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| author | Daniel Kurtz <djkurtz@chromium.org> | 2012-03-30 19:46:36 +0800 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2012-04-12 21:14:06 +0200 |
| commit | 26883c31b0799e76edf8f0ea8be48b64e09b2a7d (patch) | |
| tree | a8ff83254d592500a16ed7843e103eb87316299d /drivers/gpu/drm/i915/intel_i2c.c | |
| parent | 3fdcf43192559f53305644d0c1e0f7dda398f091 (diff) | |
| download | olio-linux-3.10-26883c31b0799e76edf8f0ea8be48b64e09b2a7d.tar.xz olio-linux-3.10-26883c31b0799e76edf8f0ea8be48b64e09b2a7d.zip | |
drm/i915/intel_i2c: handle zero-length writes
A common method of probing an i2c bus is trying to do a zero-length write.
Handle this case by checking the length first before decrementing it.
This is actually important, since attempting a zero-length write 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.
Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
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 | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c index c12db726589..99a04f8bcb1 100644 --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -248,9 +248,10 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg, u32 val, loop; val = loop = 0; - do { - val |= *buf++ << (8 * loop); - } while (--len && ++loop < 4); + while (len && loop < 4) { + val |= *buf++ << (8 * loop++); + len -= 1; + } I915_WRITE(GMBUS3 + reg_offset, val); I915_WRITE(GMBUS1 + reg_offset, |