Re: [Intel-gfx] [PATCH v2 1/3] drm/edid: Add drm_edid_get_monitor_name()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 07 Apr 2016, Jim Bride <jim.bride@linux.intel.com> wrote:
> In order to include monitor name information in debugfs
> output we needed to add a function that would extract the
> monitor name from the EDID, and that function needed to
> reside in the file  where the rest of the EDID helper
> functions are implemented.
>
> v2: Refactor to have drm_edid_get_monitor_name() and drm_edid_to_eld()
>     use a common helper function to extract the monitor name from the
>     edid. [Jani] + rebase.
>
> cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Jim Bride <jim.bride@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 50 +++++++++++++++++++++++++++++++++++++---------
>  include/drm/drm_crtc.h     |  2 ++
>  2 files changed, 43 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 558ef9f..daf53df 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3293,6 +3293,45 @@ monitor_name(struct detailed_timing *t, void *data)
>  		*(u8 **)data = t->data.other_data.data.str.str;
>  }
>  
> +static int get_monitor_name(struct edid *edid, char name[13])
> +{
> +	char *edid_name = NULL;
> +	int mnl;
> +
> +	if (!edid || !name)
> +		return 0;
> +
> +	drm_for_each_detailed_block((u8 *)edid, monitor_name, &edid_name);
> +	for (mnl = 0; edid_name && mnl < 13; mnl++) {
> +		if (edid_name[mnl] == 0x0a)
> +			break;
> +
> +		name[mnl] = edid_name[mnl];
> +	}
> +
> +	return mnl;
> +}
> +
> +/**
> + * drm_edid_get_monitor_name - fetch the monitor name from the edid
> + * @edid: monitor EDID information
> + * @name: pointer to a character array to hold the name of the monitor
> + * @bufsize: The size of the name buffer (should be at least 13 chars.)
> + *
> + */
> +void drm_edid_get_monitor_name(struct edid *edid, char *name, int bufsize)
> +{
> +	int name_length = -1;
> +
> +	if (bufsize < 13)
> +		return;
> +
> +	name_length = get_monitor_name(edid, name);
> +	if (name_length)
> +		name[name_length] = '\0';

I was thinking something along the lines of:

	char buf[13];
	int len;

	if (bufsize <= 0)
		return;

	len = min(get_monitor_name(edid, buf), bufsize - 1);
	memcpy(name, buf, len);
	name[len] = '\0';

BR,
Jani.

> +}
> +EXPORT_SYMBOL(drm_edid_get_monitor_name);
> +
>  /**
>   * drm_edid_to_eld - build ELD from EDID
>   * @connector: connector corresponding to the HDMI/DP sink
> @@ -3306,7 +3345,6 @@ void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
>  {
>  	uint8_t *eld = connector->eld;
>  	u8 *cea;
> -	u8 *name;
>  	u8 *db;
>  	int total_sad_count = 0;
>  	int mnl;
> @@ -3320,14 +3358,8 @@ void drm_edid_to_eld(struct drm_connector *connector, struct edid *edid)
>  		return;
>  	}
>  
> -	name = NULL;
> -	drm_for_each_detailed_block((u8 *)edid, monitor_name, &name);
> -	/* max: 13 bytes EDID, 16 bytes ELD */
> -	for (mnl = 0; name && mnl < 13; mnl++) {
> -		if (name[mnl] == 0x0a)
> -			break;
> -		eld[20 + mnl] = name[mnl];
> -	}
> +	mnl = get_monitor_name(edid, eld + 20);
> +
>  	eld[4] = (cea[1] << 5) | mnl;
>  	DRM_DEBUG_KMS("ELD monitor %s\n", eld + 20);
>  
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 8cb377c..6d46842 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -2500,6 +2500,8 @@ extern int drm_edid_header_is_valid(const u8 *raw_edid);
>  extern bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid,
>  				 bool *edid_corrupt);
>  extern bool drm_edid_is_valid(struct edid *edid);
> +extern void drm_edid_get_monitor_name(struct edid *edid, char *name,
> +				      int buflen);
>  
>  extern struct drm_tile_group *drm_mode_create_tile_group(struct drm_device *dev,
>  							 char topology[8]);

-- 
Jani Nikula, Intel Open Source Technology Center
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