[media] gspca - sn9c20x: Add the JPEG compression quality control

The JPEG compression quality was hardcoded to 95%. This value was too big,
raising often buffer overflows.
This quality is now 80% by default and is settable.

Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 37 insertions, 4 deletions

diff --git a/drivers/media/video/gspca/sn9c20x.c b/drivers/media/video/gspca/sn9c20x.c
index 97c653f9f983..0894a3d2c336 100644
--- a/drivers/media/video/gspca/sn9c20x.c
+++ b/drivers/media/video/gspca/sn9c20x.c
@@ -79,6 +79,7 @@ enum e_ctrl {
         EXPOSURE,
         GAIN,
         AUTOGAIN,
+        QUALITY,
         NCTRLS          /* number of controls */
 };
 
@@ -88,6 +89,8 @@ struct sd {
 
         struct gspca_ctrl ctrls[NCTRLS];
 
+        u8 fmt;                         /* (used for JPEG QTAB update */
+
 #define MIN_AVG_LUM 80
 #define MAX_AVG_LUM 130
         atomic_t avg_lum;
@@ -101,7 +104,6 @@ struct sd {
         u8 vstart;
 
         u8 jpeg_hdr[JPEG_HDR_SZ];
-        u8 quality;
 
         u8 flags;
 };
@@ -162,6 +164,7 @@ static void set_redblue(struct gspca_dev *gspca_dev);
 static void set_hvflip(struct gspca_dev *gspca_dev);
 static void set_exposure(struct gspca_dev *gspca_dev);
 static void set_gain(struct gspca_dev *gspca_dev);
+static void set_quality(struct gspca_dev *gspca_dev);
 
 static const struct ctrl sd_ctrls[NCTRLS] = {
 [BRIGHTNESS] = {
@@ -307,6 +310,21 @@ static const struct ctrl sd_ctrls[NCTRLS] = {
                 .default_value = 1,
             },
         },
+[QUALITY] = {
+            {
+                .id      = V4L2_CID_JPEG_COMPRESSION_QUALITY,
+                .type    = V4L2_CTRL_TYPE_INTEGER,
+                .name    = "Compression Quality",
+#define QUALITY_MIN 50
+#define QUALITY_MAX 90
+#define QUALITY_DEF 80
+                .minimum = QUALITY_MIN,
+                .maximum = QUALITY_MAX,
+                .step    = 1,
+                .default_value = QUALITY_DEF,
+            },
+            .set_control = set_quality
+        },
 };
 
 static const struct v4l2_pix_format vga_mode[] = {
@@ -1732,6 +1750,21 @@ static void set_gain(struct gspca_dev *gspca_dev)
         i2c_w(gspca_dev, gain);
 }
 
+static void set_quality(struct gspca_dev *gspca_dev)
+{
+        struct sd *sd = (struct sd *) gspca_dev;
+
+        jpeg_set_qual(sd->jpeg_hdr, sd->ctrls[QUALITY].val);
+        reg_w1(gspca_dev, 0x1061, 0x01);        /* stop transfer */
+        reg_w1(gspca_dev, 0x10e0, sd->fmt | 0x20); /* write QTAB */
+        reg_w(gspca_dev, 0x1100, &sd->jpeg_hdr[JPEG_QT0_OFFSET], 64);
+        reg_w(gspca_dev, 0x1140, &sd->jpeg_hdr[JPEG_QT1_OFFSET], 64);
+        reg_w1(gspca_dev, 0x1061, 0x03);        /* restart transfer */
+        reg_w1(gspca_dev, 0x10e0, sd->fmt);
+        sd->fmt ^= 0x0c;                        /* invert QTAB use + write */
+        reg_w1(gspca_dev, 0x10e0, sd->fmt);
+}
+
 #ifdef CONFIG_VIDEO_ADV_DEBUG
 static int sd_dbg_g_register(struct gspca_dev *gspca_dev,
                         struct v4l2_dbg_register *reg)
@@ -1846,7 +1879,6 @@ static int sd_config(struct gspca_dev *gspca_dev,
 
         gspca_dev->cam.ctrls = sd->ctrls;
 
-        sd->quality = 95;
 
         return 0;
 }
@@ -2058,14 +2090,15 @@ static int sd_start(struct gspca_dev *gspca_dev)
 
         jpeg_define(sd->jpeg_hdr, height, width,
                         0x21);
-        jpeg_set_qual(sd->jpeg_hdr, sd->quality);
+        jpeg_set_qual(sd->jpeg_hdr, sd->ctrls[QUALITY].val);
 
         if (mode & MODE_RAW)
                 fmt = 0x2d;
         else if (mode & MODE_JPEG)
-                fmt = 0x2c;
+                fmt = 0x24;
         else
                 fmt = 0x2f;     /* YUV 420 */
+        sd->fmt = fmt;
 
         switch (mode & SCALE_MASK) {
         case SCALE_1280x1024: