On Thu, Feb 14, 2019 at 09:22:18PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> DP CRCs don't really work on g4x. If you want any CRCs on DP you must
> select the CRC source before the port is enabled, otherwise the CRC
> source select bits simply ignore any writes to them. And once the port
> is enabled we mustn't change the CRC source select until the port is
> disabled. That almost works, but not quite :( Eventually the CRC source
> select bits get permanently stuck one way or the other, and after that
> a reboot (or possibly a display reset) is needed to get working CRCs
> on that pipe (not matter which CRC source we try to use).
>
> Additionally the DFT scrambler reset bits we're trying to use don't
> seem to exist on g4x. There are some potentially relevant looking bits
> in the pipe registers, but when I tried it I got stable looking CRCs
> without setting any bits for this.
>
> If there is a way to make DP CRCs work reliably on g4x, I wasn't
> able to find it. So let's just remove the broken code we have.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_pipe_crc.c | 80 ++++-----------------------
> 1 file changed, 11 insertions(+), 69 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pipe_crc.c b/drivers/gpu/drm/i915/intel_pipe_crc.c
> index fe0ff89b980b..66bb7b031537 100644
> --- a/drivers/gpu/drm/i915/intel_pipe_crc.c
> +++ b/drivers/gpu/drm/i915/intel_pipe_crc.c
> @@ -191,8 +191,6 @@ static int i9xx_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
> enum intel_pipe_crc_source *source,
> u32 *val)
> {
> - bool need_stable_symbols = false;
> -
> if (*source == INTEL_PIPE_CRC_SOURCE_AUTO) {
> int ret = i9xx_pipe_crc_auto_source(dev_priv, pipe, source);
> if (ret)
> @@ -208,56 +206,23 @@ static int i9xx_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
> return -EINVAL;
> *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_TV_PRE;
> break;
> - case INTEL_PIPE_CRC_SOURCE_DP_B:
> - if (!IS_G4X(dev_priv))
> - return -EINVAL;
> - *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_B_G4X;
> - need_stable_symbols = true;
> - break;
> - case INTEL_PIPE_CRC_SOURCE_DP_C:
> - if (!IS_G4X(dev_priv))
> - return -EINVAL;
> - *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_C_G4X;
> - need_stable_symbols = true;
> - break;
> - case INTEL_PIPE_CRC_SOURCE_DP_D:
> - if (!IS_G4X(dev_priv))
> - return -EINVAL;
> - *val = PIPE_CRC_ENABLE | PIPE_CRC_SOURCE_DP_D_G4X;
> - need_stable_symbols = true;
> - break;
> case INTEL_PIPE_CRC_SOURCE_NONE:
> *val = 0;
> break;
> default:
> + /*
> + * The DP CRC source doesn't work on g4x.
> + * It can be made to work to some degree by selecting
> + * the correct CRC source before the port is enabled,
> + * and not touching the CRC source bits again until
> + * the port is disabled. But even then the bits
> + * eventually get stuck and a reboot is needed to get
> + * working CRCs on the pipe again. Let's simply
> + * refuse to use DP CRCs on g4x.
> + */
> return -EINVAL;
is this the right return now? maybe ENOENT?
(just brainstorming without looking to igt tests)
But I know how terrible unreliable crcs are and this patch
looks the right way, so:
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> }
>
> - /*
> - * When the pipe CRC tap point is after the transcoders we need
> - * to tweak symbol-level features to produce a deterministic series of
> - * symbols for a given frame. We need to reset those features only once
> - * a frame (instead of every nth symbol):
> - * - DC-balance: used to ensure a better clock recovery from the data
> - * link (SDVO)
> - * - DisplayPort scrambling: used for EMI reduction
> - */
> - if (need_stable_symbols) {
> - u32 tmp = I915_READ(PORT_DFT2_G4X);
> -
> - WARN_ON(!IS_G4X(dev_priv));
> -
> - I915_WRITE(PORT_DFT_I9XX,
> - I915_READ(PORT_DFT_I9XX) | DC_BALANCE_RESET);
> -
> - if (pipe == PIPE_A)
> - tmp |= PIPE_A_SCRAMBLE_RESET;
> - else
> - tmp |= PIPE_B_SCRAMBLE_RESET;
> -
> - I915_WRITE(PORT_DFT2_G4X, tmp);
> - }
> -
> return 0;
> }
>
> @@ -282,24 +247,6 @@ static void vlv_undo_pipe_scramble_reset(struct drm_i915_private *dev_priv,
> if (!(tmp & PIPE_SCRAMBLE_RESET_MASK))
> tmp &= ~DC_BALANCE_RESET_VLV;
> I915_WRITE(PORT_DFT2_G4X, tmp);
> -
> -}
> -
> -static void g4x_undo_pipe_scramble_reset(struct drm_i915_private *dev_priv,
> - enum pipe pipe)
> -{
> - u32 tmp = I915_READ(PORT_DFT2_G4X);
> -
> - if (pipe == PIPE_A)
> - tmp &= ~PIPE_A_SCRAMBLE_RESET;
> - else
> - tmp &= ~PIPE_B_SCRAMBLE_RESET;
> - I915_WRITE(PORT_DFT2_G4X, tmp);
> -
> - if (!(tmp & PIPE_SCRAMBLE_RESET_MASK)) {
> - I915_WRITE(PORT_DFT_I9XX,
> - I915_READ(PORT_DFT_I9XX) & ~DC_BALANCE_RESET);
> - }
> }
>
> static int ilk_pipe_crc_ctl_reg(enum intel_pipe_crc_source *source,
> @@ -485,9 +432,6 @@ static int i9xx_crc_source_valid(struct drm_i915_private *dev_priv,
> switch (source) {
> case INTEL_PIPE_CRC_SOURCE_PIPE:
> case INTEL_PIPE_CRC_SOURCE_TV:
> - case INTEL_PIPE_CRC_SOURCE_DP_B:
> - case INTEL_PIPE_CRC_SOURCE_DP_C:
> - case INTEL_PIPE_CRC_SOURCE_DP_D:
> case INTEL_PIPE_CRC_SOURCE_NONE:
> return 0;
> default:
> @@ -612,9 +556,7 @@ int intel_crtc_set_crc_source(struct drm_crtc *crtc, const char *source_name)
> POSTING_READ(PIPE_CRC_CTL(crtc->index));
>
> if (!source) {
> - if (IS_G4X(dev_priv))
> - g4x_undo_pipe_scramble_reset(dev_priv, crtc->index);
> - else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> + if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
> vlv_undo_pipe_scramble_reset(dev_priv, crtc->index);
> else if ((IS_HASWELL(dev_priv) ||
> IS_BROADWELL(dev_priv)) && crtc->index == PIPE_A)
> --
> 2.19.2
>
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