drm/amd/display: fix handling of max_downscale_src_width fail check in SPL

[Why]
If max_downscale_src_width check fails, we exit early from
spl_calculate_scaler_params but dscl_prog_data is not fully
populated. If viewport is left at 0, it can cause crash in dml.

[How]
Call spl_set_dscl_prog_data before we exit early from
spl_calculate_scaler_params to populate dscl_prog_data
Populate taps in spl_get_optimal_number_of_taps

Reviewed-by: Alvin Lee <[e-mail]>
Signed-off-by: Samson Tam <[e-mail]>
Signed-off-by: Tom Chung <[e-mail]>
Tested-by: Daniel Wheeler <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dc/spl/dc_spl.c

···
 
 	if (spl_scratch->scl_data.viewport.width > spl_scratch->scl_data.h_active &&
 		max_downscale_src_width != 0 &&
-		spl_scratch->scl_data.viewport.width > max_downscale_src_width)
+		spl_scratch->scl_data.viewport.width > max_downscale_src_width) {
+		memcpy(&spl_scratch->scl_data.taps, in_taps, sizeof(struct spl_taps));
+		*enable_easf_v = false;
+		*enable_easf_h = false;
+		*enable_isharp = false;
 		return false;
+	}
 
 	/* Disable adaptive scaler and sharpener when integer scaling is enabled */
 	if (spl_in->scaling_quality.integer_scaling) {
···
 	// Clamp
 	spl_clamp_viewport(&spl_scratch.scl_data.viewport);
 
-	if (!res)
-		return res;
-
 	// Save all calculated parameters in dscl_prog_data structure to program hw registers
 	spl_set_dscl_prog_data(spl_in, &spl_scratch, spl_out, enable_easf_v, enable_easf_h, enable_isharp);
+
+	if (!res)
+		return res;
 
 	if (spl_in->lls_pref == LLS_PREF_YES) {
 		if (spl_in->is_hdr_on)