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drm/bridge: ti-sn65dsi86: Add HPD for DisplayPort connector type

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By default, HPD was disabled on SN65DSI86 bridge. When the driver was
added (commit "a095f15c00e27"), the HPD_DISABLE bit was set in pre-enable
call which was moved to other function calls subsequently.
Later on, commit "c312b0df3b13" added detect utility for DP mode. But with
HPD_DISABLE bit set, all the HPD events are disabled[0] and the debounced
state always return 1 (always connected state).

Set HPD_DISABLE bit conditionally based on display sink's connector type.
Since the HPD_STATE is reflected correctly only after waiting for debounce
time (~100-400ms) and adding this delay in detect() is not feasible
owing to the performace impact (glitches and frame drop), remove runtime
calls in detect() and add hpd_enable()/disable() bridge hooks with runtime
calls, to detect hpd properly without any delay.

[0]: <https://www.ti.com/lit/gpn/SN65DSI86> (Pg. 32)

Fixes: c312b0df3b ("drm/bridge: ti-sn65dsi86: Implement bridge connector operations for DP")
Cc: Max Krummenacher <max.krummenacher@toradex.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Ernest Van Hoecke <ernest.vanhoecke@toradex.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20250624044835.165708-1-j-choudhary@ti.com
This commit is contained in:
Jayesh Choudhary 2025-06-24 10:18:35 +05:30 committed by Douglas Anderson
parent 1035782415
commit 55e8ff8420
1 changed files with 60 additions and 9 deletions
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69
drivers/gpu/drm/bridge/ti-sn65dsi86.c
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@ -348,12 +348,18 @@ static void ti_sn65dsi86_enable_comms(struct ti_sn65dsi86 *pdata,
* 200 ms. We'll assume that the panel driver will have the hardcoded
* delay in its prepare and always disable HPD.
*
* If HPD somehow makes sense on some future panel we'll have to
* change this to be conditional on someone specifying that HPD should
* be used.
* For DisplayPort bridge type, we need HPD. So we use the bridge type
* to conditionally disable HPD.
* NOTE: The bridge type is set in ti_sn_bridge_probe() but enable_comms()
* can be called before. So for DisplayPort, HPD will be enabled once
* bridge type is set. We are using bridge type instead of "no-hpd"
* property because it is not used properly in devicetree description
* and hence is unreliable.
*/
regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE,
HPD_DISABLE);
if (pdata->bridge.type != DRM_MODE_CONNECTOR_DisplayPort)
regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE,
HPD_DISABLE);
pdata->comms_enabled = true;
@ -1195,9 +1201,14 @@ static enum drm_connector_status ti_sn_bridge_detect(struct drm_bridge *bridge)
struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
int val = 0;
pm_runtime_get_sync(pdata->dev);
/*
* Runtime reference is grabbed in ti_sn_bridge_hpd_enable()
* as the chip won't report HPD just after being powered on.
* HPD_DEBOUNCED_STATE reflects correct state only after the
* debounce time (~100-400 ms).
*/
regmap_read(pdata->regmap, SN_HPD_DISABLE_REG, &val);
pm_runtime_put_autosuspend(pdata->dev);
return val & HPD_DEBOUNCED_STATE ? connector_status_connected
: connector_status_disconnected;
@ -1220,6 +1231,26 @@ static void ti_sn65dsi86_debugfs_init(struct drm_bridge *bridge, struct dentry *
debugfs_create_file("status", 0600, debugfs, pdata, &status_fops);
}
static void ti_sn_bridge_hpd_enable(struct drm_bridge *bridge)
{
struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
/*
* Device needs to be powered on before reading the HPD state
* for reliable hpd detection in ti_sn_bridge_detect() due to
* the high debounce time.
*/
pm_runtime_get_sync(pdata->dev);
}
static void ti_sn_bridge_hpd_disable(struct drm_bridge *bridge)
{
struct ti_sn65dsi86 *pdata = bridge_to_ti_sn65dsi86(bridge);
pm_runtime_put_autosuspend(pdata->dev);
}
static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
.attach = ti_sn_bridge_attach,
.detach = ti_sn_bridge_detach,
@ -1234,6 +1265,8 @@ static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
.debugfs_init = ti_sn65dsi86_debugfs_init,
.hpd_enable = ti_sn_bridge_hpd_enable,
.hpd_disable = ti_sn_bridge_hpd_disable,
};
static void ti_sn_bridge_parse_lanes(struct ti_sn65dsi86 *pdata,
@ -1321,8 +1354,26 @@ static int ti_sn_bridge_probe(struct auxiliary_device *adev,
pdata->bridge.type = pdata->next_bridge->type == DRM_MODE_CONNECTOR_DisplayPort
? DRM_MODE_CONNECTOR_DisplayPort : DRM_MODE_CONNECTOR_eDP;
if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort)
pdata->bridge.ops = DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_DETECT;
if (pdata->bridge.type == DRM_MODE_CONNECTOR_DisplayPort) {
pdata->bridge.ops = DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_DETECT |
DRM_BRIDGE_OP_HPD;
/*
* If comms were already enabled they would have been enabled
* with the wrong value of HPD_DISABLE. Update it now. Comms
* could be enabled if anyone is holding a pm_runtime reference
* (like if a GPIO is in use). Note that in most cases nobody
* is doing AUX channel xfers before the bridge is added so
* HPD doesn't _really_ matter then. The only exception is in
* the eDP case where the panel wants to read the EDID before
* the bridge is added. We always consistently have HPD disabled
* for eDP.
*/
mutex_lock(&pdata->comms_mutex);
if (pdata->comms_enabled)
regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG,
HPD_DISABLE, 0);
mutex_unlock(&pdata->comms_mutex);
};
drm_bridge_add(&pdata->bridge);