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From: Jonathan Corbet on 28 Apr 2010 18:30
....otherwise it seems we run into conflicts with shadowy other users which
don't expect to see i2c taking control of ports it never used to do
anything with.

Reported-by: Florian Tobias Schandinat <FlorianSchandinat(a)gmx.de>
Signed-off-by: Jonathan Corbet <corbet(a)lwn.net>
---
drivers/video/via/via_i2c.c | 19 +++++++++++++------
drivers/video/via/via_i2c.h | 1 +
2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/video/via/via_i2c.c b/drivers/video/via/via_i2c.c
index fe5535c..b5253e3 100644
--- a/drivers/video/via/via_i2c.c
+++ b/drivers/video/via/via_i2c.c
@@ -170,13 +170,18 @@ static int create_i2c_bus(struct i2c_adapter *adapter,
return i2c_bit_add_bus(adapter);
}

+/*
+ * By default, we only activate busses on ports 2c and 31 to avoid
+ * conflicts with other possible users; that default can be changed
+ * below.
+ */
static struct via_i2c_adap_cfg adap_configs[] = {
- [VIA_I2C_ADAP_26] = { VIA_I2C_I2C, VIASR, 0x26 },
- [VIA_I2C_ADAP_31] = { VIA_I2C_I2C, VIASR, 0x31 },
- [VIA_I2C_ADAP_25] = { VIA_I2C_GPIO, VIASR, 0x25 },
- [VIA_I2C_ADAP_2C] = { VIA_I2C_GPIO, VIASR, 0x2c },
- [VIA_I2C_ADAP_3D] = { VIA_I2C_GPIO, VIASR, 0x3d },
- { 0, 0, 0 }
+ [VIA_I2C_ADAP_26] = { VIA_I2C_I2C, VIASR, 0x26, 0 },
+ [VIA_I2C_ADAP_31] = { VIA_I2C_I2C, VIASR, 0x31, 1 },
+ [VIA_I2C_ADAP_25] = { VIA_I2C_GPIO, VIASR, 0x25, 0 },
+ [VIA_I2C_ADAP_2C] = { VIA_I2C_GPIO, VIASR, 0x2c, 1 },
+ [VIA_I2C_ADAP_3D] = { VIA_I2C_GPIO, VIASR, 0x3d, 0 },
+ { 0, 0, 0, 0 }
};

int viafb_create_i2c_busses(struct viafb_par *viapar)
@@ -189,6 +194,8 @@ int viafb_create_i2c_busses(struct viafb_par *viapar)

if (adap_cfg->type == 0)
break;
+ if (!adap_cfg->is_active)
+ continue;

ret = create_i2c_bus(&i2c_stuff->adapter,
&i2c_stuff->algo, adap_cfg,
diff --git a/drivers/video/via/via_i2c.h b/drivers/video/via/via_i2c.h
index 00ed978..73d682f 100644
--- a/drivers/video/via/via_i2c.h
+++ b/drivers/video/via/via_i2c.h
@@ -35,6 +35,7 @@ struct via_i2c_adap_cfg {
enum via_i2c_type type;
u_int16_t io_port;
u_int8_t ioport_index;
+ u8 is_active;
};

struct via_i2c_stuff {
--
1.7.0.1

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Prev: [PATCH 27/30] viafb: replace inb/outb
Next: [PATCH 18/30] via: Do not attempt I/O on inactive I2C adapters