@@ -1355,6 +1355,71 @@ struct drm_mode_closefb {
__u32 pad;
};
+/**
+ * enum drm_mode_histogram
+ *
+ * @DRM_MODE_HISTOGRAM_HSV_MAX_RGB:
+ * Maximum resolution at present 10k, 10240x4320 = 44236800
+ * can be denoted in 25bits. With an additional 7 bits in buffer each bin
+ * can be a u32 value.
+ * For SDL, Maximum value of max(RGB) is 255, so max 255 bins.
+ * If the most significant 5 bits are considered, then bins = 2^5
+ * will be 32 bins.
+ * For HDR, maximum value of max(RGB) is 65535, so max 65535 bins.
+ * For illustration consider a full RED image of 10k resolution considering all
+ * 8 bits histogram would look like hist[255] = {0,0,....44236800} with SDR
+ * plane similarly with HDR the same would look like hist[65535] =
+ * {0,0,0,....44236800}
+ */
+enum drm_mode_histogram {
+ DRM_MODE_HISTOGRAM_HSV_MAX_RGB = 0x01,
+};
+
+/**
+ * struct drm_histogram_caps
+ *
+ * @histogram_mode: histogram generation modes, defined in the
+ * enum drm_mode_histogram
+ * @bins_count: number of bins for a chosen histogram mode. For illustration
+ * refer the above defined histogram mode.
+ */
+struct drm_histogram_caps {
+ __u32 histogram_mode;
+ __u32 bins_count;
+};
+
+/**
+ * struct drm_histogram_config
+ *
+ * @hist_mode_data: address to the histogram mode specific data if any
+ * @nr_hist_mode_data: number of elements pointed by the address in
+ * hist_mode_data
+ * @hist_mode: histogram mode(HSV max(RGB), RGB, LUMA etc)
+ * @enable: flag to enable/disable histogram
+ */
+struct drm_histogram_config {
+ __u64 hist_mode_data;
+ __u32 nr_hist_mode_data;
+ enum drm_mode_histogram hist_mode;
+ bool enable;
+};
+
+/**
+ * struct drm_histogram
+ *
+ * @config: histogram configuration data pointed by struct drm_histogram_config
+ * @data_ptr: pointer to the array of histogram.
+ * Histogram is an array of bins. Data format for each bin depends
+ * on the histogram mode. Refer to the above histogram modes for
+ * more information.
+ * @nr_elements: number of bins in the histogram.
+ */
+struct drm_histogram {
+ struct drm_histogram_config config;
+ __u64 data_ptr;
+ __u32 nr_elements;
+};
+
#if defined(__cplusplus)
}
#endif
Display Histogram is an array of bins and can be generated in many ways referred to as modes. Ex: HSV max(RGB), Wighted RGB etc. Understanding the histogram data format(Ex: HSV max(RGB)) Histogram is just the pixel count. For a maximum resolution of 10k (10240 x 4320 = 44236800) 25 bits should be sufficient to represent this along with a buffer of 7 bits(future use) u32 is being considered. max(RGB) can be 255 i.e 0xFF 8 bit, considering the most significant 5 bits, hence 32 bins. Below mentioned algorithm illustrates the histogram generation in hardware. hist[32] = {0}; for (i = 0; i < resolution; i++) { bin = max(RGB[i]); bin = bin >> 3; /* consider the most significant bits */ hist[bin]++; } If the entire image is Red color then max(255,0,0) is 255 so the pixel count of each pixels will be placed in the last bin. Hence except hist[31] all other bins will have a value zero. Generated histogram in this case would be hist[32] = {0,0,....44236800} Description of the structures, properties defined are documented in the header file include/uapi/drm/drm_mode.h v8: Added doc for HDR planes, removed reserved variables (Dmitry) Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com> --- include/uapi/drm/drm_mode.h | 65 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+)