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Subject[PATCH 4/9] drm/i915: Check eDP power when doing aux channel communications
Date
Verify that the eDP VDD is on, either with the panel being on or with
the VDD force-on bit being set.

This demonstrates that in many instances, VDD is not on when needed,
which leads to failed EDID communications.

Signed-off-by: Keith Packard <keithp@keithp.com>
---
drivers/gpu/drm/i915/intel_dp.c | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 8ab2a88..3b29a6f 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -279,6 +279,24 @@ intel_hrawclk(struct drm_device *dev)
}
}

+static void
+intel_dp_check_edp(struct intel_dp *intel_dp)
+{
+ struct drm_device *dev = intel_dp->base.base.dev;
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ u32 pp_status, pp_control;
+ if (!is_edp(intel_dp))
+ return;
+ pp_status = I915_READ(PCH_PP_STATUS);
+ pp_control = I915_READ(PCH_PP_CONTROL);
+ if ((pp_status & PP_ON) == 0 && (pp_control & EDP_FORCE_VDD) == 0) {
+ WARN(1, "eDP powered off while attempting aux channel communication.\n");
+ DRM_DEBUG_KMS("Status 0x%08x Control 0x%08x\n",
+ pp_status,
+ I915_READ(PCH_PP_CONTROL));
+ }
+}
+
static int
intel_dp_aux_ch(struct intel_dp *intel_dp,
uint8_t *send, int send_bytes,
@@ -295,6 +313,7 @@ intel_dp_aux_ch(struct intel_dp *intel_dp,
uint32_t aux_clock_divider;
int try, precharge;

+ intel_dp_check_edp(intel_dp);
/* The clock divider is based off the hrawclk,
* and would like to run at 2MHz. So, take the
* hrawclk value and divide by 2 and use that
@@ -408,6 +427,7 @@ intel_dp_aux_native_write(struct intel_dp *intel_dp,
int msg_bytes;
uint8_t ack;

+ intel_dp_check_edp(intel_dp);
if (send_bytes > 16)
return -1;
msg[0] = AUX_NATIVE_WRITE << 4;
@@ -450,6 +470,7 @@ intel_dp_aux_native_read(struct intel_dp *intel_dp,
uint8_t ack;
int ret;

+ intel_dp_check_edp(intel_dp);
msg[0] = AUX_NATIVE_READ << 4;
msg[1] = address >> 8;
msg[2] = address & 0xff;
@@ -493,6 +514,7 @@ intel_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
int reply_bytes;
int ret;

+ intel_dp_check_edp(intel_dp);
/* Set up the command byte */
if (mode & MODE_I2C_READ)
msg[0] = AUX_I2C_READ << 4;
--
1.7.6.3


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