On Fri, 27 Dec 2019 13:00:04 +0100 Boris Brezillon boris.brezillon@collabora.com wrote:
On Fri, 27 Dec 2019 12:01:35 +0100 Marek Szyprowski m.szyprowski@samsung.com wrote:
Exynos DSI DRM driver uses private calls to out bridge to force certain order of operations during init/exit sequences. This no longer works after conversion of bridge chain to a double-linked list. To fix the regression call bridge related operations manually instead of the generic drm_bridge_chain_*() operations.
I think it'd be worth explaining what the problem is (infinite loop caused by list_for_each_entry() use when the bridge is no longer part of the chain attached to the encoder).
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com Fixes: 05193dc38197 ("drm/bridge: Make the bridge chain a double-linked list")
We also need to fix that in VC4.
This patch is a result of the following discussion: https://www.spinics.net/lists/dri-devel/msg239256.html
drivers/gpu/drm/exynos/exynos_drm_dsi.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c index 3955f84dc893..f5905c239a86 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c @@ -255,7 +255,6 @@ struct exynos_dsi { struct mipi_dsi_host dsi_host; struct drm_connector connector; struct drm_panel *panel;
- struct list_head bridge_chain; struct drm_bridge *out_bridge; struct device *dev;
@@ -1391,7 +1390,8 @@ static void exynos_dsi_enable(struct drm_encoder *encoder) if (ret < 0) goto err_put_sync; } else {
drm_bridge_chain_pre_enable(dsi->out_bridge);
if (dsi->out_bridge->funcs->pre_enable)dsi->out_bridge->funcs->pre_enable(dsi->out_bridge);Okay, so you're calling ->{pre_enable,enable,disable,post_disable}() on the first bridge element which only works if the chain contains one bridge (see below). Maybe you should keep exynos_dsi.bridge_chain and create custom helpers to iterate over chain elements instead of calling those hooks only on out_bridge.
The following diff should fix the problem while keeping the solution generic enough to support chains containing more than one bridge.
--->8--- diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c index 3955f84dc893..c861b640fc59 100644 --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c @@ -1378,6 +1378,7 @@ static void exynos_dsi_unregister_te_irq(struct exynos_dsi *dsi) static void exynos_dsi_enable(struct drm_encoder *encoder) { struct exynos_dsi *dsi = encoder_to_dsi(encoder); + struct drm_bridge *iter; int ret;
if (dsi->state & DSIM_STATE_ENABLED) @@ -1391,7 +1392,11 @@ static void exynos_dsi_enable(struct drm_encoder *encoder) if (ret < 0) goto err_put_sync; } else { - drm_bridge_chain_pre_enable(dsi->out_bridge); + list_for_each_entry_reverse(iter, &encoder->bridge_chain, + chain_node) { + if (iter->funcs->pre_enable) + iter->funcs->pre_enable(iter); + } }
exynos_dsi_set_display_mode(dsi); @@ -1402,7 +1407,10 @@ static void exynos_dsi_enable(struct drm_encoder *encoder) if (ret < 0) goto err_display_disable; } else { - drm_bridge_chain_enable(dsi->out_bridge); + list_for_each_entry(iter, &encoder->bridge_chain, chain_node) { + if (iter->funcs->enable) + iter->funcs->enable(iter); + } }
dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE; @@ -1420,6 +1428,7 @@ static void exynos_dsi_enable(struct drm_encoder *encoder) static void exynos_dsi_disable(struct drm_encoder *encoder) { struct exynos_dsi *dsi = encoder_to_dsi(encoder); + struct drm_bridge *iter;
if (!(dsi->state & DSIM_STATE_ENABLED)) return; @@ -1427,10 +1436,20 @@ static void exynos_dsi_disable(struct drm_encoder *encoder) dsi->state &= ~DSIM_STATE_VIDOUT_AVAILABLE;
drm_panel_disable(dsi->panel); - drm_bridge_chain_disable(dsi->out_bridge); + + list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) { + if (iter->funcs->disable) + iter->funcs->disable(iter); + } + exynos_dsi_set_display_enable(dsi, false); drm_panel_unprepare(dsi->panel); - drm_bridge_chain_post_disable(dsi->out_bridge); + + list_for_each_entry(iter, &encoder->bridge_chain, chain_node) { + if (iter->funcs->post_disable) + iter->funcs->post_disable(iter); + } + dsi->state &= ~DSIM_STATE_ENABLED; pm_runtime_put_sync(dsi->dev); } @@ -1523,7 +1542,7 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host, if (out_bridge) { drm_bridge_attach(encoder, out_bridge, NULL); dsi->out_bridge = out_bridge; - list_splice(&encoder->bridge_chain, &dsi->bridge_chain); + list_splice_init(&encoder->bridge_chain, &dsi->bridge_chain); } else { int ret = exynos_dsi_create_connector(encoder);