drm/msm/dpu: Prevent unnecessary hardware block migration

[chenchongbiao]

When one CRTC is disabled during Type-C hot-unplug, the DPU Resource Manager would unnecessarily reassign hardware blocks (CTL, LM, DSPP) for the remaining active CRTC. The sequence:

1. crtc-0's dpu_rm_release() frees ctl-0, LM-0/1
2. crtc-1's dpu_crtc_assign_resources() releases ctl-1/LM-2/3 then calls dpu_rm_reserve()
3. _dpu_rm_reserve_ctls() scans from j=0, finds ctl-0 free, assigns it to crtc-1 instead of keeping ctl-1
4. _dpu_rm_reserve_lms() does the same for LM blocks
5. The hardware pipeline migration triggers a modeset that disables/re-enables the encoder, but vblank IRQ callbacks are not properly re-registered (cb:0x0 in core_irq debugfs)
6. INTF hardware continues generating vsync but interrupts go unhandled, causing the display to freeze

Fix by:

• In dpu_crtc_assign_resources(): only release resources when the CRTC is being disabled, not on every modeset. For enabled CRTCs, let dpu_rm_reserve() retain the existing assignment.
• In _dpu_rm_reserve_ctls() and _dpu_rm_reserve_lms(): use a two-pass approach that first prefers hardware blocks already assigned to this CRTC, then falls back to the free pool.

[chenchongbiao]

改动一：dpu_crtc_assign_resources
// 改前：
dpu_rm_release(global_state, crtc); // 无条件释放
if (!crtc_state->enable)
return 0;
dpu_rm_reserve(...); // 重新分配

// 改后：
if (!crtc_state->enable) {
dpu_rm_release(global_state, crtc); // 只在关闭时释放
return 0;
}
dpu_rm_reserve(...); // 开着就不释放，直接 reserve

原来无论 CRTC 开还是关，先扔干净再重新捡。释放 ctl-0 后 ctl-0 变成空闲，然后 crtc-1 的 reserve 从 j=0 扫描就会抢走。
改后：CRTC 还开着就不扔。reserve 时 ctl_to_crtc_id[1] 还指着 crtc-1，第一轮"已经是我自己的"直接命中，不动。
改动二：_dpu_rm_reserve_ctls — CTL 分配

// 改前：一轮循环
for (j = 0; j < N; j++) {
if (reserved_by_other(...)) continue; // 跳过被占的
ctl_idx[i] = j; // 第一个空闲就分
break;
}

// 改后：两轮循环
// 第一轮：只找"我已经占着的"
for (j = 0; j < N; j++) {
if (ctl_to_crtc_id[j] != crtc_id) continue; // 不是我占的跳过
ctl_idx[i] = j; // 保留
i++;
}
// 第二轮：不够再从空闲池找
for (j = 0; j < N; j++) {
if (reserved_by_other(...)) continue;
ctl_idx[i] = j;
i++;
}
第一轮只看 ctl_to_crtc_id[j] == crtc_id——"这个 CTL 登记在我名下"，直接拿。第二轮才从真正空闲的池子里找。

改动三：_dpu_rm_reserve_lms — LM 分配，同理但加了一个关键点
// 第一轮找已有的 LM，但跳过 dpu_rm_check_lm_and_get_connected_blks
// 因为：
// - boot 时 topology 可能 num_dspp=0，检查放行
// - hotplug 后 topology 变了，num_dspp>0，检查拒绝 LM-4/5（DSPP-1）
// - 既然之前能工作，就别重检，原样保留
// 直接从 LM 的硬件配置读 PP/DSPP 编号
pp_idx = lm_cfg->pingpong - PINGPONG_0;
if (topology->num_dspp) {
d = lm_cfg->dspp - DSPP_0;
dspp_idx = (d >= 0) ? d : 0; // -1 安全处理
}
不加的话 LM-4/5 被拒，退到第二轮抢走刚释放的 LM-2/3，HDMI 蓝屏。