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From: Jani Nikula <jani.nikula@linux.intel.com>
To: Ville Syrjala <ville.syrjala@linux.intel.com>,
	intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH v2 02/19] drm/i915/dsb: Use non-locked register access
Date: Thu, 08 Jun 2023 14:46:29 +0300	[thread overview]
Message-ID: <87edmmrxbe.fsf@intel.com> (raw)
In-Reply-To: <20230606191504.18099-3-ville.syrjala@linux.intel.com>

On Tue, 06 Jun 2023, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Avoid the locking overhead for DSB registers. We don't need the locks
> and intel_dsb_commit() in particular needs to be called from the
> vblank evade critical section and thus needs to be fast.

Mmmh, I always find it slightly puzzling to encounter _fw calls in code,
wondering what the rationale was, and why we can use the _fw variants.

Should we start adding comments explaining why?

BR,
Jani.


>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dsb.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
> index bed058d2c3ac..97e593d9f100 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> @@ -96,7 +96,7 @@ static bool assert_dsb_has_room(struct intel_dsb *dsb)
>  static bool is_dsb_busy(struct drm_i915_private *i915, enum pipe pipe,
>  			enum dsb_id id)
>  {
> -	return intel_de_read(i915, DSB_CTRL(pipe, id)) & DSB_STATUS_BUSY;
> +	return intel_de_read_fw(i915, DSB_CTRL(pipe, id)) & DSB_STATUS_BUSY;
>  }
>  
>  static void intel_dsb_emit(struct intel_dsb *dsb, u32 ldw, u32 udw)
> @@ -243,13 +243,13 @@ void intel_dsb_commit(struct intel_dsb *dsb, bool wait_for_vblank)
>  		return;
>  	}
>  
> -	intel_de_write(dev_priv, DSB_CTRL(pipe, dsb->id),
> -		       (wait_for_vblank ? DSB_WAIT_FOR_VBLANK : 0) |
> -		       DSB_ENABLE);
> -	intel_de_write(dev_priv, DSB_HEAD(pipe, dsb->id),
> -		       i915_ggtt_offset(dsb->vma));
> -	intel_de_write(dev_priv, DSB_TAIL(pipe, dsb->id),
> -		       i915_ggtt_offset(dsb->vma) + tail);
> +	intel_de_write_fw(dev_priv, DSB_CTRL(pipe, dsb->id),
> +			  (wait_for_vblank ? DSB_WAIT_FOR_VBLANK : 0) |
> +			  DSB_ENABLE);
> +	intel_de_write_fw(dev_priv, DSB_HEAD(pipe, dsb->id),
> +			  i915_ggtt_offset(dsb->vma));
> +	intel_de_write_fw(dev_priv, DSB_TAIL(pipe, dsb->id),
> +			  i915_ggtt_offset(dsb->vma) + tail);
>  }
>  
>  void intel_dsb_wait(struct intel_dsb *dsb)
> @@ -266,7 +266,7 @@ void intel_dsb_wait(struct intel_dsb *dsb)
>  	/* Attempt to reset it */
>  	dsb->free_pos = 0;
>  	dsb->ins_start_offset = 0;
> -	intel_de_write(dev_priv, DSB_CTRL(pipe, dsb->id), 0);
> +	intel_de_write_fw(dev_priv, DSB_CTRL(pipe, dsb->id), 0);
>  }
>  
>  /**

-- 
Jani Nikula, Intel Open Source Graphics Center

  reply	other threads:[~2023-06-08 11:46 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-06 19:14 [Intel-gfx] [PATCH v2 00/19] drm/i915: Load LUTs with DSB Ville Syrjala
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 01/19] drm/i915: Constify LUT entries in checker Ville Syrjala
2023-07-05  9:43   ` Manna, Animesh
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 02/19] drm/i915/dsb: Use non-locked register access Ville Syrjala
2023-06-08 11:46   ` Jani Nikula [this message]
2023-09-11 20:22     ` Shankar, Uma
2023-09-12  7:37       ` Jani Nikula
2023-09-12  7:49         ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 03/19] drm/i915/dsb: Dump the DSB command buffer when DSB fails Ville Syrjala
2023-07-11  4:55   ` Manna, Animesh
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 04/19] drm/i915/dsb: Define more DSB bits Ville Syrjala
2023-09-11 20:32   ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 05/19] drm/i915/dsb: Define the contents of some intstructions bit better Ville Syrjala
2023-09-11 20:50   ` Shankar, Uma
2023-09-27 15:38     ` Ville Syrjälä
2023-09-27 16:16       ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 06/19] drm/i915/dsb: Avoid corrupting the first register write Ville Syrjala
2023-07-05  9:39   ` Manna, Animesh
2023-07-05  9:46     ` Manna, Animesh
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 07/19] drm/i915/dsb: Don't use indexed writes when byte enables are not all set Ville Syrjala
2023-07-11  5:00   ` Manna, Animesh
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 08/19] drm/i915/dsb: Introduce intel_dsb_noop() Ville Syrjala
2023-09-11 20:52   ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 09/19] drm/i915/dsb: Introduce intel_dsb_reg_write_masked() Ville Syrjala
2023-09-11 20:55   ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 10/19] drm/i915/dsb: Add support for non-posted DSB registers writes Ville Syrjala
2023-07-11  5:43   ` Manna, Animesh
2023-09-11 21:04     ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 11/19] drm/i915/dsb: Don't use DSB to load the LUTs during full modeset Ville Syrjala
2023-09-11 21:09   ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 12/19] drm/i915/dsb: Load LUTs using the DSB during vblank Ville Syrjala
2023-09-13 16:24   ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 13/19] drm/i915/dsb: Use non-posted register writes for legacy LUT Ville Syrjala
2023-09-13 17:02   ` Shankar, Uma
2023-06-06 19:14 ` [Intel-gfx] [PATCH v2 14/19] drm/i915/dsb: Evade transcoder undelayed vblank when using DSB Ville Syrjala
2023-09-13 17:13   ` Shankar, Uma
2023-06-06 19:15 ` [Intel-gfx] [PATCH v2 15/19] drm/i915: Introduce skl_watermark_max_latency() Ville Syrjala
2023-09-13 17:25   ` Shankar, Uma
2023-06-06 19:15 ` [Intel-gfx] [PATCH v2 16/19] drm/i915: Introudce intel_crtc_scanline_to_hw() Ville Syrjala
2023-09-13 17:37   ` Shankar, Uma
2023-06-06 19:15 ` [Intel-gfx] [PATCH v2 17/19] drm/i915/dsb: Use DEwake to combat PkgC latency Ville Syrjala
2023-09-13 18:08   ` Shankar, Uma
2023-09-27 15:51     ` Ville Syrjälä
2023-09-27 16:11       ` Shankar, Uma
2023-06-06 19:15 ` [Intel-gfx] [PATCH v2 18/19] drm/i915/dsb: Re-instate DSB for LUT updates Ville Syrjala
2023-09-13 18:09   ` Shankar, Uma
2025-01-13 19:26     ` Ed Maste
2025-01-17 14:51       ` Ville Syrjälä
2023-06-06 19:15 ` [Intel-gfx] [PATCH v2 19/19] drm/i915: Do state check for color management changes Ville Syrjala
2023-06-06 22:34 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for drm/i915: Load LUTs with DSB (rev2) Patchwork
2023-06-06 22:34 ` [Intel-gfx] ✗ Fi.CI.SPARSE: " Patchwork
2023-06-06 22:48 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2023-06-07 14:02 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2023-09-27 16:05 ` [Intel-gfx] [PATCH v2 00/19] drm/i915: Load LUTs with DSB Ville Syrjälä

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