On Tue, Jul 04, 2017 at 05:18:28PM +0200, Daniel Vetter wrote:
> Those are now all protected using fb_helper->lock.
>
> v2: We still need to hold mode_config.mutex right around calling
> connector->fill_modes.
>
> v3: I forgot to hold mode_config.mutex while looking at
> connector->status and the mode list. Also, we need to patch up the
> i915 ->initial_config callback to grab the locks it needs to inspect
> the modeset state recovered from the fw.
>
> Cc: John Stultz <john.stultz@xxxxxxxxxx>
> Cc: Thierry Reding <treding@xxxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> ---
> drivers/gpu/drm/drm_fb_helper.c | 33 ++++++++-------------------------
> drivers/gpu/drm/drm_vblank.c | 2 +-
> drivers/gpu/drm/i915/intel_fbdev.c | 16 ++++++++++++----
> 3 files changed, 21 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 400bbb07eff2..59e2916471b2 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
<snip>
> @@ -2296,12 +2284,8 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper,
> int i;
>
> DRM_DEBUG_KMS("\n");
> - if (drm_fb_helper_probe_connector_modes(fb_helper, width, height) == 0)
> - DRM_DEBUG_KMS("No connectors reported connected with modes\n");
> -
> /* prevent concurrent modification of connector_count by hotplug */
> lockdep_assert_held(&fb_helper->lock);
> - lockdep_assert_held(&fb_helper->dev->mode_config.mutex);
>
> crtcs = kcalloc(fb_helper->connector_count,
> sizeof(struct drm_fb_helper_crtc *), GFP_KERNEL);
> @@ -2316,7 +2300,10 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper,
> goto out;
> }
>
> + mutex_lock(&fb_helper->dev->mode_config.mutex);
> drm_enable_connectors(fb_helper, enabled);
> + if (drm_fb_helper_probe_connector_modes(fb_helper, width, height) == 0)
This changes the order of these two functions calls. Looks to me like
drm_fb_helper_probe_connector_modes() updates connector->status, and
drm_enable_connectors() depends on it. So either these shouldn't get
reordered or there's some not immediately obvious reason why that's OK.
> + DRM_DEBUG_KMS("No connectors reported connected with modes\n");
>
> if (!(fb_helper->funcs->initial_config &&
> fb_helper->funcs->initial_config(fb_helper, crtcs, modes,
--
Ville Syrjälä
Intel OTC
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