> Subject: [PATCH v2 08/10] drm/i915/alpm: Enable MAC Transmitting LFPS for
> LT phy
> 
> Enable LT phy for transmitting LFPS during aux-less alpm.

Not really !
You are actually enabling MAC to transmit LFPS via LT PHY

> 
> Cc: Jouni Högander <[email protected]>
> Signed-off-by: Animesh Manna <[email protected]>
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c      |  5 ++-
>  drivers/gpu/drm/i915/display/intel_lt_phy.c   | 35 +++++++++++++++++++
>  drivers/gpu/drm/i915/display/intel_lt_phy.h   |  2 ++
>  .../gpu/drm/i915/display/intel_lt_phy_regs.h  |  3 ++
>  4 files changed, 44 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c
> b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 733ef4559131..f6450ebea2a8 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -3781,7 +3781,10 @@ static void mtl_ddi_prepare_link_retrain(struct
> intel_dp *intel_dp,
>        *     ii. Enable MAC Transmits LFPS in the "PHY Common Control 0"
> PIPE
>        *         register
>        */
> -     intel_lnl_mac_transmit_lfps(encoder, crtc_state);
> +     if (HAS_LT_PHY(display))
> +             intel_xe3plpd_mac_transmit_lfps(encoder, crtc_state);
> +     else
> +             intel_lnl_mac_transmit_lfps(encoder, crtc_state);
>  }
> 
>  static void intel_ddi_prepare_link_retrain(struct intel_dp *intel_dp, diff 
> --git
> a/drivers/gpu/drm/i915/display/intel_lt_phy.c
> b/drivers/gpu/drm/i915/display/intel_lt_phy.c
> index af48d6cde226..87659a9d9847 100644
> --- a/drivers/gpu/drm/i915/display/intel_lt_phy.c
> +++ b/drivers/gpu/drm/i915/display/intel_lt_phy.c
> @@ -7,6 +7,7 @@
> 
>  #include "i915_reg.h"
>  #include "i915_utils.h"
> +#include "intel_alpm.h"
>  #include "intel_cx0_phy.h"
>  #include "intel_cx0_phy_regs.h"
>  #include "intel_ddi.h"
> @@ -1998,3 +1999,37 @@ void intel_xe3plpd_pll_disable(struct
> intel_encoder *encoder)
>               intel_lt_phy_pll_disable(encoder);
> 
>  }
> +
> +/*
> + * According to HAS we need to enable MAC Transmitting LFPS in the "PHY
> +Common
> + * Control 0" PIPE register in case of AUX Less ALPM is going to be
> +used. This
> + * function is doing that and is called by link retrain sequence.
> + */
> +void intel_xe3plpd_mac_transmit_lfps(struct intel_encoder *encoder,
> +                                  const struct intel_crtc_state *crtc_state) 
> {
> +     intel_wakeref_t wakeref;
> +     int i;
> +     u8 owned_lane_mask;
> +
> +     if (!intel_alpm_is_alpm_aux_less(enc_to_intel_dp(encoder),
> crtc_state))
> +             return;
> +
> +     owned_lane_mask = intel_lt_phy_get_owned_lane_mask(encoder);
> +
> +     wakeref = intel_lt_phy_transaction_begin(encoder);
> +
> +     for (i = 0; i < 4; i++) {
> +             int tx = i % 2 + 1;
> +             u8 lane_mask = i < 2 ? INTEL_LT_PHY_LANE0 :
> INTEL_LT_PHY_LANE1;
> +
> +             if (!(owned_lane_mask & lane_mask))
> +                     continue;
> +
> +             intel_lt_phy_rmw(encoder, lane_mask, LT_PHY_CMN_CTL(tx,
> 0),
> +                              LT_PHY_CMN_LFPS_ENABLE,
> +                              LT_PHY_CMN_LFPS_ENABLE,
> MB_WRITE_COMMITTED);

All this loop not needed you have no dependency on the transmitter
LT_PHY_CMN_CTL0 is only one of its kind at address 0x800.
A simple lt_phy_rmw to enable LT_PHY_CMN_LFPS_ENABLE should work

> +     }
> +
> +     intel_lt_phy_transaction_end(encoder, wakeref); }
> diff --git a/drivers/gpu/drm/i915/display/intel_lt_phy.h
> b/drivers/gpu/drm/i915/display/intel_lt_phy.h
> index a538d4c69210..7391dd7252d7 100644
> --- a/drivers/gpu/drm/i915/display/intel_lt_phy.h
> +++ b/drivers/gpu/drm/i915/display/intel_lt_phy.h
> @@ -38,6 +38,8 @@ void intel_lt_phy_pll_state_verify(struct
> intel_atomic_state *state,  void intel_xe3plpd_pll_enable(struct intel_encoder
> *encoder,
>                             const struct intel_crtc_state *crtc_state);  void
> intel_xe3plpd_pll_disable(struct intel_encoder *encoder);
> +void intel_xe3plpd_mac_transmit_lfps(struct intel_encoder *encoder,
> +                                  const struct intel_crtc_state *crtc_state);
> 
>  #define HAS_LT_PHY(display) (DISPLAY_VER(display) >= 35)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_lt_phy_regs.h
> b/drivers/gpu/drm/i915/display/intel_lt_phy_regs.h
> index 9223487d764e..8a19b7cb59dc 100644
> --- a/drivers/gpu/drm/i915/display/intel_lt_phy_regs.h
> +++ b/drivers/gpu/drm/i915/display/intel_lt_phy_regs.h
> @@ -36,6 +36,9 @@
>  #define LT_PHY_TXY_CTL10_MAC(idx)    _MMIO(LT_PHY_TXY_CTL10(idx))
>  #define  LT_PHY_TX_LANE_ENABLE               REG_BIT8(0)
> 
> +#define LT_PHY_CMN_CTL(idx, control) (0x800 + (0x200 * ((idx) - 1)) +
> (control))

No need should only be 0x800
And name should be LT_PHY_CMN_CTL_0

Regards,
Suraj Kandpal

> +#define  LT_PHY_CMN_LFPS_ENABLE              REG_BIT8(1)
> +
>  /* LT Phy Vendor Register */
>  #define LT_PHY_VDR_0_CONFIG  0xC02
>  #define  LT_PHY_VDR_DP_PLL_ENABLE    REG_BIT(7)
> --
> 2.29.0

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