[PATCH] drm/amd/display: Add get_dig_frontend implementation for DCEx

[Alex Deucher]

On Tue, Dec 15, 2020 at 10:45 AM Rodrigo Siqueira
<Rodrigo.Siqueira at amd.com> wrote:
>
> Some old ASICs might not implement/require get_dig_frontend helper; in
> this scenario, we can have a NULL pointer exception when we try to call
> it inside vbios disable operation. For example, this situation might
> happen when using Polaris12 with an eDP panel. This commit avoids this
> situation by adding a specific get_dig_frontend implementation for DCEx.
>
> Cc: Alex Deucher <alexander.deucher at amd.com>
> Cc: Borislav Petkov <bp at alien8.de>
> Cc: Harry Wentland <Harry.Wentland at amd.com>
> Cc: Nicholas Kazlauskas <Nicholas.Kazlauskas at amd.com>
> Cc: Chiawen Huang <chiawen.huang at amd.com>
> Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira at amd.com>
> ---
>  .../drm/amd/display/dc/dce/dce_link_encoder.c | 43 ++++++++++++++++++-
>  .../drm/amd/display/dc/dce/dce_link_encoder.h |  2 +
>  2 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c
> index 4592ccdfa9b0..f355cd1e9090 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.c
> @@ -120,6 +120,7 @@ static const struct link_encoder_funcs dce110_lnk_enc_funcs = {
>         .is_dig_enabled = dce110_is_dig_enabled,
>         .destroy = dce110_link_encoder_destroy,
>         .get_max_link_cap = dce110_link_encoder_get_max_link_cap,
> +       .get_dig_frontend = dce110_get_dig_frontend,
>  };
>
>  static enum bp_result link_transmitter_control(
> @@ -235,6 +236,45 @@ static void set_link_training_complete(
>
>  }
>
> +unsigned int dce110_get_dig_frontend(struct link_encoder *enc)
> +{
> +       struct dce110_link_encoder *enc110 = TO_DCE110_LINK_ENC(enc);
> +       u32 value;
> +       enum engine_id result;
> +
> +       REG_GET(DIG_BE_CNTL, DIG_FE_SOURCE_SELECT, &value);
> +
> +       switch (value) {
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGA:
> +               result = ENGINE_ID_DIGA;
> +               break;
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGB:
> +               result = ENGINE_ID_DIGB;
> +               break;
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGC:
> +               result = ENGINE_ID_DIGC;
> +               break;
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGD:
> +               result = ENGINE_ID_DIGD;
> +               break;
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGE:
> +               result = ENGINE_ID_DIGE;
> +               break;
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGF:
> +               result = ENGINE_ID_DIGF;
> +               break;
> +       case DCE110_DIG_FE_SOURCE_SELECT_DIGG:
> +               result = ENGINE_ID_DIGG;
> +               break;
> +       default:
> +               // invalid source select DIG
> +               ASSERT(false);
> +               result = ENGINE_ID_UNKNOWN;

Do we really want the ASSERT?  The same function for DCN asserts all
the time on newer APUs if the register has it's default value (e.g.,
if a particular output was not used by the vbios).  IMHO, we should
remove the assert both here and for DCN.

Alex


> +       }
> +
> +       return result;
> +}
> +
>  void dce110_link_encoder_set_dp_phy_pattern_training_pattern(
>         struct link_encoder *enc,
>         uint32_t index)
> @@ -1665,7 +1705,8 @@ static const struct link_encoder_funcs dce60_lnk_enc_funcs = {
>         .disable_hpd = dce110_link_encoder_disable_hpd,
>         .is_dig_enabled = dce110_is_dig_enabled,
>         .destroy = dce110_link_encoder_destroy,
> -       .get_max_link_cap = dce110_link_encoder_get_max_link_cap
> +       .get_max_link_cap = dce110_link_encoder_get_max_link_cap,
> +       .get_dig_frontend = dce110_get_dig_frontend
>  };
>
>  void dce60_link_encoder_construct(
> diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.h b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.h
> index cb714a48b171..fc6ade824c23 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.h
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_link_encoder.h
> @@ -295,6 +295,8 @@ void dce110_link_encoder_connect_dig_be_to_fe(
>         enum engine_id engine,
>         bool connect);
>
> +unsigned int dce110_get_dig_frontend(struct link_encoder *enc);
> +
>  void dce110_link_encoder_set_dp_phy_pattern_training_pattern(
>         struct link_encoder *enc,
>         uint32_t index);
> --
> 2.29.2
>
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