On Wed, Jun 03, 2020 at 12:43:07PM -0700, José Roberto de Souza wrote:
> Hours Of Battery Life is a new GEN12+ power-saving feature that allows
> supported motherboards to use a special voltage swing table for eDP
> panels that uses less power.
>
> So here if supported by HW, OEM will set it in VBT and i915 will try
> to train link with HOBL vswing table if link training fails it fall
> back to the original table.
>
> Just not sure if DP compliance should also use this new voltage swing
> table too, cced some folks that worked in DP compliance.
>
> BSpec: 49291
> BSpec: 49399
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Animesh Manna <animesh.manna@xxxxxxxxx>
> Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/display/intel_ddi.c | 48 +++++++++++++++++--
> .../drm/i915/display/intel_display_types.h | 2 +
> .../drm/i915/display/intel_dp_link_training.c | 20 +++++++-
> drivers/gpu/drm/i915/i915_drv.h | 2 +
> drivers/gpu/drm/i915/i915_reg.h | 2 +
> 5 files changed, 69 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 236f3762b6f9..57174a111976 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -692,6 +692,10 @@ static const struct cnl_ddi_buf_trans tgl_combo_phy_ddi_translations_dp_hbr2[] =
> { 0x6, 0x7F, 0x3F, 0x00, 0x00 }, /* 900 900 0.0 */
> };
>
> +static const struct cnl_ddi_buf_trans tgl_combo_phy_ddi_translations_edp_hbr2_hobl[] = {
> + { 0x6, 0x7F, 0x3F, 0x00, 0x00 }
> +};
> +
> static const struct ddi_buf_trans *
> bdw_get_buf_trans_edp(struct drm_i915_private *dev_priv, int *n_entries)
> {
> @@ -2301,14 +2305,51 @@ static void cnl_ddi_vswing_sequence(struct intel_encoder *encoder,
> intel_de_write(dev_priv, CNL_PORT_TX_DW5_GRP(port), val);
> }
>
> +/*
> + * If supported return HOBL vswing table and set registers to enable HOBL
> + * otherwise returns NULL and unset registers to enable HOBL.
> + */
> +static const struct cnl_ddi_buf_trans *
> +hobl_get_combo_buf_trans(struct drm_i915_private *dev_priv,
> + struct intel_encoder *encoder, int type, int rate,
> + u32 level, int *n_entries)
> +{
> + const u32 hobl_en = EDP4K2K_MODE_OVRD_EN | EDP4K2K_MODE_OVRD_OPTIMIZED;
> + enum phy phy = intel_port_to_phy(dev_priv, encoder->port);
> + struct intel_dp *intel_dp;
> +
> + if (!HAS_HOBL(dev_priv) || type != INTEL_OUTPUT_EDP)
> + return NULL;
Not a real fan of the "hobl" name. It just sounds like nonsense. Also
bspec doesn't use that term at all. It only appears in the vbt spec.
Not sure if there's a better one though.
> +
> + intel_dp = enc_to_intel_dp(encoder);
> + if (!intel_dp->try_hobl || rate > 540000) {
> + intel_de_rmw(dev_priv, ICL_PORT_CL_DW10(phy), hobl_en, 0);
I would vote for just doing this programming unconditionally in the normal
sequence.
> + return NULL;
> + }
> +
> + drm_dbg_kms(&dev_priv->drm, "Enabling HOBL in PHY %c\n", phy_name(phy));
> + drm_WARN_ON_ONCE(&dev_priv->drm, level > 0);
> +
> + intel_de_rmw(dev_priv, ICL_PORT_CL_DW10(phy), hobl_en, hobl_en);
> + /* Same table applies to TGL, RKL and DG1 */
> + *n_entries = ARRAY_SIZE(tgl_combo_phy_ddi_translations_edp_hbr2_hobl);
> + return tgl_combo_phy_ddi_translations_edp_hbr2_hobl;
> +}
> +
> static void icl_ddi_combo_vswing_program(struct drm_i915_private *dev_priv,
> - u32 level, enum phy phy, int type,
> - int rate)
> + struct intel_encoder *encoder,
> + u32 level, enum phy phy, int type,
> + int rate)
If we're passing in the encoder then a bunch of this other stuff is
redundant.
> {
> const struct cnl_ddi_buf_trans *ddi_translations = NULL;
> u32 n_entries, val;
> int ln;
>
> + ddi_translations = hobl_get_combo_buf_trans(dev_priv, encoder, type,
> + rate, level, &n_entries);
> + if (ddi_translations)
> + goto hobl_found;
Why not just put it into tgl_get_combo_buf_trans(). Hmm. I guess to not
upset .voltage_max(). This feels a bit hackish, but I don't have better
ideas for now.
> +
> if (INTEL_GEN(dev_priv) >= 12)
> ddi_translations = tgl_get_combo_buf_trans(dev_priv, type, rate,
> &n_entries);
> @@ -2321,6 +2362,7 @@ static void icl_ddi_combo_vswing_program(struct drm_i915_private *dev_priv,
> if (!ddi_translations)
> return;
>
> +hobl_found:
> if (level >= n_entries) {
> drm_dbg_kms(&dev_priv->drm,
> "DDI translation not found for level %d. Using %d instead.",
> @@ -2428,7 +2470,7 @@ static void icl_combo_phy_ddi_vswing_sequence(struct intel_encoder *encoder,
> intel_de_write(dev_priv, ICL_PORT_TX_DW5_GRP(phy), val);
>
> /* 5. Program swing and de-emphasis */
> - icl_ddi_combo_vswing_program(dev_priv, level, phy, type, rate);
> + icl_ddi_combo_vswing_program(dev_priv, encoder, level, phy, type, rate);
>
> /* 6. Set training enable to trigger update */
> val = intel_de_read(dev_priv, ICL_PORT_TX_DW5_LN0(phy));
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 4b0aaa3081c9..f8943b67819d 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1375,6 +1375,8 @@ struct intel_dp {
>
> /* Display stream compression testing */
> bool force_dsc_en;
> +
> + bool try_hobl;
> };
>
> enum lspcon_vendor {
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index b9e4ee2dbddc..88f366bb28d7 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -52,12 +52,24 @@ static u8 dp_voltage_max(u8 preemph)
> void intel_dp_get_adjust_train(struct intel_dp *intel_dp,
> const u8 link_status[DP_LINK_STATUS_SIZE])
> {
> + struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> u8 v = 0;
> u8 p = 0;
> int lane;
> u8 voltage_max;
> u8 preemph_max;
>
> + if (intel_dp->try_hobl) {
> + /*
> + * Do not adjust, try now with the regular table using VSwing 0
> + * and pre-emp 0
> + */
What if the sink is still asking for vswing 0 + preemph 0? The spec is
rather ambiguous when it comes to this stuff.
The table also doesn't specify the vswing/preemph for which we should
use this optimized value. Your interpretation of 0+0 seems like the most
sensible thing, but given that the VBT can also specifiy the fast link
training vswing/preemph as something else (and maybe there was also
something like this for normal link training?) I'm not 100% sure.
Hmm. Actually noticed that all the eDP tables are missing the
vswing/preemph levels (they do have the raw mV/dB values but not the
DP spec levels). I filed a few issues in the hopes of clarification.
> + intel_dp->try_hobl = false;
> + drm_dbg_kms(&dev_priv->drm, "HOBL vswing table failed link "
> + "training, switching back to regular table\n");
> + return;
> + }
> +
> for (lane = 0; lane < intel_dp->lane_count; lane++) {
> v = max(v, drm_dp_get_adjust_request_voltage(link_status, lane));
> p = max(p, drm_dp_get_adjust_request_pre_emphasis(link_status, lane));
> @@ -103,9 +115,13 @@ intel_dp_set_link_train(struct intel_dp *intel_dp,
> }
>
> static bool
> -intel_dp_reset_link_train(struct intel_dp *intel_dp,
> - u8 dp_train_pat)
> +intel_dp_reset_link_train(struct intel_dp *intel_dp, u8 dp_train_pat)
> {
> + struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> +
> + if (intel_dp_is_edp(intel_dp) && dev_priv->vbt.edp.hobl)
> + intel_dp->try_hobl = true;
If it failed once does it make sense to keep trying to use it?
> +
> memset(intel_dp->train_set, 0, sizeof(intel_dp->train_set));
> intel_dp_set_signal_levels(intel_dp);
> return intel_dp_set_link_train(intel_dp, dp_train_pat);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 2336c9231eef..c7e7df17eef2 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1687,6 +1687,8 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
> #define INTEL_DISPLAY_ENABLED(dev_priv) \
> (drm_WARN_ON(&(dev_priv)->drm, !HAS_DISPLAY(dev_priv)), !i915_modparams.disable_display)
>
> +#define HAS_HOBL(dev_priv) (INTEL_GEN(dev_priv) >= 12)
> +
> static inline bool intel_vtd_active(void)
> {
> #ifdef CONFIG_INTEL_IOMMU
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 578cfe11cbb9..d4611171f075 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1896,6 +1896,8 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
> #define PWR_DOWN_LN_3_1_0 (0xb << 4)
> #define PWR_DOWN_LN_MASK (0xf << 4)
> #define PWR_DOWN_LN_SHIFT 4
> +#define EDP4K2K_MODE_OVRD_EN (1 << 3)
> +#define EDP4K2K_MODE_OVRD_OPTIMIZED (1 << 2)
>
> #define ICL_PORT_CL_DW12(phy) _MMIO(_ICL_PORT_CL_DW(12, phy))
> #define ICL_LANE_ENABLE_AUX (1 << 0)
> --
> 2.27.0
--
Ville Syrjälä
Intel
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