On Wed, 29 Jan 2025, Imre Deak <imre.deak@xxxxxxxxx> wrote:
> From: Imre Deak <imre.deak@xxxxxxxxx>
>
> Fix the port width programming in the DDI_BUF_CTL register on MTLP+,
> where this had an off-by-one error.
Fixes: b66a8abaa48a ("drm/i915/display/mtl: Fill port width in DDI_BUF_/TRANS_DDI_FUNC_/PORT_BUF_CTL for HDMI")
Cc: <stable@xxxxxxxxxxxxxxx> # v6.5+
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
However, if this gets backported, it'll break DSI. Patch 1 needs to
accompany it.
Either add the same Fixes line to patch 1, or squash patches 1-2
together.
>
> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 2 +-
> drivers/gpu/drm/i915/i915_reg.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index dc319f37b1be9..36e7dde422d37 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -3501,7 +3501,7 @@ static void intel_ddi_enable_hdmi(struct intel_atomic_state *state,
> intel_de_rmw(dev_priv, XELPDP_PORT_BUF_CTL1(dev_priv, port),
> XELPDP_PORT_WIDTH_MASK | XELPDP_PORT_REVERSAL, port_buf);
>
> - buf_ctl |= DDI_PORT_WIDTH(lane_count);
> + buf_ctl |= DDI_PORT_WIDTH(crtc_state->lane_count);
>
> if (DISPLAY_VER(dev_priv) >= 20)
> buf_ctl |= XE2LPD_DDI_BUF_D2D_LINK_ENABLE;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 03da51b03fb90..04e47d0a8ab92 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -3635,7 +3635,7 @@ enum skl_power_gate {
> #define DDI_BUF_IS_IDLE (1 << 7)
> #define DDI_BUF_CTL_TC_PHY_OWNERSHIP REG_BIT(6)
> #define DDI_A_4_LANES (1 << 4)
> -#define DDI_PORT_WIDTH(width) (((width) - 1) << 1)
> +#define DDI_PORT_WIDTH(width) (((width) == 3 ? 4 : ((width) - 1)) << 1)
> #define DDI_PORT_WIDTH_MASK (7 << 1)
> #define DDI_PORT_WIDTH_SHIFT 1
> #define DDI_INIT_DISPLAY_DETECTED (1 << 0)
--
Jani Nikula, Intel
