Commit 1a1841d3 authored by Ben Skeggs's avatar Ben Skeggs
Browse files

drm/nouveau: do not forcibly power on lvds panels

This fix was put in place to fix a bug where the eDP panel on certain
laptops fails to respond over the aux channel after suspend.

It appears that on some systems (Dell M6600, with LVDS panel) there's a
very bad interaction with the eDP init table that causes the SOR to get
very confused and not drive the panel correctly, leading to bleed.

A DPMS off/on cycle is enough to bring it back, but, this will avoid the
problem by not touching the panel GPIOs at times we're not meant to.

Signed-off-by: default avatarBen Skeggs <>
parent 4459146d
......@@ -127,12 +127,26 @@ nouveau_connector_ddc_detect(struct drm_connector *connector,
struct nouveau_encoder **pnv_encoder)
struct drm_device *dev = connector->dev;
struct nouveau_connector *nv_connector = nouveau_connector(connector);
struct nouveau_drm *drm = nouveau_drm(dev);
struct nouveau_gpio *gpio = nouveau_gpio(drm->device);
struct nouveau_i2c *i2c = nouveau_i2c(drm->device);
int i;
struct nouveau_i2c_port *port = NULL;
int i, panel = -ENODEV;
/* eDP panels need powering on by us (if the VBIOS doesn't default it
* to on) before doing any AUX channel transactions. LVDS panel power
* is handled by the SOR itself, and not required for LVDS DDC.
if (nv_connector->type == DCB_CONNECTOR_eDP) {
panel = gpio->get(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff);
if (panel == 0) {
gpio->set(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff, 1);
for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
struct nouveau_i2c_port *port = NULL;
struct nouveau_encoder *nv_encoder;
struct drm_mode_object *obj;
int id;
......@@ -150,11 +164,19 @@ nouveau_connector_ddc_detect(struct drm_connector *connector,
port = i2c->find(i2c, nv_encoder->dcb->i2c_index);
if (port && nv_probe_i2c(port, 0x50)) {
*pnv_encoder = nv_encoder;
return port;
port = NULL;
return NULL;
/* eDP panel not detected, restore panel power GPIO to previous
* state to avoid confusing the SOR for other output types.
if (!port && panel == 0)
gpio->set(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff, panel);
return port;
static struct nouveau_encoder *
......@@ -225,15 +225,6 @@ nouveau_display_init(struct drm_device *dev)
if (ret)
return ret;
/* power on internal panel if it's not already. the init tables of
* some vbios default this to off for some reason, causing the
* panel to not work after resume
if (gpio && gpio->get(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff) == 0) {
gpio->set(gpio, 0, DCB_GPIO_PANEL_POWER, 0xff, 1);
/* enable polling for external displays */
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