Re: [Intel-gfx] [PATCH v3 01/11] drm/i915: Add a table with a descriptor for all i915 modifiers

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

On Fri, Oct 15, 2021 at 01:09:11AM +0300, Imre Deak wrote:
> +static const struct intel_modifier_desc intel_modifiers[] = {
> +	{
> +		.modifier = DRM_FORMAT_MOD_LINEAR,
> +		.display_ver = DISPLAY_VER_ALL,
> +
> +		.is_linear = true,
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_X_TILED,
> +		.display_ver = DISPLAY_VER_ALL,
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Y_TILED,
> +		.display_ver = { 9, 13 },
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Yf_TILED,
> +		.display_ver = { 9, 11 },
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Y_TILED_CCS,
> +		.display_ver = { 9, 11 },
> +
> +		.ccs.type = INTEL_CCS_RC,
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Yf_TILED_CCS,
> +		.display_ver = { 9, 11 },
> +
> +		.ccs.type = INTEL_CCS_RC,
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS,
> +		.display_ver = { 12, 13 },
> +
> +		.ccs.type = INTEL_CCS_RC,
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS_CC,
> +		.display_ver = { 12, 13 },
> +
> +		.ccs.type = INTEL_CCS_RC_CC,
> +	},
> +	{
> +		.modifier = I915_FORMAT_MOD_Y_TILED_GEN12_MC_CCS,
> +		.display_ver = { 12, 13 },
> +
> +		.ccs.type = INTEL_CCS_MC,
> +	},
> +};
> +
<snip>
> +u64 *intel_fb_plane_get_modifiers(struct drm_i915_private *i915,
> +				  enum intel_plane_caps plane_caps)
> +{
> +	u64 *list, *p;
> +	int count = 1;		/* +1 for invalid modifier terminator */
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(intel_modifiers); i++) {
> +		if (plane_has_modifier(i915, plane_caps, &intel_modifiers[i]))
> +			count++;
> +	}
> +
> +	list = kmalloc_array(count, sizeof(*list), GFP_KERNEL);
> +	if (drm_WARN_ON(&i915->drm, !list))
> +		return NULL;
> +
> +	p = list;
> +	for (i = 0; i < ARRAY_SIZE(intel_modifiers); i++) {
> +		if (plane_has_modifier(i915, plane_caps, &intel_modifiers[i]))
> +			*p++ = intel_modifiers[i].modifier;
> +	}
> +	*p++ = DRM_FORMAT_MOD_INVALID;

Oh, one thing I just realized is that this will now list the modifiers
in the opposite order to what we had before. Previously we had roughly
compressed->tiled->linear order. I'm not sure sure anything relies on
that, but seems best to try and preserve it. I guess one could think
of it as some kind of priority order for the modifiers, where the more
efficient ones (in some sense) come first.

-- 
Ville Syrjälä
Intel