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drm/exynos: dsi: Fix bridge chain handling 

Commit 05193dc381 ("drm/bridge: Make the bridge chain a double-linked
list") patched the bridge chain logic to use a double-linked list instead
of a single-linked list. This change induced changes to the Exynos driver
which was manually resetting the encoder->bridge element to NULL to
control the enable/disable sequence of the bridge chain. During this
conversion, 2 bugs were introduced:

1/ list_splice() was used to move chain elements to our own internal
   chain, but list_splice() does not reset the source list to an empty
   state, leading to unexpected bridge hook calls when
   drm_bridge_chain_xxx() helpers were called by the core. Replacing
   the list_splice() call by list_splice_init() fixes this problem.

2/ drm_bridge_chain_xxx() helpers operate on the
   bridge->encoder->bridge_chain list, which is now empty. When the
   helper uses list_for_each_entry_reverse() we end up with no operation
   done which is not what we want. But that's even worse when the helper
   uses list_for_each_entry_from(), because in that case we end up in
   an infinite loop searching for the list head element which is no
   longer encoder->bridge_chain but exynos_dsi->bridge_chain. To address
   that problem we stop using the bridge chain helpers and call the
   hooks directly.

Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Fixes: 05193dc381 ("drm/bridge: Make the bridge chain a double-linked list")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191227144124.210294-3-boris.brezillon@collabora.com
This commit is contained in:
Boris Brezillon 2019-12-27 15:41:24 +01:00
parent 033bfe7538
commit f66ff55a9b
1 changed files with 24 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
drivers/gpu/drm/exynos/exynos_drm_dsi.c
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@ -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, &dsi->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, &dsi->bridge_chain, chain_node) {
if (iter->funcs->enable)
iter->funcs->enable(iter);
}
}
dsi->state |= DSIM_STATE_VIDOUT_AVAILABLE;
@ -1420,6 +1428,7 @@ err_put_sync:
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, &dsi->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, &dsi->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);