SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The functional aspect of the write-back pipeline scaler unit is identical to the video pipeline scaler unit (see Section 11.2.4.10.4, DISPC Scaler Unit), except in the output width when scaling ARGB components. The resulting output format is ARGB32 instead of ARGB40.In addition, the scaling limitations described in Section 11.2.4.10.4.2 are relevant only to the video pipelines scaler units. In write-back memory-to-memory mode there are no limitations on the F_CLK/DSS_DISPC_LCDn_PCLK ratio for horizontal resampling.
The programmable coefficients of the polyphase filters are signed 8-bit values (except for the central coefficient, which is unsigned). The write-back scaler component has an 8-bit input and an 8-bit output.
Figure 11-69 and Figure 11-70 show the scaler macro-architecture for the component A, R, G, B, and Y. Figure 11-71 and Figure 11-72 show the scaler macro-architecture for component Cr and Cb.
The scaling output can be clipped to an output range of [0:255] or [16:240] by configuring the DISPC_WB_ATTRIBUTES[11] FULLRANGE bit.
Table 11-78 and Table 11-79 list all the bit fields in the function to set each coefficient.
Taps | Coefficient | 3 Taps | 5 Taps | Registers |
---|---|---|---|---|
Bit Field | Bit Field | |||
Vertical | Cv(–2) | FIRVC22 | DISPC_WB_FIR_COEF_V_i | |
Cv(–1) | FIRVC2 | FIRVC2 | DISPC_WB_FIR_COEF_HV_i | |
Cv(0) | FIRVC1 | FIRVC1 | DISPC_WB_FIR_COEF_HV_i | |
Cv(1) | FIRVC0 | FIRVC0 | DISPC_WB_FIR_COEF_HV_i | |
Cv(2) | FIRVC00 | DISPC_WB_FIR_COEF_V_i | ||
Horizontal | Ch(–2) | FIRHC4 | DISPC_WB_FIR_COEF_HV_i | |
Ch(–1) | FIRHC3 | DISPC_WB_FIR_COEF_H_i | ||
Ch(0) | N/A | FIRHC2 | DISPC_WB_FIR_COEF_H_i | |
Ch(1) | FIRHC1 | DISPC_WB_FIR_COEF_H_i | ||
Ch(2) | FIRHC0 | DISPC_WB_FIR_COEF_H_i |
Taps | Coefficient | 3 Taps | 5 Taps | Registers |
---|---|---|---|---|
Bit Field | Bit Field | |||
Vertical | Cvc(–2) | FIRVC22 | DISPC_WB_FIR_COEF_V2_i | |
Cvc(–1) | FIRVC2 | FIRVC2 | DISPC_WB_FIR_COEF_HV2_i | |
Cvc(0) | FIRVC1 | FIRVC1 | DISPC_WB_FIR_COEF_HV2_i | |
Cvc(1) | FIRVC0 | FIRVC0 | DISPC_WB_FIR_COEF_HV2_i | |
Cvc(2) | FIRVC00 | DISPC_WB_FIR_COEF_V2_i | ||
Horizontal | Chc(–2) | FIRHC4 | DISPC_WB_FIR_COEF_HV2_i | |
Chc(–1) | FIRHC3 | DISPC_WB_FIR_COEF_H2_i | ||
Chc(0) | N/A | FIRHC2 | DISPC_WB_FIR_COEF_H2_i | |
Chc(1) | FIRHC1 | DISPC_WB_FIR_COEF_H2_i | ||
Chc(2) | FIRHC0 | DISPC_WB_FIR_COEF_H2_i |
The WB scaler unit vertical or/and horizontal sampling is defined by setting/resetting the DISPC_WB_ATTRIBUTES[6:5] RESIZEENABLE bit field.
A set of configuration must be valid before enabling the video up/downsampling block.
The following fields define the configuration of the video up/downsampling block for WB:
Table 11-80 lists the DISPC vertical and horizontal accumulator values and phases.
Accumulator Value | Phases f |
---|---|
0 | 0 |
128 or –896 | 1 |
256 or –768 | 2 |
384 or –640 | 3 |
512 or –512 | 4 |
640 or –384 | 5 |
768 or –256 | 6 |
896 or –128 | 7 |
Four YUV vertical up/downsampling coefficients are set in the DISPC_WB_FIR_COEF_HV2_i and DISPC_WB_FIR_COEF_V2_i registers. Table 11-78 and Table 11-79 summarize all coefficients and their respective registers.
Four YUV horizontal up/downsampling coefficients are set in the DISPC_WB_FIR_COEF_HV2_i and DISPC_WB_FIR_COEF_H2_i registers. Table 11-78 and Table 11-79 summarize all coefficients and their respective registers.