diff options
| author | Daniel Kurtz <djkurtz@chromium.org> | 2012-03-30 19:46:37 +0800 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2012-04-12 21:14:06 +0200 |
| commit | 7a39a9d4767e8d22d60f2c4bf5eece4f4398c274 (patch) | |
| tree | f76f557e76b5aa0bdfaa5c81b3d8e1176786dfb6 /drivers/gpu/drm/i915/intel_i2c.c | |
| parent | 26883c31b0799e76edf8f0ea8be48b64e09b2a7d (diff) | |
drm/i915/intel_i2c: use double-buffered writes
The GMBUS controller GMBUS3 register is double-buffered. Take advantage
of this by writing two 4-byte words before the first wait for HW_RDY.
This helps keep the GMBUS controller from becoming idle during long writes.
In fact, during experiments using the GMBUS interrupts, the HW_RDY
interrupt would only trigger for transactions >4 bytes after 2 writes
to GMBUS3.
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 | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c index 99a04f8bcb1..f02e52aca74 100644 --- a/drivers/gpu/drm/i915/intel_i2c.c +++ b/drivers/gpu/drm/i915/intel_i2c.c @@ -262,13 +262,6 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg, GMBUS_SLAVE_WRITE | GMBUS_SW_RDY); POSTING_READ(GMBUS2 + reg_offset); while (len) { - if (wait_for(I915_READ(GMBUS2 + reg_offset) & - (GMBUS_SATOER | GMBUS_HW_RDY), - 50)) - return -ETIMEDOUT; - if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER) - return -ENXIO; - val = loop = 0; do { val |= *buf++ << (8 * loop); @@ -276,6 +269,13 @@ gmbus_xfer_write(struct drm_i915_private *dev_priv, struct i2c_msg *msg, I915_WRITE(GMBUS3 + reg_offset, val); POSTING_READ(GMBUS2 + reg_offset); + + if (wait_for(I915_READ(GMBUS2 + reg_offset) & + (GMBUS_SATOER | GMBUS_HW_RDY), + 50)) + return -ETIMEDOUT; + if (I915_READ(GMBUS2 + reg_offset) & GMBUS_SATOER) + return -ENXIO; } return 0; } |