Re: [v5,12/13] drm/ast: Implement polling for VGA and SIL164 connectors

[Sui Jingfeng <sui.jingfeng@linux.dev>]

Hi,


On 2024/3/20 17:34, Thomas Zimmermann wrote:
> Implement polling for VGA and SIL164 connectors. Set the flag
> DRM_CONNECTOR_POLL_DISCONNECT for each to detect the removal of the
> monitor cable. Implement struct drm_connector_helper_funcs.detect_ctx
> for each type of connector by testing for EDID data.
>
> The helper drm_connector_helper_detect_ctx() implements .detect_ctx()
> on top of the connector's DDC channel. The function can be used by
> other drivers as companion to drm_connector_helper_get_modes().
>
> v5:
> - share implementation in drm_connector_helper_detect_ctx() (Maxime)
> - test for DDC presence with drm_probe_ddc() (Maxime, Jani)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>


Yeah, previously, drm/ast only poll for the connected status.
Once connected, it never disconnected. This is fine for single
display pipe. But for two display pipes case, hot-plug is a core
functionality and absolutely necessary requirements.

Now that drm/ast becomes better than before:

Acked-by: Sui Jingfeng <sui.jingfeng@linux.dev>


> ---
>   drivers/gpu/drm/ast/ast_mode.c     |  6 ++++--
>   drivers/gpu/drm/drm_probe_helper.c | 29 +++++++++++++++++++++++++++++
>   include/drm/drm_probe_helper.h     |  3 +++
>   3 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index 71cc681d6188f..a42a0956c51de 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -1346,6 +1346,7 @@ static int ast_crtc_init(struct drm_device *dev)
>   
>   static const struct drm_connector_helper_funcs ast_vga_connector_helper_funcs = {
>   	.get_modes = drm_connector_helper_get_modes,
> +	.detect_ctx = drm_connector_helper_detect_ctx,
>   };
>   
>   static const struct drm_connector_funcs ast_vga_connector_funcs = {
> @@ -1379,7 +1380,7 @@ static int ast_vga_connector_init(struct drm_device *dev, struct drm_connector *
>   	connector->interlace_allowed = 0;
>   	connector->doublescan_allowed = 0;
>   
> -	connector->polled = DRM_CONNECTOR_POLL_CONNECT;
> +	connector->polled = DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT;
>   
>   	return 0;
>   }
> @@ -1414,6 +1415,7 @@ static int ast_vga_output_init(struct ast_device *ast)
>   
>   static const struct drm_connector_helper_funcs ast_sil164_connector_helper_funcs = {
>   	.get_modes = drm_connector_helper_get_modes,
> +	.detect_ctx = drm_connector_helper_detect_ctx,
>   };
>   
>   static const struct drm_connector_funcs ast_sil164_connector_funcs = {
> @@ -1447,7 +1449,7 @@ static int ast_sil164_connector_init(struct drm_device *dev, struct drm_connecto
>   	connector->interlace_allowed = 0;
>   	connector->doublescan_allowed = 0;
>   
> -	connector->polled = DRM_CONNECTOR_POLL_CONNECT;
> +	connector->polled = DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT;
>   
>   	return 0;
>   }
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 4d60cc810b577..b06dcc6c614e8 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -1272,3 +1272,32 @@ int drm_connector_helper_tv_get_modes(struct drm_connector *connector)
>   	return i;
>   }
>   EXPORT_SYMBOL(drm_connector_helper_tv_get_modes);
> +
> +/**
> + * drm_connector_helper_detect_ctx - Read EDID and detect connector status.
> + * @connector: The connector
> + * @ctx: Acquire context
> + * @force: Perform screen-destructive operations, if necessary
> + *
> + * Detects the connector status by reading the EDID using drm_probe_ddc(),
> + * which requires connector->ddc to be set. Returns connector_status_connected
> + * on success or connector_status_disconnected on failure.
> + *
> + * Returns:
> + * The connector status as defined by enum drm_connector_status.
> + */
> +int drm_connector_helper_detect_ctx(struct drm_connector *connector,
> +				    struct drm_modeset_acquire_ctx *ctx,
> +				    bool force)
> +{
> +	struct i2c_adapter *ddc = connector->ddc;
> +
> +	if (!ddc)
> +		return connector_status_unknown;
> +
> +	if (drm_probe_ddc(ddc))
> +		return connector_status_connected;
> +
> +	return connector_status_disconnected;
> +}
> +EXPORT_SYMBOL(drm_connector_helper_detect_ctx);
> diff --git a/include/drm/drm_probe_helper.h b/include/drm/drm_probe_helper.h
> index 62741a88796bb..031b044528c89 100644
> --- a/include/drm/drm_probe_helper.h
> +++ b/include/drm/drm_probe_helper.h
> @@ -37,4 +37,7 @@ int drm_connector_helper_get_modes_fixed(struct drm_connector *connector,
>   int drm_connector_helper_get_modes(struct drm_connector *connector);
>   int drm_connector_helper_tv_get_modes(struct drm_connector *connector);
>   
> +int drm_connector_helper_detect_ctx(struct drm_connector *connector,
> +				    struct drm_modeset_acquire_ctx *ctx,
> +				    bool force);
>   #endif

-- 
Best regards,
Sui