vivado：mixed level sensitive and edge triggered event controls are not supported for synthesis

环境：vivado2018.2

如下主要部分代码里的always块报错：

[Synth 8-434] mixed level sensitive and edge triggered event controls are not supported for synthesis

always@(posedge clk or rst) begin
	...代码内容
end

stackoverflow上的解释大致为：
Mixed sensitive list of levels and edges is not synthesizable, because a flip-flop cannot be edge-tiggered and level-triggered at the same time. Check this link: Synthesis of always blocks
因为一个触发器不能同时是边缘触发和电平触发的，因此不可被综合

所以最好统一是边沿触发，或者直接去掉rst信号

always@(posedge clk or posedge rst) begin
	...代码内容
end