Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Thomas Zimmermann <tzimmermann@suse.de>
To:     Gerd Hoffmann <kraxel@redhat.com>, dri-devel@lists.freedesktop.org
Cc:     David Airlie <airlied@linux.ie>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <spice-devel@lists.freedesktop.org>,
        Dave Airlie <airlied@redhat.com>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:DRM DRIVER FOR QXL VIRTUAL GPU" 
        <virtualization@lists.linux-foundation.org>
References: <20210216113716.716996-1-kraxel@redhat.com>
 <20210216113716.716996-10-kraxel@redhat.com>
 <5baf096f-b1ee-46ba-5ee9-1c829b96e088@suse.de>
Subject: Re: [PATCH 09/10] drm/qxl: map/unmap framebuffers in
 prepare_fb+cleanup_fb callbacks.
Message-ID: <ab21d782-2627-7a68-8fab-0acfba416c86@suse.de>
Date:   Tue, 16 Feb 2021 14:46:21 +0100
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From: Thomas Zimmermann <tzimmermann@suse.de>
To: Gerd Hoffmann <kraxel@redhat.com>, dri-devel@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>,
 "open list:DRM DRIVER FOR QXL VIRTUAL GPU"
 <spice-devel@lists.freedesktop.org>, Dave Airlie <airlied@redhat.com>,
 open list <linux-kernel@vger.kernel.org>,
 "open list:DRM DRIVER FOR QXL VIRTUAL GPU"
 <virtualization@lists.linux-foundation.org>
Message-ID: <ab21d782-2627-7a68-8fab-0acfba416c86@suse.de>
Subject: Re: [PATCH 09/10] drm/qxl: map/unmap framebuffers in
 prepare_fb+cleanup_fb callbacks.
References: <20210216113716.716996-1-kraxel@redhat.com>
 <20210216113716.716996-10-kraxel@redhat.com>
 <5baf096f-b1ee-46ba-5ee9-1c829b96e088@suse.de>
In-Reply-To: <5baf096f-b1ee-46ba-5ee9-1c829b96e088@suse.de>

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Am 16.02.21 um 14:27 schrieb Thomas Zimmermann:
> Hi
>=20
> this is a shadow-buffered plane. Did you consider using the new helpers=
=20
> for shadow-buffered planes? They will map the user BO for you and=20
> provide the mapping in the plane state.
>=20
>  From there, you should implement your own plane state on top of struct=
=20
> drm_shadow_plane_state, and also move all the other allocations and=20
> vmaps into prepare_fb and cleanup_fb. Most of this is not actually=20
> allowed in commit tails. All we'd have to do is to export the reset,=20
> duplicate and destroy code; similar to what=20
> __drm_atomic_helper_plane_reset() does.

AFAICT the cursor_bo is used to implement double buffering for the=20
cursor image.

Ideally, you can do what ast does: pre-allocate/vmap 2 BOs at the end of =

the vram. Then pageflip between them in atomic_update(). Resolves all=20
the allocation and mapping headaches.

Best regards
Thomas

>=20
> Best regards
> Thomas
>=20
>=20
> Am 16.02.21 um 12:37 schrieb Gerd Hoffmann:
>> We don't have to map in atomic_update callback then,
>> making locking a bit less complicated.
>>
>> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
>> ---
>> =C2=A0 drivers/gpu/drm/qxl/qxl_display.c | 14 +++++---------
>> =C2=A0 1 file changed, 5 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/qxl/qxl_display.c=20
>> b/drivers/gpu/drm/qxl/qxl_display.c
>> index 7500560db8e4..39b8c5116d34 100644
>> --- a/drivers/gpu/drm/qxl/qxl_display.c
>> +++ b/drivers/gpu/drm/qxl/qxl_display.c
>> @@ -584,7 +584,6 @@ static void qxl_cursor_atomic_update(struct=20
>> drm_plane *plane,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct drm_gem_object *obj;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct qxl_bo *cursor_bo =3D NULL, *use=
r_bo =3D NULL, *old_cursor_bo=20
>> =3D NULL;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 int ret;
>> -=C2=A0=C2=A0=C2=A0 struct dma_buf_map user_map;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct dma_buf_map cursor_map;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 void *user_ptr;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 int size =3D 64*64*4;
>> @@ -599,11 +598,8 @@ static void qxl_cursor_atomic_update(struct=20
>> drm_plane *plane,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 obj =3D fb->obj=
[0];
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 user_bo =3D gem=
_to_qxl_bo(obj);
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* pinning is done in the =
prepare/cleanup framevbuffer */
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ret =3D qxl_bo_kmap_locked=
(user_bo, &user_map);
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (ret)
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 go=
to out_free_release;
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 user_ptr =3D user_map.vadd=
r; /* TODO: Use mapping abstraction=20
>> properly */
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 /* mapping is done in the =
prepare/cleanup framevbuffer */
>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 user_ptr =3D user_bo->map.=
vaddr; /* TODO: Use mapping=20
>> abstraction properly */
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 ret =3D qxl_all=
oc_bo_reserved(qdev, release,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 sizeof(struct qxl_cursor) + size,
>> @@ -639,7 +635,6 @@ static void qxl_cursor_atomic_update(struct=20
>> drm_plane *plane,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 cursor->chunk.d=
ata_size =3D size;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 memcpy(cursor->=
chunk.data, user_ptr, size);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 qxl_bo_kunmap_l=
ocked(cursor_bo);
>> -=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 qxl_bo_kunmap_locked(user_=
bo);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 cmd =3D (struct=
 qxl_cursor_cmd *) qxl_release_map(qdev, release);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 cmd->u.set.visi=
ble =3D 1;
>> @@ -778,6 +773,7 @@ static int qxl_plane_prepare_fb(struct drm_plane=20
>> *plane,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct drm_gem_object *obj;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct qxl_bo *user_bo;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 struct qxl_surface surf;
>> +=C2=A0=C2=A0=C2=A0 struct dma_buf_map unused;
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (!new_state->fb)
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 return 0;
>> @@ -815,7 +811,7 @@ static int qxl_plane_prepare_fb(struct drm_plane=20
>> *plane,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }
>> -=C2=A0=C2=A0=C2=A0 return qxl_bo_pin(user_bo);
>> +=C2=A0=C2=A0=C2=A0 return qxl_bo_kmap(user_bo, &unused);
>> =C2=A0 }
>> =C2=A0 static void qxl_plane_cleanup_fb(struct drm_plane *plane,
>> @@ -834,7 +830,7 @@ static void qxl_plane_cleanup_fb(struct drm_plane =

>> *plane,
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 obj =3D old_state->fb->obj[0];
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 user_bo =3D gem_to_qxl_bo(obj);
>> -=C2=A0=C2=A0=C2=A0 qxl_bo_unpin(user_bo);
>> +=C2=A0=C2=A0=C2=A0 qxl_bo_kunmap(user_bo);
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 if (old_state->fb !=3D plane->state->fb=
 && user_bo->shadow) {
>> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 qxl_bo_unpin(us=
er_bo->shadow);
>>
>=20
>=20
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>=20

--=20
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany
(HRB 36809, AG N=C3=BCrnberg)
Gesch=C3=A4ftsf=C3=BChrer: Felix Imend=C3=B6rffer


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