Attachment 37815 Details for Bug 29499 – Fallback to guessing the DDC bus without VBIOS.

[patch] Fallback to guessing the DDC bus without VBIOS.

0001-drm-i915-sdvo-Guess-the-DDC-bus-in-absence-of-VBIOS.patch (text/plain), 2.60 KB, created by Chris Wilson on 2010-08-12 07:33:32 UTC

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Creator: Chris Wilson

Created: 2010-08-12 07:33:32 UTC

Size: 2.60 KB

patch

obsolete

>From 9c9f86fc053814477964883da8f7bf9ffd973ff5 Mon Sep 17 00:00:00 2001
>From: Chris Wilson <chris@chris-wilson.co.uk>
>Date: Thu, 12 Aug 2010 15:26:41 +0100
>Subject: [PATCH] drm/i915/sdvo: Guess the DDC bus in absence of VBIOS
>
>If the VBIOS tells us the mapping of the SDVO device onto the DDC bus,
>use it. However, if there is no VBIOS available that mapping is
>uninitialised and we should fallback to our earlier guess.
>
>Fix regression introduced in b1083333 (which in turn is a fix for the
>regression caused by the introduction of this guess, 14571b4).
>
>References:
>
>  Bug 29499 - [945GM] Screen disconnected because of missing VBIOS
>  https://bugs.freedesktop.org/show_bug.cgi?id=29499
>
>Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>Reported-by: Paul Neumann <paul104x@yahoo.de>
>Cc: Adam Jackson <ajax@redhat.com>
>Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
>---
> drivers/gpu/drm/i915/intel_sdvo.c |   40 ++++++++++++++++++++++++++++++++++++-
> 1 files changed, 39 insertions(+), 1 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
>index 2708631..e4132e5 100644
>--- a/drivers/gpu/drm/i915/intel_sdvo.c
>+++ b/drivers/gpu/drm/i915/intel_sdvo.c
>@@ -1936,6 +1936,41 @@ static const struct drm_encoder_funcs intel_sdvo_enc_funcs = {
> 	.destroy = intel_sdvo_enc_destroy,
> };
> 
>+static void
>+intel_sdvo_guess_ddc_bus(struct intel_sdvo *sdvo)
>+{
>+	uint16_t mask = 0;
>+	unsigned int num_bits;
>+
>+	/* Make a mask of outputs less than or equal to our own priority in the
>+	 * list.
>+	 */
>+	switch (sdvo->controlled_output) {
>+	case SDVO_OUTPUT_LVDS1:
>+		mask |= SDVO_OUTPUT_LVDS1;
>+	case SDVO_OUTPUT_LVDS0:
>+		mask |= SDVO_OUTPUT_LVDS0;
>+	case SDVO_OUTPUT_TMDS1:
>+		mask |= SDVO_OUTPUT_TMDS1;
>+	case SDVO_OUTPUT_TMDS0:
>+		mask |= SDVO_OUTPUT_TMDS0;
>+	case SDVO_OUTPUT_RGB1:
>+		mask |= SDVO_OUTPUT_RGB1;
>+	case SDVO_OUTPUT_RGB0:
>+		mask |= SDVO_OUTPUT_RGB0;
>+		break;
>+	}
>+
>+	/* Count bits to find what number we are in the priority list. */
>+	mask &= sdvo->caps.output_flags;
>+	num_bits = hweight16(mask);
>+	/* If more than 3 outputs, default to DDC bus 3 for now. */
>+	if (num_bits > 3)
>+		num_bits = 3;
>+
>+	/* Corresponds to SDVO_CONTROL_BUS_DDCx */
>+	sdvo->ddc_bus = 1 << num_bits;
>+}
> 
> /**
>  * Choose the appropriate DDC bus for control bus switch command for this
>@@ -1955,7 +1990,10 @@ intel_sdvo_select_ddc_bus(struct drm_i915_private *dev_priv,
> 	else
> 		mapping = &(dev_priv->sdvo_mappings[1]);
> 
>-	sdvo->ddc_bus = 1 << ((mapping->ddc_pin & 0xf0) >> 4);
>+	if (mapping->initialized)
>+		sdvo->ddc_bus = 1 << ((mapping->ddc_pin & 0xf0) >> 4);
>+	else
>+		intel_sdvo_guess_ddc_bus(sdvo);
> }
> 
> static bool
>-- 
>1.7.1
>

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Attachments on bug 29499: 37784 | 37788 | 37815

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