diff options
| author | Daniel Kurtz <djkurtz@chromium.org> | 2012-04-13 19:47:53 +0800 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2012-04-13 15:02:52 +0200 |
| commit | 79985eee842ef146ed6307a29fdc2fa008036421 (patch) | |
| tree | b8b454b646b3ffa35de316728b53e8fd3869d713 /drivers/gpu/drm/i915/intel_i2c.c | |
| parent | f637fde434c9e3687798730c7ddd367e93666013 (diff) | |
drm/i915/intel_i2c: handle zero-length reads
A common method of probing an i2c bus is trying to do a zero-length read.
Handle this case by checking the length first waiting for data to be read.
This is actually important, since attempting a zero-length read is one
of the ways that i2cdetect and i2c_new_probed_device detect whether
there is device present on the bus with a given address.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=48269
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/i915/intel_i2c.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_i2c.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c index cab879fedf3..e2491604255 100644 --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -217,7 +217,7 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg, (len << GMBUS_BYTE_COUNT_SHIFT) | (msg->addr << GMBUS_SLAVE_ADDR_SHIFT) | GMBUS_SLAVE_READ | GMBUS_SW_RDY); - do { + while (len) { int ret; u32 val, loop = 0; u32 gmbus2; @@ -235,7 +235,7 @@ gmbus_xfer_read(struct drm_i915_private *dev_priv, struct i2c_msg *msg, *buf++ = val & 0xff; val >>= 8; } while (--len && ++loop < 4); - } while (len); + } return 0; } |