[Intel-gfx] [PATCH 14/14] drm/vmwgfx: Add FIXME comments for customer page_flip handlers

[Daniel Vetter]

The idea behind allowing drivers to override legacy ioctls (instead of
using the generic implementations unconditionally) is to handle bugs
in old driver-specific userspace. Like e.g. vmw_kms_set_config does,
to work around some vmwgfx userspace not clearing its ioctl structs
properly.

But you can't use it to augment semantics and put in additional
checks, since from a correctly working userspace's pov there should
not be any difference in behaviour between the legacy and the atomic
paths.

vmwgfx seems to be doing some strange things in its page_flip
handlers. Since I'm not an expert of this codebase just wrap some
FIXME comments around the potentially problematic code.

Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
Cc: VMware Graphics <linux-graphics-maintainer at vmware.com>
Cc: Sinclair Yeh <syeh at vmware.com>
Cc: Thomas Hellstrom <thellstrom at vmware.com>
---
 drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c | 2 ++
 drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 1 +
 2 files changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c b/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c
index 4c68ad6f3605..8e692334c3b9 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c
@@ -326,6 +326,7 @@ static int vmw_sou_crtc_page_flip(struct drm_crtc *crtc,
 	struct vmw_private *dev_priv = vmw_priv(crtc->dev);
 	int ret;
 
+	/* FIMXE: This check needs to be moved into ->atomic_check code. */
 	if (!vmw_kms_crtc_flippable(dev_priv, crtc))
 		return -EINVAL;
 
@@ -335,6 +336,7 @@ static int vmw_sou_crtc_page_flip(struct drm_crtc *crtc,
 		return ret;
 	}
 
+	/* FIMXE: This code needs to be moved into ->atomic_commit callbacks. */
 	if (vmw_crtc_to_du(crtc)->is_implicit)
 		vmw_kms_update_implicit_fb(dev_priv, crtc);
 
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
index f5b2fe8a7793..1913e086d015 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c
@@ -501,6 +501,7 @@ static int vmw_stdu_crtc_page_flip(struct drm_crtc *crtc,
 	struct vmw_screen_target_display_unit *stdu = vmw_crtc_to_stdu(crtc);
 	int ret;
 
+	/* FIMXE: This check needs to be moved into ->atomic_check code. */
 	if (!stdu->defined || !vmw_kms_crtc_flippable(dev_priv, crtc))
 		return -EINVAL;
 
-- 
2.18.0