[PATCH v11 03/21] drm/bridge: synopsys: dw-dp: Fix error handling for DP link enablement

[Andy Yan]

Hello Sebastian,
At 2026-08-07 01:02:09, "Sebastian Reichel" <sebastian.reichel at collabora.com> wrote:
>dw_dp_link_disable() may be called in atomic mode disable even when
>dw_dp_link_enable() (or an earlier step) failed during atomic mode
>enable as there is no error tracking. This would result in broken PHY
>power state.
>
>This is fixed by introducing a new enabled state in the link structure
>to ensure the link disabling only happens if it has been properly
>enabled in the first place.
>
>The patch also adds missing error handling in dw_dp_link_enable()
>itself to ensure the link enablement becomes an atomic operation.
>
>Fixes: 86eecc3a9c2e ("drm/bridge: synopsys: Add DW DPTX Controller support library")
>Reported-by: Sashiko <sashiko-bot at kernel.org>

>Signed-off-by: Sebastian Reichel <sebastian.reichel at collabora.com>


  Acked-by: Andy Yan <andy.yan at rock-chips.com>

> drivers/gpu/drm/bridge/synopsys/dw-dp.c | 19 ++++++++++++++++++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>index d7945f7fe9f0..21d60e89126f 100644
>--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
>@@ -280,6 +280,7 @@ struct dw_dp_link {
> 	unsigned char revision;
> 	unsigned int rate;
> 	unsigned int lanes;
>+	bool enabled;
> 	u8 sink_count;
> 	u8 vsc_sdp_supported;
> 	struct dw_dp_link_caps caps;
>@@ -1615,6 +1616,9 @@ static void dw_dp_link_disable(struct dw_dp *dp)
> {
> 	struct dw_dp_link *link = &dp->link;
> 
>+	if (!link->enabled)
>+		return;
>+
> 	if (dw_dp_hpd_detect(dp))
> 		drm_dp_link_power_down(&dp->aux, dp->link.revision);
> 
>@@ -1624,6 +1628,7 @@ static void dw_dp_link_disable(struct dw_dp *dp)
> 
> 	link->train.clock_recovered = false;
> 	link->train.channel_equalized = false;
>+	link->enabled = false;
> }
> 
> static int dw_dp_link_enable(struct dw_dp *dp)
>@@ -1636,10 +1641,22 @@ static int dw_dp_link_enable(struct dw_dp *dp)
> 
> 	ret = drm_dp_link_power_up(&dp->aux, dp->link.revision);
> 	if (ret < 0)
>-		return ret;
>+		goto err_phy_power_off;
> 
> 	ret = dw_dp_link_train(dp);
>+	if (ret < 0)
>+		goto err_link_power_down;
>+
>+	dp->link.enabled = true;
> 
>+	return 0;
>+
>+err_link_power_down:
>+	drm_dp_link_power_down(&dp->aux, dp->link.revision);
>+	dw_dp_phy_xmit_enable(dp, 0);
>+
>+err_phy_power_off:
>+	phy_power_off(dp->phy);
> 	return ret;
> }
> 
>
>-- 
>2.53.0
>