Re: [Intel-gfx] [PATCH v6 6/9] drm/i915/vdsc: Check slice design requirement

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 11 Jan 2023, "Kandpal, Suraj" <suraj.kandpal@intel.com> wrote:
>> 
>> On Wed, 11 Jan 2023, Suraj Kandpal <suraj.kandpal@intel.com> wrote:
>> > Add function to check if slice design requirements are being met as
>> > defined in the below link section Slice Design Requirement
>> >
>> > https://gfxspecs.intel.com/Predator/Home/Index/49259
>> >
>> 
>> Just add this:
>> 
>> Bspec: 49259
>> 
>> and no URLs.
>> 
>
> Ohkay got it
>
>> > Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
>> > ---
>> >  drivers/gpu/drm/i915/display/intel_vdsc.c | 32
>> > +++++++++++++++++++++++
>> >  1 file changed, 32 insertions(+)
>> >
>> > diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > index 52a82d8b289e..0a683d6dff33 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> > @@ -447,6 +447,29 @@ calculate_rc_params(struct rc_parameters *rc,
>> >  	}
>> >  }
>> >
>> > +static int intel_dsc_check_slice_design_req(struct intel_crtc_state *pipe_config,
>> > +					    struct drm_dsc_config *vdsc_cfg)
>> 
>> Bikeshedding, I think "check" is generally a poor verb in a function name.
>> 
>> intel_dsc_slice_dimensions_valid() or something like that?
>
> Sure then ill go with intel_dsc_validate_slice_design

I'm often considering function names from the caller perspective. Say it
out loud, wonder what it sounds like the function is doing, and what it
returns.

intel_dsc_slice_dimensions_valid() is a predicate function that returns
true or false. Either the slice dimensions are valid or not.

Also, "slice design" is incomprehensible to anyone who hasn't read the
bspec. I had to look it up before I understood what this was about. And
it's just the dimensions that are being checked.


BR,
Jani.


>
> Regards,
> Suraj Kandpal
>> 
>> 
>> > +{
>> > +	if (pipe_config->output_format == INTEL_OUTPUT_FORMAT_RGB ||
>> > +	    pipe_config->output_format == INTEL_OUTPUT_FORMAT_YCBCR444) {
>> > +		if (vdsc_cfg->slice_height > 4095)
>> > +			return -EINVAL;
>> > +		if (vdsc_cfg->slice_height * vdsc_cfg->slice_width < 15000)
>> > +			return -EINVAL;
>> > +	} else if (pipe_config->output_format ==
>> INTEL_OUTPUT_FORMAT_YCBCR420) {
>> > +		if (!(vdsc_cfg->slice_width % 2))
>> > +			return -EINVAL;
>> > +		if (!(vdsc_cfg->slice_height % 2))
>> > +			return -EINVAL;
>> > +		if (vdsc_cfg->slice_height > 4094)
>> > +			return -EINVAL;
>> > +		if (vdsc_cfg->slice_height * vdsc_cfg->slice_width < 30000)
>> > +			return -EINVAL;
>> > +	}
>> > +
>> > +	return 0;
>> > +}
>> > +
>> >  int intel_dsc_compute_params(struct intel_crtc_state *pipe_config)  {
>> >  	struct intel_crtc *crtc = to_intel_crtc(pipe_config->uapi.crtc);
>> > @@ -455,11 +478,20 @@ int intel_dsc_compute_params(struct intel_crtc_state
>> *pipe_config)
>> >  	u16 compressed_bpp = pipe_config->dsc.compressed_bpp;
>> >  	const struct rc_parameters *rc_params;
>> >  	struct rc_parameters *rc = NULL;
>> > +	int err;
>> >  	u8 i = 0;
>> >
>> >  	vdsc_cfg->pic_width = pipe_config->hw.adjusted_mode.crtc_hdisplay;
>> >  	vdsc_cfg->slice_width = DIV_ROUND_UP(vdsc_cfg->pic_width,
>> >  					     pipe_config->dsc.slice_count);
>> > +
>> > +	err = intel_dsc_check_slice_design_req(pipe_config, vdsc_cfg);
>> > +
>> > +	if (err) {
>> > +		drm_dbg_kms(&dev_priv->drm, "Slice design requirements not
>> met\n");
>> > +		return err;
>> > +	}
>> > +
>> >  	/*
>> >  	 * According to DSC 1.2 specs if colorspace is YCbCr then convert_rgb is 0
>> >  	 * else 1
>> 
>> --
>> Jani Nikula, Intel Open Source Graphics Center

-- 
Jani Nikula, Intel Open Source Graphics Center