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drm/i915: use GMBUS to manage i2c links

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Use the GMBUS interface rather than direct bit banging to grab the EDID
over DDC (and for other forms of auxiliary communication with external
display controllers). The hope is that this method will be much faster
and more reliable than bit banging for fetching EDIDs from buggy monitors
or through switches, though we still preserve the bit banging as a
fallback in case GMBUS fails.

Based on an original patch by Jesse Barnes.

Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Chris Wilson
2010-07-20 15:44:45 -07:00
parent 373a3cf744
commit f899fc64cd
21 changed files with 444 additions and 422 deletions
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16
drivers/gpu/drm/i915/intel_bios.c
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@@ -291,14 +291,6 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
struct bdb_header *bdb)
{
struct bdb_general_definitions *general;
const int crt_bus_map_table[] = {
GPIOB,
GPIOA,
GPIOC,
GPIOD,
GPIOE,
GPIOF,
};
general = find_section(bdb, BDB_GENERAL_DEFINITIONS);
if (general) {
@@ -306,10 +298,8 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
if (block_size >= sizeof(*general)) {
int bus_pin = general->crt_ddc_gmbus_pin;
DRM_DEBUG_KMS("crt_ddc_bus_pin: %d\n", bus_pin);
if ((bus_pin >= 1) && (bus_pin <= 6)) {
dev_priv->crt_ddc_bus =
crt_bus_map_table[bus_pin-1];
}
if (bus_pin >= 1 && bus_pin <= 6)
dev_priv->crt_ddc_pin = bus_pin - 1;
} else {
DRM_DEBUG_KMS("BDB_GD too small (%d). Invalid.\n",
block_size);
@@ -533,6 +523,8 @@ intel_init_bios(struct drm_device *dev)
struct bdb_header *bdb = NULL;
u8 __iomem *bios = NULL;
dev_priv->crt_ddc_pin = GMBUS_PORT_VGADDC;
/* XXX Should this validation be moved to intel_opregion.c? */
if (dev_priv->opregion.vbt) {
struct vbt_header *vbt = dev_priv->opregion.vbt;