Re: [PATCH 1/5] drm/ast: astdp: Wake up during connector status detection

[Jocelyn Falempe <jfalempe@xxxxxxxxxx>]

On 17/07/2024 16:24, Thomas Zimmermann wrote:
> Power up the ASTDP connector for connection status detection if the
> connector is not active. Keep it powered if a display is attached.
>
> This fixes a bug where the connector does not come back after
> disconnecting the display. The encoder's atomic_disable turns off
> power on the physical connector. Further HPD reads will fail,
> thus preventing the driver from detecting re-connected displays.
>
> For connectors that are actively used, only test the HPD flag without
> touching power.

Thanks, it looks good to me.

Reviewed-by: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
> Fixes: f81bb0ac7872 ("drm/ast: report connection status on Display Port.")
> Cc: Jocelyn Falempe <jfalempe@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: Dave Airlie <airlied@xxxxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: <stable@xxxxxxxxxxxxxxx> # v6.6+
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> ---
>   drivers/gpu/drm/ast/ast_dp.c   |  7 +++++++
>   drivers/gpu/drm/ast/ast_drv.h  |  1 +
>   drivers/gpu/drm/ast/ast_mode.c | 29 +++++++++++++++++++++++++++--
>   3 files changed, 35 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
> index 1e9259416980..e6c7f0d64e99 100644
> --- a/drivers/gpu/drm/ast/ast_dp.c
> +++ b/drivers/gpu/drm/ast/ast_dp.c
> @@ -158,7 +158,14 @@ void ast_dp_launch(struct drm_device *dev)
>   			       ASTDP_HOST_EDID_READ_DONE);
>   }
>   
> +bool ast_dp_power_is_on(struct ast_device *ast)
> +{
> +	u8 vgacre3;
> +
> +	vgacre3 = ast_get_index_reg(ast, AST_IO_VGACRI, 0xe3);
>   
> +	return !(vgacre3 & AST_DP_PHY_SLEEP);
> +}
>   
>   void ast_dp_power_on_off(struct drm_device *dev, bool on)
>   {
> diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
> index ba3d86973995..47bab5596c16 100644
> --- a/drivers/gpu/drm/ast/ast_drv.h
> +++ b/drivers/gpu/drm/ast/ast_drv.h
> @@ -472,6 +472,7 @@ void ast_init_3rdtx(struct drm_device *dev);
>   bool ast_astdp_is_connected(struct ast_device *ast);
>   int ast_astdp_read_edid(struct drm_device *dev, u8 *ediddata);
>   void ast_dp_launch(struct drm_device *dev);
> +bool ast_dp_power_is_on(struct ast_device *ast);
>   void ast_dp_power_on_off(struct drm_device *dev, bool no);
>   void ast_dp_set_on_off(struct drm_device *dev, bool no);
>   void ast_dp_set_mode(struct drm_crtc *crtc, struct ast_vbios_mode_info *vbios_mode);
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index dc8f639e82fd..049ee1477c33 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -28,6 +28,7 @@
>    * Authors: Dave Airlie <airlied@xxxxxxxxxx>
>    */
>   
> +#include <linux/delay.h>
>   #include <linux/export.h>
>   #include <linux/pci.h>
>   
> @@ -1687,11 +1688,35 @@ static int ast_astdp_connector_helper_detect_ctx(struct drm_connector *connector
>   						 struct drm_modeset_acquire_ctx *ctx,
>   						 bool force)
>   {
> +	struct drm_device *dev = connector->dev;
>   	struct ast_device *ast = to_ast_device(connector->dev);
> +	enum drm_connector_status status = connector_status_disconnected;
> +	struct drm_connector_state *connector_state = connector->state;
> +	bool is_active = false;
> +
> +	mutex_lock(&ast->modeset_lock);
> +
> +	if (connector_state && connector_state->crtc) {
> +		struct drm_crtc_state *crtc_state = connector_state->crtc->state;
> +
> +		if (crtc_state && crtc_state->active)
> +			is_active = true;
> +	}
> +
> +	if (!is_active && !ast_dp_power_is_on(ast)) {
> +		ast_dp_power_on_off(dev, true);
> +		msleep(50);
> +	}
>   
>   	if (ast_astdp_is_connected(ast))
> -		return connector_status_connected;
> -	return connector_status_disconnected;
> +		status = connector_status_connected;
> +
> +	if (!is_active && status == connector_status_disconnected)
> +		ast_dp_power_on_off(dev, false);
> +
> +	mutex_unlock(&ast->modeset_lock);
> +
> +	return status;
>   }
>   
>   static const struct drm_connector_helper_funcs ast_astdp_connector_helper_funcs = {