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V4L/DVB (13179): gspca_ov519: cache sensor regs to avoid unnecessary slow i2c reads / writes

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Cache sensor regs to avoid unnecessary slow i2c reads / writes, this speeds
up sd_start a bit with most bridges and a lot (from 5 seconds down to 0.3
seconds) with W996xCF cams, as this avoids very slow bit bang IO over
USB i2c reads.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Hans de Goede 2009-10-16 07:42:53 -03:00 committed by Mauro Carvalho Chehab
parent a511ba9476
commit fb1f902060
1 changed files with 43 additions and 10 deletions
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53
drivers/media/video/gspca/ov519.c
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@ -103,6 +103,7 @@ struct sd {
u8 sensor_addr;
int sensor_width;
int sensor_height;
int sensor_reg_cache[256];
};
/* Note this is a bit of a hack, but the w9968cf driver needs the code for all
@ -2210,38 +2211,70 @@ static int ovfx2_i2c_r(struct sd *sd, __u8 reg)
static int i2c_w(struct sd *sd, __u8 reg, __u8 value)
{
int ret = -1;
if (sd->sensor_reg_cache[reg] == value)
return 0;
switch (sd->bridge) {
case BRIDGE_OV511:
case BRIDGE_OV511PLUS:
return ov511_i2c_w(sd, reg, value);
ret = ov511_i2c_w(sd, reg, value);
break;
case BRIDGE_OV518:
case BRIDGE_OV518PLUS:
case BRIDGE_OV519:
return ov518_i2c_w(sd, reg, value);
ret = ov518_i2c_w(sd, reg, value);
break;
case BRIDGE_OVFX2:
return ovfx2_i2c_w(sd, reg, value);
ret = ovfx2_i2c_w(sd, reg, value);
break;
case BRIDGE_W9968CF:
return w9968cf_i2c_w(sd, reg, value);
ret = w9968cf_i2c_w(sd, reg, value);
break;
}
return -1; /* Should never happen */
if (ret >= 0) {
/* Up on sensor reset empty the register cache */
if (reg == 0x12 && (value & 0x80))
memset(sd->sensor_reg_cache, -1,
sizeof(sd->sensor_reg_cache));
else
sd->sensor_reg_cache[reg] = value;
}
return ret;
}
static int i2c_r(struct sd *sd, __u8 reg)
{
int ret;
if (sd->sensor_reg_cache[reg] != -1)
return sd->sensor_reg_cache[reg];
switch (sd->bridge) {
case BRIDGE_OV511:
case BRIDGE_OV511PLUS:
return ov511_i2c_r(sd, reg);
ret = ov511_i2c_r(sd, reg);
break;
case BRIDGE_OV518:
case BRIDGE_OV518PLUS:
case BRIDGE_OV519:
return ov518_i2c_r(sd, reg);
ret = ov518_i2c_r(sd, reg);
break;
case BRIDGE_OVFX2:
return ovfx2_i2c_r(sd, reg);
ret = ovfx2_i2c_r(sd, reg);
break;
case BRIDGE_W9968CF:
return w9968cf_i2c_r(sd, reg);
ret = w9968cf_i2c_r(sd, reg);
break;
}
return -1; /* Should never happen */
if (ret >= 0)
sd->sensor_reg_cache[reg] = ret;
return ret;
}
/* Writes bits at positions specified by mask to an I2C reg. Bits that are in