From: Matt Roper matthew.d.roper@intel.com
commit c725161924f9a5872a3e53b73345a6026a5c170e upstream.
It wasn't terribly clear from the bspec's wording, but after discussion with the hardware folks, it turns out that we need to preserve the pre-existing contents of the MBUS ABOX control register when initializing a few specific bits.
Bspec: 49213 Bspec: 50096 Fixes: 4cb4585e5a7f ("drm/i915/icl: initialize MBus during display init") Cc: Stanislav Lisovskiy stanislav.lisovskiy@intel.com Signed-off-by: Matt Roper matthew.d.roper@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20200204011032.582737-1-matthe... Reviewed-by: Matt Atwood matthew.s.atwood@intel.com (cherry picked from commit 837b63e6087838d0f1e612d448405419199d8033) Signed-off-by: Jani Nikula jani.nikula@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20200228004320.127142-1-matthe... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/i915/display/intel_display_power.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
--- a/drivers/gpu/drm/i915/display/intel_display_power.c +++ b/drivers/gpu/drm/i915/display/intel_display_power.c @@ -4471,13 +4471,19 @@ static void icl_dbuf_disable(struct drm_
static void icl_mbus_init(struct drm_i915_private *dev_priv) { - u32 val; + u32 mask, val;
- val = MBUS_ABOX_BT_CREDIT_POOL1(16) | - MBUS_ABOX_BT_CREDIT_POOL2(16) | - MBUS_ABOX_B_CREDIT(1) | - MBUS_ABOX_BW_CREDIT(1); + mask = MBUS_ABOX_BT_CREDIT_POOL1_MASK | + MBUS_ABOX_BT_CREDIT_POOL2_MASK | + MBUS_ABOX_B_CREDIT_MASK | + MBUS_ABOX_BW_CREDIT_MASK;
+ val = I915_READ(MBUS_ABOX_CTL); + val &= ~mask; + val |= MBUS_ABOX_BT_CREDIT_POOL1(16) | + MBUS_ABOX_BT_CREDIT_POOL2(16) | + MBUS_ABOX_B_CREDIT(1) | + MBUS_ABOX_BW_CREDIT(1); I915_WRITE(MBUS_ABOX_CTL, val); }