 14 Sep 2021 08:59:20 -0700
From:   Deepak Rawat <drawat.floss@...il.com>
To:     Dexuan Cui <decui@...rosoft.com>
Cc:     Haiyang Zhang <haiyangz@...rosoft.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        dri-devel@...ts.freedesktop.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/hyperv: Fix double mouse pointers

Thanks Dexuan, for the patch. A minor comment below.

On Mon, Sep 13, 2021 at 11:27 AM Dexuan Cui <decui@...rosoft.com> wrote:
>
> It looks like Hyper-V supports a hardware cursor feature. It is not used
> by Linux VM, but the Hyper-V host still draws a point as an extra mouse
> pointer, which is unwanted, especially when Xorg is running.
>
> The hyperv_fb driver uses synthvid_send_ptr() to hide the unwanted pointer.
> When the hyperv_drm driver was developed, the function synthvid_send_ptr()
> was not copied from the hyperv_fb driver. Fix the issue by adding the
> function into hyperv_drm.
>
> Fixes: 76c56a5affeb ("drm/hyperv: Add DRM driver for hyperv synthetic video device")
> Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> Cc: Deepak Rawat <drawat.floss@...il.com>
> Cc: Haiyang Zhang <haiyangz@...rosoft.com>
> ---
>  drivers/gpu/drm/hyperv/hyperv_drm.h         |  1 +
>  drivers/gpu/drm/hyperv/hyperv_drm_modeset.c |  1 +
>  drivers/gpu/drm/hyperv/hyperv_drm_proto.c   | 39 ++++++++++++++++++++-
>  3 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm.h b/drivers/gpu/drm/hyperv/hyperv_drm.h
> index 886add4f9cd0..27bfd27c05be 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm.h
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm.h
> @@ -46,6 +46,7 @@ int hyperv_mode_config_init(struct hyperv_drm_device *hv);
>  int hyperv_update_vram_location(struct hv_device *hdev, phys_addr_t vram_pp);
>  int hyperv_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
>                             u32 w, u32 h, u32 pitch);
> +int hyperv_send_ptr(struct hv_device *hdev);
>  int hyperv_update_dirt(struct hv_device *hdev, struct drm_rect *rect);
>  int hyperv_connect_vsp(struct hv_device *hdev);
>
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> index 3aaee4730ec6..e21c82cf3326 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_modeset.c
> @@ -101,6 +101,7 @@ static void hyperv_pipe_enable(struct drm_simple_display_pipe *pipe,
>         struct hyperv_drm_device *hv = to_hv(pipe->crtc.dev);
>         struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
>
> +       hyperv_send_ptr(hv->hdev);
>         hyperv_update_situation(hv->hdev, 1,  hv->screen_depth,
>                                 crtc_state->mode.hdisplay,
>                                 crtc_state->mode.vdisplay,
> diff --git a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
> index 6d4bdccfbd1a..1ea7a0432320 100644
> --- a/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
> +++ b/drivers/gpu/drm/hyperv/hyperv_drm_proto.c
> @@ -299,6 +299,40 @@ int hyperv_update_situation(struct hv_device *hdev, u8 active, u32 bpp,
>         return 0;
>  }
>
> +/* Send mouse pointer info to host */
> +int hyperv_send_ptr(struct hv_device *hdev)
> +{
> +       struct synthvid_msg msg;
> +
> +       memset(&msg, 0, sizeof(struct synthvid_msg));
> +       msg.vid_hdr.type = SYNTHVID_POINTER_POSITION;
> +       msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +               sizeof(struct synthvid_pointer_position);
> +       msg.ptr_pos.is_visible = 1;

"is_visible" should be 0 since you want to hide the pointer. Maybe
better, accept these from the caller.

> +       msg.ptr_pos.video_output = 0;
> +       msg.ptr_pos.image_x = 0;
> +       msg.ptr_pos.image_y = 0;
> +       hyperv_sendpacket(hdev, &msg);
> +
> +       memset(&msg, 0, sizeof(struct synthvid_msg));
> +       msg.vid_hdr.type = SYNTHVID_POINTER_SHAPE;
> +       msg.vid_hdr.size = sizeof(struct synthvid_msg_hdr) +
> +               sizeof(struct synthvid_pointer_shape);
> +       msg.ptr_shape.part_idx = SYNTHVID_CURSOR_COMPLETE;
> +       msg.ptr_shape.is_argb = 1;
> +       msg.ptr_shape.width = 1;
> +       msg.ptr_shape.height = 1;
> +       msg.ptr_shape.hot_x = 0;
> +       msg.ptr_shape.hot_y = 0;
> +       msg.ptr_shape.data[0] = 0;
> +       msg.ptr_shape.data[1] = 1;
> +       msg.ptr_shape.data[2] = 1;
> +       msg.ptr_shape.data[3] = 1;
> +       hyperv_sendpacket(hdev, &msg);
> +

Is it necessary to send SYNTHVID_POINTER_SHAPE here? Perhaps we should
separate SYNTHVID_POINTER_POSITION and SYNTHVID_POINTER_SHAPE into
different functions.

> +       return 0;
> +}
> +
>  int hyperv_update_dirt(struct hv_device *hdev, struct drm_rect *rect)
>  {
>         struct hyperv_drm_device *hv = hv_get_drvdata(hdev);
> @@ -392,8 +426,11 @@ static void hyperv_receive_sub(struct hv_device *hdev)
>                 return;
>         }
>
> -       if (msg->vid_hdr.type == SYNTHVID_FEATURE_CHANGE)
> +       if (msg->vid_hdr.type == SYNTHVID_FEATURE_CHANGE) {
>                 hv->dirt_needed = msg->feature_chg.is_dirt_needed;
> +               if (hv->dirt_needed)
> +                       hyperv_send_ptr(hv->hdev);
> +       }
>  }
>
>  static void hyperv_receive(void *ctx)
> --
> 2.25.1
>