33  * Three gain stages
35  * 0x007F: low gain bits
36  * 0x0080: medium gain bit
37  * 0x0100: high gain bit
38  * gain = enable * (1 + regH) * (1 + regM) * z * regL
40  * Gain implementation
43  * Gain does not vary with resolution (checked 640x480 vs 1600x1200)
48  * Gain,   GTOP,   B,	  R,	  GBOT
71  * However, V4L expects a main gain channel + R and B balance
75  * Converted using gain model turns out to be quite linear:
76  * Gain, GTOP, B, R, GBOT
89  * Maximum gain is 0x7FF * 2 * 2 => 0x1FFC (8188)
90  * or about 13 effective bits of gain
93  * limit the gain until have a reason to go higher
94  * Solution: gain clipped and warning emitted
144 	V4L supports master gain which is referenced to G1/G2 and supplies
280 	gspca_dbg(gspca_dev, D_STREAM, "gain G1/G2 (0x%04X): 0x%04X (src 0x%04X)\n\n",  in setggain()
289 		u16 gain, u16 global_gain)  in setbgain()  argument
294 		((u32)global_gain) * gain / GAIN_MAX;  in setbgain()
301 	gspca_dbg(gspca_dev, D_STREAM, "gain B (0x%04X): 0x%04X w/ source 0x%04X\n\n",  in setbgain()
302 		  REG_BLUE_GAIN, normalized, gain);  in setbgain()
308 		u16 gain, u16 global_gain)  in setrgain()  argument
313 		((u32)global_gain) * gain / GAIN_MAX;  in setrgain()
315 		gspca_dbg(gspca_dev, D_STREAM, "Truncating gain 0x%04X w/ value 0x%04X\n\n",  in setrgain()
320 	gspca_dbg(gspca_dev, D_STREAM, "gain R (0x%04X): 0x%04X w / source 0x%04X\n\n",  in setrgain()
321 		  REG_RED_GAIN, normalized, gain);  in setrgain()
601 		/* gspca_dev->gain automatically updated */  in sd_s_ctrl()
602 		setggain(gspca_dev, gspca_dev->gain->val);  in sd_s_ctrl()
606 		setbgain(gspca_dev, sd->blue->val, gspca_dev->gain->val);  in sd_s_ctrl()
610 		setrgain(gspca_dev, sd->red->val, gspca_dev->gain->val);  in sd_s_ctrl()
632 	gspca_dev->gain = v4l2_ctrl_new_std(hdl, &sd_ctrl_ops,  in sd_init_controls()