Re: drm/atmel-hlcdc: connector type & fbdev mode settings

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Wed, 31 Aug 2016 11:29:53 +0900
Hyung Jin Jung <realbright@lgcns.com> wrote:

> According to Atmel's guideline... http://www.at91.com/linux4sam/bin/view/Linux4SAM/UsingAtmelDRMDriver
> 
> the "fbdev emulation mode" could be set from kernel command line (LVDS-1:...)
> however, driver register it as DRM_MODE_CONNECTOR_Unknown connector.

Just adapt the command line with Unknown-1:...

> 
> Actually we using sama5d3x with LVDS cable so that below patch would be correct.

No it wouldn't. The sama5 SoC is providing a raw RGB interface, so if
you really have an LVDS interface on your board this means you have a
bridge in the middle. This bridge should be represented in the DT, and
attached to a driver in the kernel.

> But I don't know the other case such as HDMI, composite... 
> 
> Do we need to consider using DT or auto-detection??
> 
> Signed-off-by: HyungJin Jung <realbright@lgcns.com>
> ---
>  drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
> index 6119b50..da97efe
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
> @@ -208,7 +208,7 @@ static int atmel_hlcdc_attach_endpoint(struct drm_device *dev,
>  				&atmel_hlcdc_panel_connector_helper_funcs);
>  		ret = drm_connector_init(dev, &output->connector,
>  					 &atmel_hlcdc_panel_connector_funcs,
> -					 DRM_MODE_CONNECTOR_Unknown);
> +					 DRM_MODE_CONNECTOR_LVDS);
>  		if (ret)
>  			goto err_encoder_cleanup;
>