[Intel-gfx] [PATCH v2] drm/i915/combo_phy: Add Workaround to avoid flicker with HBR3 eDP Panels
Nautiyal, Ankit K
ankit.k.nautiyal at intel.com
Mon Aug 22 11:19:58 UTC 2022
The Bspec:49291 is now changed to reflect that for all platforms the
DCC_MODE will be programmed to DCC_MODE_SELECT_ONCE,
rather than DCC_MODE_SELECT_CONTINUOUSLY.
I will send new patch for the same.
Regards,
Ankit
On 8/10/2022 8:26 PM, Ankit Nautiyal wrote:
> Wa_22012718247 : When Display PHY is configured in continuous
> DCC calibration mode, the DCC (duty cycle correction) for the clock
> erroneously goes through a state where the DCC code is 0x00 when it is
> supposed to be transitioning from 0x10 to 0x0F. This glitch causes a
> distortion in the clock, which leads to a bit error. The issue is known
> to be causing flickering with eDP HBR3 panels.
>
> The work around configures the DCC in one-time-update mode.
> This mode updates the DCC code one time during training and then
> it does not change. This will prevent on-the-fly updates so that the
> glitch does not occur.
>
> v2: Added helper function for DCC_MODE (Imre).
>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> ---
> drivers/gpu/drm/i915/display/intel_combo_phy.c | 16 ++++++++++++++--
> .../gpu/drm/i915/display/intel_combo_phy_regs.h | 1 +
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_combo_phy.c b/drivers/gpu/drm/i915/display/intel_combo_phy.c
> index 64890f39c3cc..b3be0e3ca984 100644
> --- a/drivers/gpu/drm/i915/display/intel_combo_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_combo_phy.c
> @@ -226,6 +226,17 @@ static bool phy_is_master(struct drm_i915_private *dev_priv, enum phy phy)
> return false;
> }
>
> +static u32 tgl_dcc_calibration_mode(struct drm_i915_private *dev_priv)
> +{
> + /* Wa_22012718247:tgl,adlp,adls */
> + if (IS_TIGERLAKE(dev_priv) ||
> + IS_ALDERLAKE_P(dev_priv) ||
> + IS_ALDERLAKE_S(dev_priv))
> + return DCC_MODE_SELECT_ONCE;
> +
> + return DCC_MODE_SELECT_CONTINUOSLY;
> +}
> +
> static bool icl_combo_phy_verify_state(struct drm_i915_private *dev_priv,
> enum phy phy)
> {
> @@ -244,7 +255,7 @@ static bool icl_combo_phy_verify_state(struct drm_i915_private *dev_priv,
>
> ret &= check_phy_reg(dev_priv, phy, ICL_PORT_PCS_DW1_LN(0, phy),
> DCC_MODE_SELECT_MASK,
> - DCC_MODE_SELECT_CONTINUOSLY);
> + tgl_dcc_calibration_mode(dev_priv));
> }
>
> ret &= icl_verify_procmon_ref_values(dev_priv, phy);
> @@ -366,8 +377,9 @@ static void icl_combo_phys_init(struct drm_i915_private *dev_priv)
> intel_de_write(dev_priv, ICL_PORT_TX_DW8_GRP(phy), val);
>
> val = intel_de_read(dev_priv, ICL_PORT_PCS_DW1_LN(0, phy));
> +
> val &= ~DCC_MODE_SELECT_MASK;
> - val |= DCC_MODE_SELECT_CONTINUOSLY;
> + val |= tgl_dcc_calibration_mode(dev_priv);
> intel_de_write(dev_priv, ICL_PORT_PCS_DW1_GRP(phy), val);
> }
>
> diff --git a/drivers/gpu/drm/i915/display/intel_combo_phy_regs.h b/drivers/gpu/drm/i915/display/intel_combo_phy_regs.h
> index 2ed65193ca19..cf46f13401d1 100644
> --- a/drivers/gpu/drm/i915/display/intel_combo_phy_regs.h
> +++ b/drivers/gpu/drm/i915/display/intel_combo_phy_regs.h
> @@ -92,6 +92,7 @@
> #define ICL_PORT_PCS_DW1_LN(ln, phy) _MMIO(_ICL_PORT_PCS_DW_LN(1, ln, phy))
> #define DCC_MODE_SELECT_MASK (0x3 << 20)
> #define DCC_MODE_SELECT_CONTINUOSLY (0x3 << 20)
> +#define DCC_MODE_SELECT_ONCE (0x0 << 20)
> #define COMMON_KEEPER_EN (1 << 26)
> #define LATENCY_OPTIM_MASK (0x3 << 2)
> #define LATENCY_OPTIM_VAL(x) ((x) << 2)
More information about the Intel-gfx
mailing list