[PATCH v7 1/5] media: rkisp1: uapi: change hist_bins array type from __u16 to __u32

[Dafna Hirschfeld]

Each entry in the array is a 20 bits value composed of 16
bits unsigned integer and 4 bits fractional part. So the
type should change to __u32.
In addition add a documentation of how the measurements
are done.

Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld at collabora.com>
---
 include/uapi/linux/rkisp1-config.h | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
index 6e449e784260..f75f8d698fb4 100644
--- a/include/uapi/linux/rkisp1-config.h
+++ b/include/uapi/linux/rkisp1-config.h
@@ -844,13 +844,17 @@ struct rkisp1_cif_isp_af_stat {
 /**
  * struct rkisp1_cif_isp_hist_stat - statistics histogram data
  *
- * @hist_bins: measured bin counters
+ * @hist_bins: measured bin counters. Each bin is a 20 bits unsigned fixed point type.
+ *	       Bits 0-4 are the fractional part and bits 5-19 are the integer part.
  *
- * Measurement window divided into 25 sub-windows, set
- * with ISP_HIST_XXX
+ * The window of the measurements area is divided to 5x5 sub-windows. The histogram
+ * is then computed for each sub-window independently and the final result is a weighted
+ * average of the histogram measurements on all sub-windows.
+ * The window of the measurements area and the weight of each sub-window are configurable
+ * using struct @rkisp1_cif_isp_hst_config.
  */
 struct rkisp1_cif_isp_hist_stat {
-	__u16 hist_bins[RKISP1_CIF_ISP_HIST_BIN_N_MAX];
+	__u32 hist_bins[RKISP1_CIF_ISP_HIST_BIN_N_MAX];
 };
 
 /**
-- 
2.17.1