[libcamera-devel] [PATCH] Add option to list displays

[Laurent Pinchart]

Hi Eric,

Thank you for the patch.

On Wed, Oct 27, 2021 at 11:04:41AM +0100, Eric Curtin wrote:
> xrand --query isn't always available and does not always display all
> conneted connectors.

Stupid questions, couldn't connectors also be listed through sysfs ?

for conn in /sys/class/drm/card*-* ; do status=$(cat $conn/status) ; if [ $status == connected ] ; then echo $conn ; fi ; done

I'm not opposed to adding this feature to the cam application, but I
wonder if it really belongs here, especially if we consider that a next
step would be to print supported modes.

> Signed-off-by: Eric Curtin <ecurtin at redhat.com>
> ---
>  src/cam/main.cpp | 31 ++++++++++++++++++++++++++-----
>  src/cam/main.h   |  3 +++
>  2 files changed, 29 insertions(+), 5 deletions(-)
> 
> diff --git a/src/cam/main.cpp b/src/cam/main.cpp
> index c7f664b9..319cbf4d 100644
> --- a/src/cam/main.cpp
> +++ b/src/cam/main.cpp
> @@ -15,6 +15,11 @@
>  #include <libcamera/property_ids.h>
>  
>  #include "camera_session.h"
> +
> +#ifdef HAVE_KMS
> +#include "drm.h"
> +#endif
> +
>  #include "event_loop.h"
>  #include "main.h"
>  #include "options.h"
> @@ -137,6 +142,7 @@ int CamApp::parseOptions(int argc, char *argv[])
>  			 "Display viewfinder through DRM/KMS on specified connector",
>  			 "display", ArgumentOptional, "connector", false,
>  			 OptCamera);
> +	parser.addOption(OptListDisplays, OptionNone, "List all displays", "list-displays");
>  #endif
>  	parser.addOption(OptFile, OptionString,
>  			 "Write captured frames to disk\n"
> @@ -202,7 +208,22 @@ int CamApp::run()
>  		}
>  	}
>  
> -	/* 2. Create the camera sessions. */
> +#ifdef HAVE_KMS
> +	/* 2. List all displays. */
> +	if (options_.isSet(OptListDisplays)) {
> +		std::cout << "Available displays:" << std::endl;
> +
> +		DRM::Device dev;
> +		dev.init();

As Umang mentioned, errors should be checked.

> +		for (const DRM::Connector &conn : dev.connectors()) {
> +			if (conn.status() == DRM::Connector::Connected) {
> +				std::cout << conn.name() << std::endl;
> +			}

No need for curly braces in the inner if.

> +		}
> +	}
> +#endif
> +
> +	/* 3. Create the camera sessions. */
>  	std::vector<std::unique_ptr<CameraSession>> sessions;
>  
>  	if (options_.isSet(OptCamera)) {
> @@ -229,7 +250,7 @@ int CamApp::run()
>  		}
>  	}
>  
> -	/* 3. Print camera information. */
> +	/* 4. Print camera information. */
>  	if (options_.isSet(OptListControls) ||
>  	    options_.isSet(OptListProperties) ||
>  	    options_.isSet(OptInfo)) {
> @@ -243,7 +264,7 @@ int CamApp::run()
>  		}
>  	}
>  
> -	/* 4. Start capture. */
> +	/* 5. Start capture. */
>  	for (const auto &session : sessions) {
>  		if (!session->options().isSet(OptCapture))
>  			continue;
> @@ -257,7 +278,7 @@ int CamApp::run()
>  		loopUsers_++;
>  	}
>  
> -	/* 5. Enable hotplug monitoring. */
> +	/* 6. Enable hotplug monitoring. */
>  	if (options_.isSet(OptMonitor)) {
>  		std::cout << "Monitoring new hotplug and unplug events" << std::endl;
>  		std::cout << "Press Ctrl-C to interrupt" << std::endl;
> @@ -271,7 +292,7 @@ int CamApp::run()
>  	if (loopUsers_)
>  		loop_.exec();
>  
> -	/* 6. Stop capture. */
> +	/* 7. Stop capture. */
>  	for (const auto &session : sessions) {
>  		if (!session->options().isSet(OptCapture))
>  			continue;
> diff --git a/src/cam/main.h b/src/cam/main.h
> index 1c2fab76..72050d27 100644
> --- a/src/cam/main.h
> +++ b/src/cam/main.h
> @@ -21,6 +21,9 @@ enum {
>  	OptListControls = 256,
>  	OptStrictFormats = 257,
>  	OptMetadata = 258,
> +#ifdef HAVE_KMS
> +	OptListDisplays = 259
> +#endif
>  };
>  
>  #endif /* __CAM_MAIN_H__ */

-- 
Regards,

Laurent Pinchart