Re: [PATCH 08/15] drm/i915/display: Refactor enable_joiner_pipes

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Sep 26, 2024 at 06:45:14PM +0530, Nautiyal, Ankit K wrote:
> 
> On 9/26/2024 4:49 PM, Ville Syrjälä wrote:
> > On Thu, Sep 26, 2024 at 12:56:31PM +0530, Ankit Nautiyal wrote:
> >> Pass the current pipe into enabled_joiner_pipes(), and let it figure out
> >> the proper bitmasks for us. Since the enabled_joiner_pipes now gets the
> >> primary and secondary pipe wrt a given pipe, the helpers
> >> to get primary pipe and secondary pipes are no longer required.
> >>
> >> v2:
> >> -Simplify helper get_joiner_primary_pipes. (Ville)
> >> -Nuke get_joiner_secondary_pipes. (Ville)
> >> -Add more drm_WARNs final primary/secondary pipes. (Ville)
> >> v3:
> >> -Drop ultrajoiner stuff and add it in subsequent patches. (Ville)
> >>
> >> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
> >> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> ---
> >>   drivers/gpu/drm/i915/display/intel_display.c | 89 ++++++++++----------
> >>   1 file changed, 44 insertions(+), 45 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> >> index 2d6260c3bca5..ea259b142786 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_display.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> >> @@ -3663,7 +3663,15 @@ static u8 expected_bigjoiner_secondary_pipes(u8 bigjoiner_primary_pipes)
> >>   	return expected_secondary_pipes(bigjoiner_primary_pipes, 2);
> >>   }
> >>   
> >> +static u8 get_joiner_primary_pipe(enum pipe pipe, u8 primary_pipes)
> >> +{
> >> +	primary_pipes &= GENMASK(pipe, 0);
> >> +
> >> +	return primary_pipes ? BIT(fls(primary_pipes) - 1) : 0;
> >> +}
> >> +
> >>   static void enabled_joiner_pipes(struct drm_i915_private *dev_priv,
> >> +				 enum pipe pipe,
> >>   				 u8 *primary_pipes, u8 *secondary_pipes)
> >>   {
> >>   	struct intel_display *display = to_intel_display(&dev_priv->drm);
> >> @@ -3703,45 +3711,38 @@ static void enabled_joiner_pipes(struct drm_i915_private *dev_priv,
> >>   		 expected_uncompressed_joiner_secondary_pipes(primary_uncompressed_joiner_pipes),
> >>   		 secondary_uncompressed_joiner_pipes);
> >>   
> >> -	*primary_pipes = primary_uncompressed_joiner_pipes | primary_bigjoiner_pipes;
> >> -
> >> -	*secondary_pipes = secondary_uncompressed_joiner_pipes | secondary_bigjoiner_pipes;
> >> -
> >> -	/* Joiner pipes should always be consecutive primary and secondary */
> >> -	drm_WARN(display->drm, *secondary_pipes != *primary_pipes << 1,
> >> -		 "Joiner misconfigured (primary pipes %#x, secondary pipes %#x)\n",
> >> -		 *primary_pipes, *secondary_pipes);
> >> -}
> >> -
> >> -static enum pipe get_joiner_primary_pipe(enum pipe pipe, u8 primary_pipes, u8 secondary_pipes)
> >> -{
> >> -	if ((secondary_pipes & BIT(pipe)) == 0)
> >> -		return pipe;
> >> -
> >> -	/* ignore everything above our pipe */
> >> -	primary_pipes &= ~GENMASK(7, pipe);
> >> -
> >> -	/* highest remaining bit should be our primary pipe */
> >> -	return fls(primary_pipes) - 1;
> >> -}
> >> -
> >> -static u8 get_joiner_secondary_pipes(enum pipe pipe, u8 primary_pipes, u8 secondary_pipes)
> >> -{
> >> -	enum pipe primary_pipe, next_primary_pipe;
> >> -
> >> -	primary_pipe = get_joiner_primary_pipe(pipe, primary_pipes, secondary_pipes);
> >> -
> >> -	if ((primary_pipes & BIT(primary_pipe)) == 0)
> >> -		return 0;
> >> -
> >> -	/* ignore our primary pipe and everything below it */
> >> -	primary_pipes &= ~GENMASK(primary_pipe, 0);
> >> -	/* make sure a high bit is set for the ffs() */
> >> -	primary_pipes |= BIT(7);
> >> -	/* lowest remaining bit should be the next primary pipe */
> >> -	next_primary_pipe = ffs(primary_pipes) - 1;
> >> -
> >> -	return secondary_pipes & GENMASK(next_primary_pipe - 1, primary_pipe);
> >> +	*primary_pipes = 0;
> >> +	*secondary_pipes = 0;
> >> +
> >> +	if (uncompressed_joiner_pipes & BIT(pipe)) {
> >> +		*primary_pipes = get_joiner_primary_pipe(pipe, primary_uncompressed_joiner_pipes);
> >> +		*secondary_pipes = secondary_uncompressed_joiner_pipes &
> >> +				   expected_uncompressed_joiner_secondary_pipes(*primary_pipes);
> >> +
> >> +		drm_WARN(display->drm,
> >> +			 expected_uncompressed_joiner_secondary_pipes(*primary_pipes) !=
> >> +			 *secondary_pipes,
> >> +			 "Wrong uncompressed joiner secondary pipes for primary_pipes %#x (expected %#x, current %#x)\n",
> >> +			 *primary_pipes,
> >> +			 expected_uncompressed_joiner_secondary_pipes(*primary_pipes),
> >> +			 *secondary_pipes);
> >> +		return;
> >> +	}
> >> +
> >> +	if (bigjoiner_pipes & BIT(pipe)) {
> >> +		*primary_pipes = get_joiner_primary_pipe(pipe, primary_bigjoiner_pipes);
> >> +		*secondary_pipes = secondary_bigjoiner_pipes &
> >> +				   expected_bigjoiner_secondary_pipes(*primary_pipes);
> >> +
> >> +		drm_WARN(display->drm,
> >> +			 expected_bigjoiner_secondary_pipes(*primary_pipes) !=
> >> +			 *secondary_pipes,
> >> +			 "Wrong bigjoiner secondary pipes for primary_pipes %#x (expected %#x, current %#x)\n",
> >> +			 *primary_pipes,
> >> +			 expected_bigjoiner_secondary_pipes(*primary_pipes),
> >> +			 *secondary_pipes);
> >> +		return;
> >> +	}
> >>   }
> >>   
> >>   static u8 hsw_panel_transcoders(struct drm_i915_private *i915)
> >> @@ -3813,10 +3814,10 @@ static u8 hsw_enabled_transcoders(struct intel_crtc *crtc)
> >>   		enabled_transcoders |= BIT(cpu_transcoder);
> >>   
> >>   	/* joiner secondary -> consider the primary pipe's transcoder as well */
> >> -	enabled_joiner_pipes(dev_priv, &primary_pipes, &secondary_pipes);
> >> +	enabled_joiner_pipes(dev_priv, crtc->pipe, &primary_pipes, &secondary_pipes);
> >>   	if (secondary_pipes & BIT(crtc->pipe)) {
> >>   		cpu_transcoder = (enum transcoder)
> >> -			get_joiner_primary_pipe(crtc->pipe, primary_pipes, secondary_pipes);
> >> +			ffs(get_joiner_primary_pipe(crtc->pipe, primary_pipes)) - 1;
> > The get_joiner_primary_pipe() shouldn't be needed here since
> > enabled_joiner_pipes() guarantees that only one bit is set.
> 
> 
> I agree. Additionally, I was considering changing the input variable 
> name from `primary_pipes` to `primary_pipe` in enabled_joiner_pipes for 
> clarity. Does that make sense?

Probably a good idea. It'll be a bit weird to have it as a bitmask,
but feels like returning just a single enum pipe could make
things more complicated. So yeah, 'u8 *primary_pipe' seems perhaps the
best compromise.

-- 
Ville Syrjälä
Intel