From b66d842467311ac3434aa19c5c41deaab8295bd0 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 12 Aug 2010 15:26:41 +0100 Subject: [PATCH] drm/i915/sdvo: Restore guess of 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 Bug 15109 - i945GM fails to detect EDID on DVI port https://bugzilla.kernel.org/show_bug.cgi?id=15109 Signed-off-by: Chris Wilson Reported-and-tested-by: Paul Neumann Cc: Adam Jackson Cc: Zhenyu Wang Cc: stable@kernel.org --- drivers/gpu/drm/i915/intel_sdvo.c | 40 ++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c index 62d22ae4a1d1..e3b7a7ee39cb 100644 --- a/drivers/gpu/drm/i915/intel_sdvo.c +++ b/drivers/gpu/drm/i915/intel_sdvo.c @@ -1929,6 +1929,41 @@ 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 @@ -1948,7 +1983,10 @@ 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 -- 2.20.1