Re: [PATCH i-g-t 2/4] lib/igt_kms: add helpers to enable/disable force joiner

["Modem, Bhanuprakash" <bhanuprakash.modem@intel.com>]

Hi Kunal,

On 03-03-2024 10:52 pm, Kunal Joshi wrote:
> add helped to enable/disable force joiner and for
> checking current state enabled/disabled
> 
> Cc: Karthik B S <karthik.b.s@intel.com>
> Cc: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
> Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
> ---
>   lib/igt_kms.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>   lib/igt_kms.h |  2 ++
>   2 files changed, 50 insertions(+)
> 
> diff --git a/lib/igt_kms.c b/lib/igt_kms.c
> index 89956b9d5..e6952f56a 100644
> --- a/lib/igt_kms.c
> +++ b/lib/igt_kms.c
> @@ -6242,6 +6242,54 @@ bool igt_check_bigjoiner_support(igt_display_t *display)
>   	return true;
>   }
>   
> +/**
> + * Checks if the force big joiner is enabled for a specific connector.
> + *
> + * @param drmfd The file descriptor of the DRM device.
> + * @param connector_name The name of the connector.
> + * Returns:
> + *  1 if the force big joiner is enabled, 0 if disabled, and -1 on error.
> + */
> +int igt_check_force_bigjoiner_status(int drmfd, char *connector_name)
> +{
> +	char buf[512];
> +	int debugfs_fd, ret;
> +
> +	debugfs_fd = igt_debugfs_connector_dir(drmfd, connector_name, O_RDONLY);

We must guard "debugfs_fd" with igt_assert() or igt_require().

> +	ret = igt_debugfs_simple_read(debugfs_fd, "i915_bigjoiner_force_enable",
> +								  buf, sizeof(buf));
> +	if (ret < 0) {
> +		igt_info("Could not read debugfs %s\n",
> +				 strerror(-ret));
> +		return -1;
> +	}
> +	if (strstr(buf, "Bigjoiner enable: 1"))
> +		return 1;
> +	else if (strstr(buf, "Bigjoiner enable: 0"))
> +		return 0;
> +	else
> +		return -1;
> +}
> +
> +/**
> + * Forces the enable/disable state of big joiner for a specific connector.
> + *
> + * @param drmfd The file descriptor of the DRM device.
> + * @param connector_name The name of the connector.
> + * @param enable The desired state of big joiner (true for enable, false for disable).
> + * Returns:
> + *  >=0 on success, otherwise an error code.

IMHO, let's make return value as bool. Return True if write success else 
False.

> + */
> +int igt_force_bigjoiner_enable(int drmfd, char *connector_name, bool enable)
> +{
> +	int debugfs_fd, ret;
> +
> +	debugfs_fd = igt_debugfs_connector_dir(drmfd, connector_name, O_DIRECTORY);
----------------------------------------------------------------------^
This could be O_RDWR or O_WRONLY?

- Bhanu

> +	ret = igt_sysfs_write(debugfs_fd, "i915_bigjoiner_force_enable", enable ? "1" : "0", 1);
> +	close(debugfs_fd);
> +	return ret;
> +}
> +
>   /**
>    * igt_parse_mode_string:
>    * @mode_string: modeline string
> diff --git a/lib/igt_kms.h b/lib/igt_kms.h
> index bab8487d3..b28022db4 100644
> --- a/lib/igt_kms.h
> +++ b/lib/igt_kms.h
> @@ -1215,6 +1215,8 @@ bool igt_bigjoiner_possible(drmModeModeInfo *mode, int max_dotclock);
>   bool bigjoiner_mode_found(int drm_fd, drmModeConnector *connector,
>   			  int max_dotclock);
>   bool igt_check_bigjoiner_support(igt_display_t *display);
> +int igt_check_force_bigjoiner_status(int drmfd, char *connector_name);
> +int igt_force_bigjoiner_enable(int drmfd, char *connector_name, bool enable);
>   bool igt_parse_mode_string(const char *mode_string, drmModeModeInfo *mode);
>   bool intel_pipe_output_combo_valid(igt_display_t *display);
>   bool igt_check_output_is_dp_mst(igt_output_t *output);