From f1feda70b5dfdbe6a1069efffec099b430467331 Mon Sep 17 00:00:00 2001 From: Francisco Jerez 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 Signed-off-by: Francisco Jerez Signed-off-by: Ben Skeggs --- 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 97ba89ef42a..5588e66dd9f 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 -- 2.39.3