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Commit bf2a2202 authored by Hans de Goede's avatar Hans de Goede Committed by Mauro Carvalho Chehab
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V4L/DVB (8870): gspca: Fix dark room problem with sonixb. 



When using the sonixb driver in a dark room and given that the autoexposure
algorithm starts with a setting most suitable for daylight, the picture
produced by the cam may actually be 100% black leading to a avg_lum value of 0,
so an avg_lum value of 0 does not always signal an exposure settings change
(which it normally does). This patch adds a check for the really black image
case and stops dropping all frames as invalid in this case.

Signed-off-by: default avatarHans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: default avatarJean-Francois Moine <moinejf@free.fr>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
parent a94a5086

drivers/media/video/gspca/sonixb.c

+12 −2
Original line number Diff line number Diff line
@@ -52,6 +52,7 @@ MODULE_LICENSE("GPL"); 
struct sd {

	struct gspca_dev gspca_dev;	/* !! must be the first item */

	atomic_t avg_lum;

	int prev_avg_lum;



	unsigned char gain;

	unsigned char exposure;
@@ -1022,10 +1023,19 @@ static void sd_pkt_scan(struct gspca_dev *gspca_dev, 
				} else {

					lum = data[i + 8] + (data[i + 9] << 8);

				}

				if (lum == 0) {

				/* When exposure changes midway a frame we

				   get a lum of 0 in this case drop 2 frames

				   as the frames directly after an exposure

				   change have an unstable image. Sometimes lum

				   *really* is 0 (cam used in low light with

				   low exposure setting), so do not drop frames

				   if the previous lum was 0 too. */

				if (lum == 0 && sd->prev_avg_lum != 0) {

					lum = -1;

					sd->frames_to_drop = 2;

				}

					sd->prev_avg_lum = 0;

				} else

					sd->prev_avg_lum = lum;

				atomic_set(&sd->avg_lum, lum);



				if (sd->frames_to_drop) {