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drm/nouveau: Put back the old 2-messages I2C slave test.

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I was hoping we could detect I2C devices at a given address without
actually writing data into them, but apparently some DDC slaves get
confused with 0-bytes transactions. Put the good old test back.

Reported-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
This commit is contained in:
Francisco Jerez 2010-07-23 23:17:57 +02:00 committed by Ben Skeggs
parent e04d8e829d
commit f1feda70b5
1 changed files with 15 additions and 4 deletions
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19
drivers/gpu/drm/nouveau/nouveau_i2c.c
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@ -281,12 +281,23 @@ nouveau_i2c_find(struct drm_device *dev, int index)
bool
nouveau_probe_i2c_addr(struct nouveau_i2c_chan *i2c, int addr)
{
struct i2c_msg msg = {
.addr = addr,
.len = 0,
uint8_t buf[] = { 0 };
struct i2c_msg msgs[] = {
{
.addr = addr,
.flags = 0,
.len = 1,
.buf = buf,
},
{
.addr = addr,
.flags = I2C_M_RD,
.len = 1,
.buf = buf,
}
};
return i2c_transfer(&i2c->adapter, &msg, 1) == 1;
return i2c_transfer(&i2c->adapter, msgs, 2) == 2;
}
int