| Message ID | 20180903165439.24845-14-daniel.vetter@ffwll.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/14] drm: Add drm/kernel.h header file | expand |
On 09/03/2018 06:54 PM, Daniel Vetter wrote: > 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. > Thanks for the patch, Daniel Your comments seem valid. We'll try to fix this internally before the next merge window rather than to add the FIXMEs /Thomas
On Tue, Sep 4, 2018 at 3:45 PM, Thomas Hellstrom <thellstrom@vmware.com> wrote: > On 09/03/2018 06:54 PM, Daniel Vetter wrote: >> >> 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. >> > Thanks for the patch, Daniel > > Your comments seem valid. We'll try to fix this internally before the next > merge window rather than to add the FIXMEs Sounds all good to me. And if you have questions I'm happy to help out (and use that generally as an opportunity to improve the docs). Thanks, Daniel
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;
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@intel.com> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com> Cc: Sinclair Yeh <syeh@vmware.com> Cc: Thomas Hellstrom <thellstrom@vmware.com> --- drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c | 2 ++ drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 1 + 2 files changed, 3 insertions(+)