From f1feda70b5dfdbe6a1069efffec099b430467331 Mon Sep 17 00:00:00 2001
From: Francisco Jerez <currojerez@riseup.net>
Date: Fri, 23 Jul 2010 23:17:57 +0200
Subject: [PATCH] drm/nouveau: Put back the old 2-messages I2C slave test.
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>
---
drivers/gpu/drm/nouveau/nouveau_i2c.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nouveau_i2c.c b/drivers/gpu/drm/nouveau/nouveau_i2c.c
index 97ba89ef42a0..5588e66dd9fc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_i2c.c
+++ b/drivers/gpu/drm/nouveau/nouveau_i2c.c
@@ -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
--
2.20.1