On 18/02/2025 09:52, AngeloGioacchino Del Regno wrote:
Il 17/02/25 16:03, Alexandre Mergnat ha scritto:
Hi CK.
On 17/02/2025 08:56, CK Hu (胡俊光) wrote:
On Fri, 2025-01-10 at 14:31 +0100, Alexandre Mergnat wrote:
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Currently, mtk_dsi_lane_ready (which setup the DSI lane) is triggered
before mtk_dsi_poweron. lanes_ready flag toggle to true during
mtk_dsi_lane_ready function, and the DSI module is set up during
mtk_dsi_poweron.
Later, during panel driver init, mtk_dsi_lane_ready is triggered but does
nothing because lanes are considered ready. Unfortunately, when the panel
driver try to communicate, the DSI returns a timeout.
The solution found here is to put lanes_ready flag to false after the DSI
module setup into mtk_dsi_poweron to init the DSI lanes after the power /
setup of the DSI module.
I'm not clear about what happen.
I think this DSI flow has worked for a long time.
So only some panel has problem?
I don't know if it's related to a specific panel or not.
And another question.
Do you mean mtk_dsi_lane_ready() do some setting to hardware, but lane is not actually ready?
The workflow should be:
... | dsi->lanes_ready = false | Power-on | setup dsi lanes | dsi->lanes_ready = true (to avoid
re-do dsi lanes setup) | ...
I observe (print function name called + dsi->lanes_ready value):
Alex, the first poweron is called by mtk_dsi_ddp_start() - and the start callback
is internal to the mediatek-drm driver.
That callback is called by mtk_crtc during setup and during bridge enable(), and
there we go with suboptimal code design backfiring - instead of using what the
DRM APIs provide, this driver uses something custom *and* the DRM APIs, giving
this issue.
Part of what mtk_crtc does is duplicated with what the DRM APIs want to do, so
there you go, that's your problem here :-)
Should I go on with describing the next step(s), or is that obvious for everyone?
:-)
Cheers,
Ok thanks Angelo.
Can you let me know if you agree with this change please ? This should be better:
@@ -843,25 +843,6 @@ static void mtk_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
mtk_output_dsi_enable(dsi);
}
-static void mtk_dsi_bridge_atomic_pre_enable(struct drm_bridge *bridge,
- struct drm_bridge_state *old_bridge_state)
-{
- struct mtk_dsi *dsi = bridge_to_dsi(bridge);
- int ret;
-
- ret = mtk_dsi_poweron(dsi);
- if (ret < 0)
- DRM_ERROR("failed to power on dsi\n");
-}
-
-static void mtk_dsi_bridge_atomic_post_disable(struct drm_bridge *bridge,
- struct drm_bridge_state *old_bridge_state)
-{
- struct mtk_dsi *dsi = bridge_to_dsi(bridge);
-
- mtk_dsi_poweroff(dsi);
-}
-
static enum drm_mode_status
mtk_dsi_bridge_mode_valid(struct drm_bridge *bridge,
const struct drm_display_info *info,
@@ -886,8 +867,6 @@ static const struct drm_bridge_funcs mtk_dsi_bridge_funcs = {
.atomic_disable = mtk_dsi_bridge_atomic_disable,
.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
.atomic_enable = mtk_dsi_bridge_atomic_enable,
- .atomic_pre_enable = mtk_dsi_bridge_atomic_pre_enable,
- .atomic_post_disable = mtk_dsi_bridge_atomic_post_disable,
.atomic_reset = drm_atomic_helper_bridge_reset,
.mode_valid = mtk_dsi_bridge_mode_valid,
.mode_set = mtk_dsi_bridge_mode_set,
--
Regards,
Alexandre
