From: Chris Wilson <chris@chris-wilson.co.uk>
To: intel-gfx@lists.freedesktop.org
Subject: [PATCH 3/5] drm/i915/crt: Remove 0xa0 probe for VGA
Date: Tue, 5 Apr 2011 10:24:16 +0100 [thread overview]
Message-ID: <1301995458-2699-4-git-send-email-chris@chris-wilson.co.uk> (raw)
In-Reply-To: <1301995458-2699-1-git-send-email-chris@chris-wilson.co.uk>
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 it 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>
---
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 49ce713..e17bc6b 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;
--
1.7.4.1
next prev parent reply other threads:[~2011-04-05 9:24 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-05 9:24 i915 fixes for review Chris Wilson
2011-04-05 9:24 ` [PATCH 1/5] drm/i915: Initialise g4x watermarks for disabled pipes Chris Wilson
2011-04-05 20:56 ` Keith Packard
2011-04-05 21:12 ` Chris Wilson
2011-04-06 1:02 ` Keith Packard
2011-04-06 6:59 ` Chris Wilson
2011-04-06 7:36 ` Keith Packard
2011-04-06 8:02 ` Chris Wilson
2011-04-06 15:12 ` Keith Packard
2011-04-05 9:24 ` [PATCH 2/5] drm/i915/crt: Explicitly return false if connected to a digital monitor Chris Wilson
2011-04-05 20:57 ` Keith Packard
2011-04-05 9:24 ` Chris Wilson [this message]
2011-04-05 9:24 ` [PATCH 4/5] drm/i915/lvds: Remove 0xA0 DDC probe for LVDS Chris Wilson
2011-04-05 9:24 ` [PATCH 5/5] drm/i915/gmbus: Reset the controller on initialisation Chris Wilson
2011-04-05 16:18 ` Ben Widawsky
2011-04-05 16:27 ` Ben Widawsky
2011-04-05 20:59 ` Keith Packard
2011-04-05 21:26 ` Chris Wilson
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