According to the BSpec update, bit 7 of PORT_CL1CM_DW0 register needs to be
checked to ensure that the register is in accessible state.
Also, based on a BSpec update, changing the timeout value to
check iphypwrgood, from 10ms to wait for up to 100us.
v2: [Ville] use wait_for_us instead of the atomic call.
v3: [Jani/Imre] read register only once
Signed-off-by: Vandana Kannan <vandana.kannan@xxxxxxxxx>
Reported-by: Philippe Lecluse <Philippe.Lecluse@xxxxxxxxx>
Cc: Deak, Imre <imre.deak@xxxxxxxxx>
Cc: Nikula, Jani <jani.nikula@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_ddi.c | 13 +++++++++++--
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 7dfc400..9a02bfc 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1318,6 +1318,7 @@ enum skl_disp_power_wells {
#define _PORT_CL1CM_DW0_A 0x162000
#define _PORT_CL1CM_DW0_BC 0x6C000
#define PHY_POWER_GOOD (1 << 16)
+#define PHY_RESERVED (1 << 7)
#define BXT_PORT_CL1CM_DW0(phy) _BXT_PHY((phy), _PORT_CL1CM_DW0_BC, \
_PORT_CL1CM_DW0_A)
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index 62de9f4..4a8f504 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -2669,9 +2669,18 @@ static void broxton_phy_init(struct drm_i915_private *dev_priv,
val |= GT_DISPLAY_POWER_ON(phy);
I915_WRITE(BXT_P_CR_GT_DISP_PWRON, val);
- /* Considering 10ms timeout until BSpec is updated */
- if (wait_for(I915_READ(BXT_PORT_CL1CM_DW0(phy)) & PHY_POWER_GOOD, 10))
+ /*
+ * The PHY registers start out inaccessible and respond to reads with
+ * all 1s. Eventually they become accessible as they power up, then
+ * the reserved bit will give the default 0. Poll on the reserved bit
+ * becoming 0 to find when the PHY is accessible.
+ * HW team confirmed that the time to reach phypowergood status is
+ * anywhere between 50 us and 100us.
+ */
+ if (wait_for_us(((I915_READ(BXT_PORT_CL1CM_DW0(phy)) &
+ (PHY_RESERVED | PHY_POWER_GOOD)) == PHY_POWER_GOOD), 100)) {
DRM_ERROR("timeout during PHY%d power on\n", phy);
+ }
for (port = (phy == DPIO_PHY0 ? PORT_B : PORT_A);
port <= (phy == DPIO_PHY0 ? PORT_C : PORT_A); port++) {
--
1.9.1
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