[PATCH v6 1/2] drm/ast: Add BMC virtual connector

[Jocelyn Falempe]

On 13/07/2023 15:41, Jocelyn Falempe wrote:
> Most aspeed devices have a BMC, which allows to remotely see the screen.
> Also in the common use case, those servers don't have a display connected.
> So add a Virtual connector, to reflect that even if no display is
> connected, the framebuffer can still be seen remotely.
> This prepares the work to implement a detect_ctx() for the Display port
> connector.
> 
> v4: call drm_add_modes_noedid() with 4096x4096 (Thomas Zimmermann)
>      remove useless struct field init to 0 (Thomas Zimmermann)
>      don't use drm_simple_encoder_init() (Thomas Zimmermann)
>      inline ast_bmc_connector_init() (Thomas Zimmermann)
> 
> Fixes: fae7d186403e ("drm/probe-helper: Default to 640x480 if no EDID on DP")
> Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
> ---
>   drivers/gpu/drm/ast/ast_drv.h  |  4 +++
>   drivers/gpu/drm/ast/ast_mode.c | 58 ++++++++++++++++++++++++++++++++++
>   2 files changed, 62 insertions(+)
> 
> diff --git a/drivers/gpu/drm/ast/ast_drv.h b/drivers/gpu/drm/ast/ast_drv.h
> index 3f6e0c984523..c9659e72002f 100644
> --- a/drivers/gpu/drm/ast/ast_drv.h
> +++ b/drivers/gpu/drm/ast/ast_drv.h
> @@ -214,6 +214,10 @@ struct ast_device {
>   			struct drm_encoder encoder;
>   			struct drm_connector connector;
>   		} astdp;
> +		struct {
> +			struct drm_encoder encoder;
> +			struct drm_connector connector;
> +		} bmc;
>   	} output;
>   
>   	bool support_wide_screen;
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index f711d592da52..1a8293162fec 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -1735,6 +1735,61 @@ static int ast_astdp_output_init(struct ast_device *ast)
>   	return 0;
>   }
>   
> +/*
> + * BMC virtual Connector
> + */
> +
> +static int ast_bmc_connector_helper_get_modes(struct drm_connector *connector)
> +{
> +	return drm_add_modes_noedid(connector, 4096, 4096);
> +}
> +
> +static const struct drm_connector_helper_funcs ast_bmc_connector_helper_funcs = {
> +	.get_modes = ast_bmc_connector_helper_get_modes,
> +};
> +
> +static const struct drm_connector_funcs ast_bmc_connector_funcs = {
> +	.reset = drm_atomic_helper_connector_reset,
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.destroy = drm_connector_cleanup,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static const struct drm_encoder_funcs ast_bmc_encoder_funcs = {
> +	.destroy = drm_encoder_cleanup,
> +};
> +
> +static int ast_bmc_output_init(struct ast_device *ast)
> +{
> +	struct drm_device *dev = &ast->base;
> +	struct drm_crtc *crtc = &ast->crtc;
> +	struct drm_encoder *encoder = &ast->output.bmc.encoder;
> +	struct drm_connector *connector = &ast->output.bmc.connector;
> +	int ret;
> +
> +
> +	ret = drm_encoder_init(dev, encoder,
> +				&ast_bmc_encoder_funcs,
> +				DRM_MODE_ENCODER_VIRTUAL, "ast_bmc");
> +	if (ret)
> +		return ret;
> +	encoder->possible_crtcs = drm_crtc_mask(crtc);
> +
> +	ret = drm_connector_init(dev, connector, &ast_bmc_connector_funcs,
> +				 DRM_MODE_CONNECTOR_VIRTUAL);
> +	if (ret)
> +		return ret;
> +
> +	drm_connector_helper_add(connector, &ast_bmc_connector_helper_funcs);
> +
> +	ret = drm_connector_attach_encoder(connector, encoder);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>   /*
>    * Mode config
>    */
> @@ -1842,6 +1897,9 @@ int ast_mode_config_init(struct ast_device *ast)
>   		if (ret)
>   			return ret;
>   	}
> +	ret = ast_bmc_output_init(ast);
> +	if (ret)
> +		return ret;
>   
>   	drm_mode_config_reset(dev);
>   
> 
> base-commit: b32d5a51f3c21843011d68a58e6ac0b897bce9f2


I'm missing a review on this patch. The VGA CRD0[7] register check 
doesn't work on my server, so I'm adding the BMC virtual connector for 
all aspeed hardware, but as discussed, it shouldn't have a negative impact.

Thanks,

-- 

Jocelyn