[media] DiBxxxx: get rid of DMA buffer on stack

This patch removes the remaining on-stack buffer for USB DMA transfer.
This patch also reduces the stack memory usage.

Cc: stable@kernel.org
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: Olivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: Patrick Boettcher <patrick.boettcher@dibcom.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/dib0070.c

@@ -73,27 +73,47 @@ struct dib0070_state {
 
     u8  wbd_gain_current;
 	u16 wbd_offset_3_3[2];
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[3];
+	u8 i2c_read_buffer[2];
 };
 
 static uint16_t dib0070_read_reg(struct dib0070_state *state, u8 reg)
 {
-	u8 b[2];
-	struct i2c_msg msg[2] = {
-		{ .addr = state->cfg->i2c_address, .flags = 0,        .buf = &reg, .len = 1 },
-		{ .addr = state->cfg->i2c_address, .flags = I2C_M_RD, .buf = b,  .len = 2 },
-	};
-	if (i2c_transfer(state->i2c, msg, 2) != 2) {
+	state->i2c_write_buffer[0] = reg;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->cfg->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 1;
+	state->msg[1].addr = state->cfg->i2c_address;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c, state->msg, 2) != 2) {
 		printk(KERN_WARNING "DiB0070 I2C read failed\n");
 		return 0;
 	}
-	return (b[0] << 8) | b[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib0070_write_reg(struct dib0070_state *state, u8 reg, u16 val)
 {
-	u8 b[3] = { reg, val >> 8, val & 0xff };
-	struct i2c_msg msg = { .addr = state->cfg->i2c_address, .flags = 0, .buf = b, .len = 3 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = reg;
+	state->i2c_write_buffer[1] = val >> 8;
+	state->i2c_write_buffer[2] = val & 0xff;
+
+	memset(state->msg, 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->cfg->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 3;
+
+	if (i2c_transfer(state->i2c, state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0070 I2C write failed\n");
 		return -EREMOTEIO;
 	}

drivers/media/dvb/frontends/dib0090.c

@@ -191,6 +191,11 @@ struct dib0090_state {
 	u8 wbd_calibration_gain;
 	const struct dib0090_wbd_slope *current_wbd_table;
 	u16 wbdmux;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[3];
+	u8 i2c_read_buffer[2];
 };
 
 struct dib0090_fw_state {
@@ -198,27 +203,48 @@ struct dib0090_fw_state {
 	struct dvb_frontend *fe;
 	struct dib0090_identity identity;
 	const struct dib0090_config *config;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg;
+	u8 i2c_write_buffer[2];
+	u8 i2c_read_buffer[2];
 };
 
 static u16 dib0090_read_reg(struct dib0090_state *state, u8 reg)
 {
-	u8 b[2];
-	struct i2c_msg msg[2] = {
-		{.addr = state->config->i2c_address, .flags = 0, .buf = &reg, .len = 1},
-		{.addr = state->config->i2c_address, .flags = I2C_M_RD, .buf = b, .len = 2},
-	};
-	if (i2c_transfer(state->i2c, msg, 2) != 2) {
+	state->i2c_write_buffer[0] = reg;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->config->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 1;
+	state->msg[1].addr = state->config->i2c_address;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c, state->msg, 2) != 2) {
 		printk(KERN_WARNING "DiB0090 I2C read failed\n");
 		return 0;
 	}
-	return (b[0] << 8) | b[1];
+
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib0090_write_reg(struct dib0090_state *state, u32 reg, u16 val)
 {
-	u8 b[3] = { reg & 0xff, val >> 8, val & 0xff };
-	struct i2c_msg msg = {.addr = state->config->i2c_address, .flags = 0, .buf = b, .len = 3 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = reg & 0xff;
+	state->i2c_write_buffer[1] = val >> 8;
+	state->i2c_write_buffer[2] = val & 0xff;
+
+	memset(state->msg, 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->config->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 3;
+
+	if (i2c_transfer(state->i2c, state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C write failed\n");
 		return -EREMOTEIO;
 	}
@@ -227,20 +253,31 @@ static int dib0090_write_reg(struct dib0090_state *state, u32 reg, u16 val)
 
 static u16 dib0090_fw_read_reg(struct dib0090_fw_state *state, u8 reg)
 {
-	u8 b[2];
-	struct i2c_msg msg = {.addr = reg, .flags = I2C_M_RD, .buf = b, .len = 2 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = reg;
+
+	memset(&state->msg, 0, sizeof(struct i2c_msg));
+	state->msg.addr = reg;
+	state->msg.flags = I2C_M_RD;
+	state->msg.buf = state->i2c_read_buffer;
+	state->msg.len = 2;
+	if (i2c_transfer(state->i2c, &state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C read failed\n");
 		return 0;
 	}
-	return (b[0] << 8) | b[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib0090_fw_write_reg(struct dib0090_fw_state *state, u8 reg, u16 val)
 {
-	u8 b[2] = { val >> 8, val & 0xff };
-	struct i2c_msg msg = {.addr = reg, .flags = 0, .buf = b, .len = 2 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = val >> 8;
+	state->i2c_write_buffer[1] = val & 0xff;
+
+	memset(&state->msg, 0, sizeof(struct i2c_msg));
+	state->msg.addr = reg;
+	state->msg.flags = 0;
+	state->msg.buf = state->i2c_write_buffer;
+	state->msg.len = 2;
+	if (i2c_transfer(state->i2c, &state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C write failed\n");
 		return -EREMOTEIO;
 	}

drivers/media/dvb/frontends/dib7000m.c

@@ -50,6 +50,11 @@ struct dib7000m_state {
 	u16 revision;
 
 	u8 agc_state;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[4];
+	u8 i2c_read_buffer[2];
 };
 
 enum dib7000m_power_mode {
@@ -64,29 +69,39 @@ enum dib7000m_power_mode {
 
 static u16 dib7000m_read_word(struct dib7000m_state *state, u16 reg)
 {
-	u8 wb[2] = { (reg >> 8) | 0x80, reg & 0xff };
-	u8 rb[2];
-	struct i2c_msg msg[2] = {
-		{ .addr = state->i2c_addr >> 1, .flags = 0,        .buf = wb, .len = 2 },
-		{ .addr = state->i2c_addr >> 1, .flags = I2C_M_RD, .buf = rb, .len = 2 },
-	};
-
-	if (i2c_transfer(state->i2c_adap, msg, 2) != 2)
+	state->i2c_write_buffer[0] = (reg >> 8) | 0x80;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c_addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c_adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d",reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib7000m_write_word(struct dib7000m_state *state, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = state->i2c_addr >> 1, .flags = 0, .buf = b, .len = 4
-	};
-	return i2c_transfer(state->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = reg & 0xff;
+	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	state->i2c_write_buffer[3] = val & 0xff;
+
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 4;
+
+	return i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 static void dib7000m_write_tab(struct dib7000m_state *state, u16 *buf)
 {

drivers/media/dvb/frontends/dib7000p.c

@@ -63,6 +63,11 @@ struct dib7000p_state {
 
 	u16 tuner_enable;
 	struct i2c_adapter dib7090_tuner_adap;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[4];
+	u8 i2c_read_buffer[2];
 };
 
 enum dib7000p_power_mode {
@@ -76,29 +81,39 @@ static int dib7090_set_diversity_in(struct dvb_frontend *fe, int onoff);
 
 static u16 dib7000p_read_word(struct dib7000p_state *state, u16 reg)
 {
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	u8 rb[2];
-	struct i2c_msg msg[2] = {
-		{.addr = state->i2c_addr >> 1, .flags = 0, .buf = wb, .len = 2},
-		{.addr = state->i2c_addr >> 1, .flags = I2C_M_RD, .buf = rb, .len = 2},
-	};
+	state->i2c_write_buffer[0] = reg >> 8;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c_addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
 
-	if (i2c_transfer(state->i2c_adap, msg, 2) != 2)
+	if (i2c_transfer(state->i2c_adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib7000p_write_word(struct dib7000p_state *state, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = state->i2c_addr >> 1, .flags = 0, .buf = b, .len = 4
-	};
-	return i2c_transfer(state->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = reg & 0xff;
+	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	state->i2c_write_buffer[3] = val & 0xff;
+
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 4;
+
+	return i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
 static void dib7000p_write_tab(struct dib7000p_state *state, u16 * buf)
@@ -1550,11 +1565,24 @@ static void dib7000p_release(struct dvb_frontend *demod)
 
 int dib7000pc_detection(struct i2c_adapter *i2c_adap)
 {
-	u8 tx[2], rx[2];
+	u8 *tx, *rx;
 	struct i2c_msg msg[2] = {
-		{.addr = 18 >> 1, .flags = 0, .buf = tx, .len = 2},
-		{.addr = 18 >> 1, .flags = I2C_M_RD, .buf = rx, .len = 2},
+		{.addr = 18 >> 1, .flags = 0, .len = 2},
+		{.addr = 18 >> 1, .flags = I2C_M_RD, .len = 2},
 	};
+	int ret = 0;
+
+	tx = kzalloc(2*sizeof(u8), GFP_KERNEL);
+	if (!tx)
+		return -ENOMEM;
+	rx = kzalloc(2*sizeof(u8), GFP_KERNEL);
+	if (!rx) {
+		goto rx_memory_error;
+		ret = -ENOMEM;
+	}
+
+	msg[0].buf = tx;
+	msg[1].buf = rx;
 
 	tx[0] = 0x03;
 	tx[1] = 0x00;
@@ -1574,7 +1602,11 @@ int dib7000pc_detection(struct i2c_adapter *i2c_adap)
 		}
 
 	dprintk("-D-  DiB7000PC not detected");
-	return 0;
+
+	kfree(rx);
+rx_memory_error:
+	kfree(tx);
+	return ret;
 }
 EXPORT_SYMBOL(dib7000pc_detection);
 

drivers/media/dvb/frontends/dib8000.c

@@ -35,6 +35,8 @@ MODULE_PARM_DESC(debug, "turn on debugging (default: 0)");
 struct i2c_device {
 	struct i2c_adapter *adap;
 	u8 addr;
+	u8 *i2c_write_buffer;
+	u8 *i2c_read_buffer;
 };
 
 struct dib8000_state {
@@ -70,6 +72,11 @@ struct dib8000_state {
 	u32 status;
 
 	struct dvb_frontend *fe[MAX_NUMBER_OF_FRONTENDS];
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[4];
+	u8 i2c_read_buffer[2];
 };
 
 enum dib8000_power_mode {
@@ -79,22 +86,41 @@ enum dib8000_power_mode {
 
 static u16 dib8000_i2c_read16(struct i2c_device *i2c, u16 reg)
 {
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	u8 rb[2];
 	struct i2c_msg msg[2] = {
-		{.addr = i2c->addr >> 1,.flags = 0,.buf = wb,.len = 2},
-		{.addr = i2c->addr >> 1,.flags = I2C_M_RD,.buf = rb,.len = 2},
+		{.addr = i2c->addr >> 1, .flags = 0,
+			.buf = i2c->i2c_write_buffer, .len = 2},
+		{.addr = i2c->addr >> 1, .flags = I2C_M_RD,
+			.buf = i2c->i2c_read_buffer, .len = 2},
 	};
 
+	msg[0].buf[0] = reg >> 8;
+	msg[0].buf[1] = reg & 0xff;
+
 	if (i2c_transfer(i2c->adap, msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (msg[1].buf[0] << 8) | msg[1].buf[1];
 }
 
 static u16 dib8000_read_word(struct dib8000_state *state, u16 reg)
 {
-	return dib8000_i2c_read16(&state->i2c, reg);
+	state->i2c_write_buffer[0] = reg >> 8;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c.addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c.addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c.adap, state->msg, 2) != 2)
+		dprintk("i2c read error on %d", reg);
+
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static u32 dib8000_read32(struct dib8000_state *state, u16 reg)
@@ -109,19 +135,34 @@ static u32 dib8000_read32(struct dib8000_state *state, u16 reg)
 
 static int dib8000_i2c_write16(struct i2c_device *i2c, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = i2c->addr >> 1,.flags = 0,.buf = b,.len = 4
-	};
-	return i2c_transfer(i2c->adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	struct i2c_msg msg = {.addr = i2c->addr >> 1, .flags = 0,
+		.buf = i2c->i2c_write_buffer, .len = 4};
+	int ret = 0;
+
+	msg.buf[0] = (reg >> 8) & 0xff;
+	msg.buf[1] = reg & 0xff;
+	msg.buf[2] = (val >> 8) & 0xff;
+	msg.buf[3] = val & 0xff;
+
+	ret = i2c_transfer(i2c->adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+
+	return ret;
 }
 
 static int dib8000_write_word(struct dib8000_state *state, u16 reg, u16 val)
 {
-	return dib8000_i2c_write16(&state->i2c, reg, val);
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = reg & 0xff;
+	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	state->i2c_write_buffer[3] = val & 0xff;
+
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c.addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 4;
+
+	return i2c_transfer(state->i2c.adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
 static const s16 coeff_2k_sb_1seg_dqpsk[8] = {
@@ -980,18 +1021,7 @@ static void dib8000_update_timf(struct dib8000_state *state)
 	dprintk("Updated timing frequency: %d (default: %d)", state->timf, state->timf_default);
 }
 
-static void dib8000_set_channel(struct dib8000_state *state, u8 seq, u8 autosearching)
-{
-	u16 mode, max_constellation, seg_diff_mask = 0, nbseg_diff = 0;
-	u8 guard, crate, constellation, timeI;
-	u8 permu_seg[] = { 6, 5, 7, 4, 8, 3, 9, 2, 10, 1, 11, 0, 12 };
-	u16 i, coeff[4], P_cfr_left_edge = 0, P_cfr_right_edge = 0, seg_mask13 = 0x1fff;	// All 13 segments enabled
-	const s16 *ncoeff = NULL, *ana_fe;
-	u16 tmcc_pow = 0;
-	u16 coff_pow = 0x2800;
-	u16 init_prbs = 0xfff;
-	u16 ana_gain = 0;
-	u16 adc_target_16dB[11] = {
+static const u16 adc_target_16dB[11] = {
 	(1 << 13) - 825 - 117,
 	(1 << 13) - 837 - 117,
 	(1 << 13) - 811 - 117,
@@ -1003,7 +1033,19 @@ static void dib8000_set_channel(struct dib8000_state *state, u8 seq, u8 autosear
 	(1 << 13) - 575 - 117,
 	(1 << 13) - 531 - 117,
 	(1 << 13) - 501 - 117
-	};
+};
+static const u8 permu_seg[] = { 6, 5, 7, 4, 8, 3, 9, 2, 10, 1, 11, 0, 12 };
+
+static void dib8000_set_channel(struct dib8000_state *state, u8 seq, u8 autosearching)
+{
+	u16 mode, max_constellation, seg_diff_mask = 0, nbseg_diff = 0;
+	u8 guard, crate, constellation, timeI;
+	u16 i, coeff[4], P_cfr_left_edge = 0, P_cfr_right_edge = 0, seg_mask13 = 0x1fff;	// All 13 segments enabled
+	const s16 *ncoeff = NULL, *ana_fe;
+	u16 tmcc_pow = 0;
+	u16 coff_pow = 0x2800;
+	u16 init_prbs = 0xfff;
+	u16 ana_gain = 0;
 
 	if (state->ber_monitored_layer != LAYER_ALL)
 		dib8000_write_word(state, 285, (dib8000_read_word(state, 285) & 0x60) | state->ber_monitored_layer);
@@ -2379,10 +2421,22 @@ EXPORT_SYMBOL(dib8000_get_slave_frontend);
 
 int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 default_addr, u8 first_addr)
 {
-	int k = 0;
+	int k = 0, ret = 0;
 	u8 new_addr = 0;
 	struct i2c_device client = {.adap = host };
 
+	client.i2c_write_buffer = kzalloc(4 * sizeof(u8), GFP_KERNEL);
+	if (!client.i2c_write_buffer) {
+		dprintk("%s: not enough memory", __func__);
+		return -ENOMEM;
+	}
+	client.i2c_read_buffer = kzalloc(4 * sizeof(u8), GFP_KERNEL);
+	if (!client.i2c_read_buffer) {
+		dprintk("%s: not enough memory", __func__);
+		ret = -ENOMEM;
+		goto error_memory;
+	}
+
 	for (k = no_of_demods - 1; k >= 0; k--) {
 		/* designated i2c address */
 		new_addr = first_addr + (k << 1);
@@ -2394,7 +2448,8 @@ int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 defau
 			client.addr = default_addr;
 			if (dib8000_identify(&client) == 0) {
 				dprintk("#%d: not identified", k);
-				return -EINVAL;
+				ret  = -EINVAL;
+				goto error;
 			}
 		}
 
@@ -2420,7 +2475,12 @@ int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 defau
 		dib8000_i2c_write16(&client, 1286, 0);
 	}
 
-	return 0;
+error:
+	kfree(client.i2c_read_buffer);
+error_memory:
+	kfree(client.i2c_write_buffer);
+
+	return ret;
 }
 
 EXPORT_SYMBOL(dib8000_i2c_enumeration);
@@ -2519,6 +2579,8 @@ struct dvb_frontend *dib8000_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr, s
 	memcpy(&state->cfg, cfg, sizeof(struct dib8000_config));
 	state->i2c.adap = i2c_adap;
 	state->i2c.addr = i2c_addr;
+	state->i2c.i2c_write_buffer = state->i2c_write_buffer;
+	state->i2c.i2c_read_buffer = state->i2c_read_buffer;
 	state->gpio_val = cfg->gpio_val;
 	state->gpio_dir = cfg->gpio_dir;
 

drivers/media/dvb/frontends/dibx000_common.c

@@ -10,30 +10,39 @@ MODULE_PARM_DESC(debug, "turn on debugging (default: 0)");
 
 static int dibx000_write_word(struct dibx000_i2c_master *mst, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = mst->i2c_addr,.flags = 0,.buf = b,.len = 4
-	};
-
-	return i2c_transfer(mst->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	mst->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	mst->i2c_write_buffer[1] = reg & 0xff;
+	mst->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	mst->i2c_write_buffer[3] = val & 0xff;
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg));
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].flags = 0;
+	mst->msg[0].buf = mst->i2c_write_buffer;
+	mst->msg[0].len = 4;
+
+	return i2c_transfer(mst->i2c_adap, mst->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
 static u16 dibx000_read_word(struct dibx000_i2c_master *mst, u16 reg)
 {
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	u8 rb[2];
-	struct i2c_msg msg[2] = {
-		{.addr = mst->i2c_addr, .flags = 0, .buf = wb, .len = 2},
-		{.addr = mst->i2c_addr, .flags = I2C_M_RD, .buf = rb, .len = 2},
-	};
-
-	if (i2c_transfer(mst->i2c_adap, msg, 2) != 2)
+	mst->i2c_write_buffer[0] = reg >> 8;
+	mst->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(mst->msg, 0, 2 * sizeof(struct i2c_msg));
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].flags = 0;
+	mst->msg[0].buf = mst->i2c_write_buffer;
+	mst->msg[0].len = 2;
+	mst->msg[1].addr = mst->i2c_addr;
+	mst->msg[1].flags = I2C_M_RD;
+	mst->msg[1].buf = mst->i2c_read_buffer;
+	mst->msg[1].len = 2;
+
+	if (i2c_transfer(mst->i2c_adap, mst->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (mst->i2c_read_buffer[0] << 8) | mst->i2c_read_buffer[1];
 }
 
 static int dibx000_is_i2c_done(struct dibx000_i2c_master *mst)
@@ -248,26 +257,32 @@ static int dibx000_i2c_gated_gpio67_xfer(struct i2c_adapter *i2c_adap,
 					struct i2c_msg msg[], int num)
 {
 	struct dibx000_i2c_master *mst = i2c_get_adapdata(i2c_adap);
-	struct i2c_msg m[2 + num];
-	u8 tx_open[4], tx_close[4];
 
-	memset(m, 0, sizeof(struct i2c_msg) * (2 + num));
+	if (num > 32) {
+		dprintk("%s: too much I2C message to be transmitted (%i).\
+				Maximum is 32", __func__, num);
+		return -ENOMEM;
+	}
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
 
 	dibx000_i2c_select_interface(mst, DIBX000_I2C_INTERFACE_GPIO_6_7);
 
-	dibx000_i2c_gate_ctrl(mst, tx_open, msg[0].addr, 1);
-	m[0].addr = mst->i2c_addr;
-	m[0].buf = tx_open;
-	m[0].len = 4;
+	/* open the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[0], msg[0].addr, 1);
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].buf = &mst->i2c_write_buffer[0];
+	mst->msg[0].len = 4;
 
-	memcpy(&m[1], msg, sizeof(struct i2c_msg) * num);
+	memcpy(&mst->msg[1], msg, sizeof(struct i2c_msg) * num);
 
-	dibx000_i2c_gate_ctrl(mst, tx_close, 0, 0);
-	m[num + 1].addr = mst->i2c_addr;
-	m[num + 1].buf = tx_close;
-	m[num + 1].len = 4;
+	/* close the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[4], 0, 0);
+	mst->msg[num + 1].addr = mst->i2c_addr;
+	mst->msg[num + 1].buf = &mst->i2c_write_buffer[4];
+	mst->msg[num + 1].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, m, 2 + num) == 2 + num ? num : -EIO;
+	return i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ? num : -EIO;
 }
 
 static struct i2c_algorithm dibx000_i2c_gated_gpio67_algo = {
@@ -279,26 +294,32 @@ static int dibx000_i2c_gated_tuner_xfer(struct i2c_adapter *i2c_adap,
 					struct i2c_msg msg[], int num)
 {
 	struct dibx000_i2c_master *mst = i2c_get_adapdata(i2c_adap);
-	struct i2c_msg m[2 + num];
-	u8 tx_open[4], tx_close[4];
 
-	memset(m, 0, sizeof(struct i2c_msg) * (2 + num));
+	if (num > 32) {
+		dprintk("%s: too much I2C message to be transmitted (%i).\
+				Maximum is 32", __func__, num);
+		return -ENOMEM;
+	}
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
 
 	dibx000_i2c_select_interface(mst, DIBX000_I2C_INTERFACE_TUNER);
 
-	dibx000_i2c_gate_ctrl(mst, tx_open, msg[0].addr, 1);
-	m[0].addr = mst->i2c_addr;
-	m[0].buf = tx_open;
-	m[0].len = 4;
+	/* open the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[0], msg[0].addr, 1);
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].buf = &mst->i2c_write_buffer[0];
+	mst->msg[0].len = 4;
 
-	memcpy(&m[1], msg, sizeof(struct i2c_msg) * num);
+	memcpy(&mst->msg[1], msg, sizeof(struct i2c_msg) * num);
 
-	dibx000_i2c_gate_ctrl(mst, tx_close, 0, 0);
-	m[num + 1].addr = mst->i2c_addr;
-	m[num + 1].buf = tx_close;
-	m[num + 1].len = 4;
+	/* close the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[4], 0, 0);
+	mst->msg[num + 1].addr = mst->i2c_addr;
+	mst->msg[num + 1].buf = &mst->i2c_write_buffer[4];
+	mst->msg[num + 1].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, m, 2 + num) == 2 + num ? num : -EIO;
+	return i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ? num : -EIO;
 }
 
 static struct i2c_algorithm dibx000_i2c_gated_tuner_algo = {

drivers/media/dvb/frontends/dibx000_common.h

@@ -28,6 +28,11 @@ struct dibx000_i2c_master {
 	u8 i2c_addr;
 
 	u16 base_reg;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[34];
+	u8 i2c_write_buffer[8];
+	u8 i2c_read_buffer[2];
 };
 
 extern int dibx000_init_i2c_master(struct dibx000_i2c_master *mst,