（僅作記錄）

1. 平臺：rk3588

2. sensor：imx415

3. 配置所需文件：

IMX415_AppNote_DOL_E_Rev1.0

IMX415-AAQR-C_TechnicalDatasheet_E_Rev0.4

HDR功能，其曝光增益和線性模式不一樣，有各種的計算公式以及邏輯條件限制，具體看datasheet里面的restriction。

以HDR2為例，首先看下datasheet里的 restriction 如下圖所示；

?

?上面那兩張圖就是配置hdrae所需要的，此外可以先理解一下RHS1 SHR0 SHR1，看下圖

?可以如下簡單理解：

FSC = vts?

SHR0= FSC - l_exp_time ；

RHS1= s_exp_time + SHR1 ；

接下來看下代碼，根據(jù)圖中的限制條件，一一列出；其實也挺簡單的。

/* Restrictions* FSC = 2 * VMAX and FSC should be 4n;* exp_l = FSC - SHR0 + Toffset;* exp_l should be even value;** SHR0 = FSC - exp_l + Toffset;* SHR0 <= (FSC -8);* SHR0 >= RHS1 + 9;* SHR0 should be 2n;** exp_s = RHS1 - SHR1 + Toffset;* exp_s should be even value;** RHS1 < BRL * 2;* RHS1 <= SHR0 - 9;* RHS1 >= SHR1 + 8;* SHR1 >= 9;* RHS1(n+1) >= RHS1(n) + BRL * 2 -FSC + 2;** SHR1 should be 2n+1 and RHS1 should be 4n+1;*//* The HDR mode vts is double by default to workaround T-line */ fsc = imx415->cur_vts;shr0 = fsc - l_exp_time;if (imx415->cur_mode->height == 2192) {rhs1_max = min(RHS1_MAX_X2(BRL_ALL), ((shr0 - 9u) / 4 * 4 + 1));rhs1_min = max(SHR1_MIN_X2 + 8u, rhs1_old + 2 * BRL_ALL - fsc + 2);} else {rhs1_max = min(RHS1_MAX_X2(BRL_BINNING), ((shr0 - 9u) / 4 * 4 + 1));rhs1_min = max(SHR1_MIN_X2 + 8u, rhs1_old + 2 * BRL_BINNING - fsc + 2);}rhs1_min = (rhs1_min + 3) / 4 * 4 + 1;rhs1 = (SHR1_MIN_X2 + s_exp_time + 3) / 4 * 4 + 1;/* shall be 4n + 1 */dev_dbg(&client->dev,"line(%d) rhs1 %d, rhs1 min %d rhs1 max %d\n",__LINE__, rhs1, rhs1_min, rhs1_max);if (rhs1_max < rhs1_min) {dev_err(&client->dev,"The total exposure limit makes rhs1 max is %d,but old rhs1 limit makes rhs1 min is %d\n",rhs1_max, rhs1_min);return -EINVAL;}rhs1 = clamp(rhs1, rhs1_min, rhs1_max);dev_dbg(&client->dev,"line(%d) rhs1 %d, short time %d rhs1_old %d, rhs1_new %d\n",__LINE__, rhs1, s_exp_time, rhs1_old, rhs1);rhs1_old = rhs1;if (rhs1 - s_exp_time <= SHR1_MIN_X2) {shr1 = SHR1_MIN_X2;s_exp_time = rhs1 - shr1;} else {shr1 = rhs1 - s_exp_time;}if (shr0 < rhs1 + 9)shr0 = rhs1 + 9;else if (shr0 > fsc - 8)shr0 = fsc - 8; 注釋： rhs1_min = (rhs1_min + 3) / 4 * 4 + 1; rhs1 = (SHR1_MIN_X2 + s_exp_time + 3) / 4 * 4 + 1;/* shall be 4n + 1 */ 像rhs1_min + 3主要是4對齊，建議往大的對齊，例如 （11+3）/4*4+1=12+1; 11/4*4+1=8+1; 所以11當然是往大的12對齊而不是8.

提一下線性模式的曝光配置，不同sensor，寫法不一樣的；有的sensor是直接通過shr0來設(shè)置曝光的（shr寄存器）；有的直接像曝光寄存器寫入曝光值。如下分別用imx335和imx378為例

case V4L2_CID_EXPOSURE:/* 4 least significant bits of expsoure are fractional part */ret = imx577_write_reg(imx577->client,IMX577_REG_EXPOSURE,IMX577_REG_VALUE_16BIT,ctrl->val);break; case V4L2_CID_EXPOSURE:if (imx335->cur_mode->hdr_mode != NO_HDR)return ret;shr0 = imx335->cur_vts - ctrl->val;ret = imx335_write_reg(imx335->client, IMX335_LF_EXPO_REG_L,IMX335_REG_VALUE_08BIT,IMX335_FETCH_EXP_L(shr0));ret |= imx335_write_reg(imx335->client, IMX335_LF_EXPO_REG_M,IMX335_REG_VALUE_08BIT,IMX335_FETCH_EXP_M(shr0));ret |= imx335_write_reg(imx335->client, IMX335_LF_EXPO_REG_H,IMX335_REG_VALUE_08BIT,IMX335_FETCH_EXP_H(shr0));dev_dbg(&client->dev, "set exposure(shr0) %d = cur_vts(%d) - val(%d)\n",shr0, imx335->cur_vts, ctrl->val);break;

以上需要自己去體會哈！

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