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Commit 21482415 authored by Jemma Denson's avatar Jemma Denson Committed by Mauro Carvalho Chehab
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media: isl6421: add checks for current overflow 

This Kaffeine's BZ:
	https://bugs.kde.org/show_bug.cgi?id=374693

affects SkyStar S2 PCI DVB-S/S2 rev 3.3 device. It could be due to
a Kernel bug.

While checking the Isil 6421, comparing with its manual, available at:

	http://www.intersil.com/content/dam/Intersil/documents/isl6/isl6421a.pdf



It was noticed that, if the output load is highly capacitive, a different approach
is recomended when energizing the LNBf.

Also, it is possible to detect if a current overload is happening, by checking an
special flag.

Add support for it.

Tested on Skystar S2. Changes respect override_or option so should still work fine
on cx88 based cards which disable dynamic current limit.

Changes since v1:
v2 - fixed incorrect checking of i2c return values
v3 - fix if logic to check if dcl needs re-enabling
   - respect override_or values which aim to disable dcl
   - only do long sleep on overload if dcl enabled
   - add short sleep before re-enabling dcl
   - only check overload and potentially return EINVAL if device is on
v4 - revert v3 sleep logic changes to remove tuning delays

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: default avatarJemma Denson <jdenson@gmail.com>
parent 7112b490

drivers/media/dvb-frontends/isl6421.c

+72 −4
Original line number Diff line number Diff line
@@ -38,35 +38,101 @@ struct isl6421 { 
	u8			override_and;

	struct i2c_adapter	*i2c;

	u8			i2c_addr;

	bool			is_off;

};



static int isl6421_set_voltage(struct dvb_frontend *fe,

			       enum fe_sec_voltage voltage)

{

	int ret;

	u8 buf;

	bool is_off;

	struct isl6421 *isl6421 = (struct isl6421 *) fe->sec_priv;

	struct i2c_msg msg = {	.addr = isl6421->i2c_addr, .flags = 0,

	struct i2c_msg msg[2] = {

		{

		  .addr = isl6421->i2c_addr,

		  .flags = 0,

		  .buf = &isl6421->config,

				.len = sizeof(isl6421->config) };

		  .len = 1,

		}, {

		  .addr = isl6421->i2c_addr,

		  .flags = I2C_M_RD,

		  .buf = &buf,

		  .len = 1,

		}



	};



	isl6421->config &= ~(ISL6421_VSEL1 | ISL6421_EN1);



	switch(voltage) {

	case SEC_VOLTAGE_OFF:

		is_off = true;

		break;

	case SEC_VOLTAGE_13:

		is_off = false;

		isl6421->config |= ISL6421_EN1;

		break;

	case SEC_VOLTAGE_18:

		is_off = false;

		isl6421->config |= (ISL6421_EN1 | ISL6421_VSEL1);

		break;

	default:

		return -EINVAL;

	}



	/*

	 * If LNBf were not powered on, disable dynamic current limit, as,

	 * according with datasheet, highly capacitive load on the output may

	 * cause a difficult start-up.

	 */

	if (isl6421->is_off && !is_off)

		isl6421->config |= ISL6421_DCL;



	isl6421->config |= isl6421->override_or;

	isl6421->config &= isl6421->override_and;



	return (i2c_transfer(isl6421->i2c, &msg, 1) == 1) ? 0 : -EIO;

	ret = i2c_transfer(isl6421->i2c, msg, 2);

	if (ret < 0)

		return ret;

	if (ret != 2)

		return -EIO;



	/* Store off status now incase future commands fail */

	isl6421->is_off = is_off;



	/* On overflow, the device will try again after 900 ms (typically) */

	if (!is_off && (buf & ISL6421_OLF1))

		msleep(1000);



	/* Re-enable dynamic current limit */

	if ((isl6421->config & ISL6421_DCL) &&

	    !(isl6421->override_or & ISL6421_DCL)) {

		isl6421->config &= ~ISL6421_DCL;



		ret = i2c_transfer(isl6421->i2c, msg, 2);

		if (ret < 0)

			return ret;

		if (ret != 2)

			return -EIO;

	}



	/* Check if overload flag is active. If so, disable power */

	if (!is_off && (buf & ISL6421_OLF1)) {

		isl6421->config &= ~(ISL6421_VSEL1 | ISL6421_EN1);

		ret = i2c_transfer(isl6421->i2c, msg, 1);

		if (ret < 0)

			return ret;

		if (ret != 1)

			return -EIO;

		isl6421->is_off = true;



		dev_warn(&isl6421->i2c->dev,

			 "Overload current detected. disabling LNBf power\n");

		return -EINVAL;

	}



	return 0;

}



static int isl6421_enable_high_lnb_voltage(struct dvb_frontend *fe, long arg)
@@ -148,6 +214,8 @@ struct dvb_frontend *isl6421_attach(struct dvb_frontend *fe, struct i2c_adapter 
		return NULL;

	}



	isl6421->is_off = true;



	/* install release callback */

	fe->ops.release_sec = isl6421_release;