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| author | Chris Wilson <chris@chris-wilson.co.uk> | 2011-04-05 16:04:39 +0100 |
|---|---|---|
| committer | Keith Packard <keithp@keithp.com> | 2011-04-05 09:05:34 -0700 |
| commit | 0de009c900e7ebd21097797f723a40813e953879 (patch) | |
| tree | 48a314a677088da01022e7f3ff119353cc55c861 /drivers | |
| parent | 7f58aabc369014fda3a4a33604ba0a1b63b941ac (diff) | |
| download | linux-0de009c900e7ebd21097797f723a40813e953879.tar.bz2 | |
drm/i915/crt: Remove 0xa0 probe for VGA
This is a moral revert of 6ec3d0c0e9c0c605696e91048eebaca7b0c36695.
Following the fix to reset the GMBUS controller after a NAK, we finally
utilize the 0xa0 probe for a CRT connection. And discover that the code
is broken. Shock.
There are a number of issues, but following a key insight from Dave
Airlie, that 0xA0 is an invalid address on a 7-bit bus (though not if we
were to enable 10-bit addressing), and would look like the EDID port
0x50, it is possible to see where the confusion starts.
In short, a write to 0xA0 is accepted by the GMBUS controller which we
interpreted as meaning the existence of a connection (a slave on the
other end of the wire ACKing the write). That was false.
During testing with a broken GMBUS implementation, which never reset an
earlier NAK, this test always reported a NAK and so we proceeded on to
the next test.
Reported-and-tested-by: Sitsofe Wheeler <sitsofe@yahoo.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=35904
Reported-and-tested-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=32612
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Dave Airlie <airlied@linux.ie>
Signed-off-by: Keith Packard <keithp@keithp.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_crt.c | 20 |
1 files changed, 0 insertions, 20 deletions
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c index 8342259f3160..d03fc05b39c0 100644 --- a/drivers/gpu/drm/i915/intel_crt.c +++ b/drivers/gpu/drm/i915/intel_crt.c @@ -269,21 +269,6 @@ static bool intel_crt_detect_hotplug(struct drm_connector *connector) return ret; } -static bool intel_crt_ddc_probe(struct drm_i915_private *dev_priv, int ddc_bus) -{ - u8 buf; - struct i2c_msg msgs[] = { - { - .addr = 0xA0, - .flags = 0, - .len = 1, - .buf = &buf, - }, - }; - /* DDC monitor detect: Does it ACK a write to 0xA0? */ - return i2c_transfer(&dev_priv->gmbus[ddc_bus].adapter, msgs, 1) == 1; -} - static bool intel_crt_detect_ddc(struct drm_connector *connector) { struct intel_crt *crt = intel_attached_crt(connector); @@ -293,11 +278,6 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector) if (crt->base.type != INTEL_OUTPUT_ANALOG) return false; - if (intel_crt_ddc_probe(dev_priv, dev_priv->crt_ddc_pin)) { - DRM_DEBUG_KMS("CRT detected via DDC:0xa0\n"); - return true; - } - if (intel_ddc_probe(&crt->base, dev_priv->crt_ddc_pin)) { struct edid *edid; bool is_digital = false; |