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<div class=" wh_topic_content body "><main role="main"><article class="- topic/topic concept/concept topic concept" role="article" aria-labelledby="ariaid-title1">
<span class="edit-link" style="font-size:12px; opacity:0.6; text-align:right; vertical-align:middle"><a target="_blank" title="Edit this document" href="http://172.16.35.88/tasks/jdssno1uvvbf2mltu9kb9v3if05d5gopuakboe8hlud18rma/edit/F:/aicdita/aicdita-cn/topics/sdk/uart/uart_faq.dita">Edit online</a></span><h1 class="- topic/title title topictitle1" id="ariaid-title1">常见问题</h1>
<div class="date inPage">15 Jan 2024</div><div style="color: gray;">
Read time: 2 minute(s)
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<div class="- topic/body concept/conbody body conbody">
<section class="- topic/section section" id="uart_common_issues__section_qzk_wcz_21c" data-ofbid="uart_common_issues__section_qzk_wcz_21c"><h2 class="- topic/title title sectiontitle">端口非 tty 设备</h2>
<p class="- topic/p p" data-ofbid="d117383e38__20250123155210"><strong class="+ topic/ph hi-d/b ph b">现象</strong></p>
<div class="- topic/p p" data-ofbid="d117383e42__20250123155210">
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__codeblock_lr4_ycz_21c" data-ofbid="uart_common_issues__codeblock_lr4_ycz_21c"><code>test_uart -N /dev/ttyS1 /detv/ttySw2 <span class="hl-number">1145200</span></code></pre>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__codeblock_q2p_dds_5dc" data-ofbid="uart_common_issues__codeblock_q2p_dds_5dc"><code>[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] Test Mode: <span class="hl-number">0</span>:Normal Test
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] Send Device : /dev/ttyS1
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] Receive Device : /dev/ttyS2
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] m_Baudrate : <span class="hl-number">115200</span>
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] standard input is not a terminal device <strong class="hl-keyword">for</strong> /dev/ttyS1
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] tcgetattr: Bad file descriptor
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] standard input is not a terminal device <strong class="hl-keyword">for</strong> /dev/ttyS2
[<span class="hl-number">2022</span>-<span class="hl-number">01</span>-<span class="hl-number">26</span> <span class="hl-number">16</span>:<span class="hl-number">23</span>:<span class="hl-number">43</span>] tcgetattr: Bad file descriptor
</code></pre>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__codeblock_rtt_dds_5dc" data-ofbid="uart_common_issues__codeblock_rtt_dds_5dc"><code>echo <span class="hl-number">111</span> &gt; /dev/ttyS1</code></pre>
<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__codeblock_wl1_2ds_5dc" data-ofbid="uart_common_issues__codeblock_wl1_2ds_5dc"><code>write error: Input/output error</code></pre>
</div>
<p class="- topic/p p" data-ofbid="d117383e57__20250123155210"><strong class="+ topic/ph hi-d/b ph b">原因分析</strong></p>
<div class="- topic/p p" data-ofbid="d117383e61__20250123155210">原因新版 IC 系统修改了 UART Clk 的地址dts
中未同步修改,导致设备虽然进行了初始化,但模块无数据读写:<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__pre_rzk_wcz_21c" data-ofbid="uart_common_issues__pre_rzk_wcz_21c"><code>devmem <span class="hl-number">0x18711000</span> <span class="hl-number">32</span></code></pre></div>
<div class="- topic/p p" data-ofbid="d117383e67__20250123155210">UART 的所有寄存器读不到数据clk
未工作:<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__codeblock_jrl_2ds_5dc" data-ofbid="uart_common_issues__codeblock_jrl_2ds_5dc"><code>[<span class="hl-number">2022</span>-<span class="hl-number">02</span>-<span class="hl-number">07</span> <span class="hl-number">09</span>:<span class="hl-number">23</span>:<span class="hl-number">06</span>] <span class="hl-number">0x00000000</span></code></pre></div>
</section>
<section class="- topic/section section" id="uart_common_issues__section_szk_wcz_21c" data-ofbid="uart_common_issues__section_szk_wcz_21c"><h2 class="- topic/title title sectiontitle">长包卡死</h2>
<p class="- topic/p p" data-ofbid="d117383e78__20250123155210"><strong class="+ topic/ph hi-d/b ph b">现象</strong></p>
<p class="- topic/p p" data-ofbid="d117383e82__20250123155210">发送 128 字节以内的短包,模块可正常收发,发送超过 128 字节的长包,会卡死</p>
<p class="- topic/p p" data-ofbid="d117383e85__20250123155210"><strong class="+ topic/ph hi-d/b ph b">原因分析</strong></p>
<div class="- topic/p p" data-ofbid="d117383e89__20250123155210">D211 RX DMA 要求严格设置 DMA RX size如果该 size 设置不对,则会有如下问题:<ul class="- topic/ul ul" id="uart_common_issues__ul_uzk_wcz_21c" data-ofbid="uart_common_issues__ul_uzk_wcz_21c">
<li class="- topic/li li" data-ofbid="d117383e93__20250123155210">
<p class="- topic/p p" data-ofbid="d117383e95__20250123155210">如果 fifo 中有数据 150而设置 rx size 为 120则丢失 30 数据</p>
</li>
<li class="- topic/li li" data-ofbid="d117383e99__20250123155210">
<p class="- topic/p p" data-ofbid="d117383e101__20250123155210">如果 fifo 中有数据 150而设置 rx size 为 160 则永远无法填充满,则永远收不回数据,卡死</p>
<p class="- topic/p p" data-ofbid="d117383e104__20250123155210">目前默认的 8250 驱动中,设置的 rx size 为 1000但 fifo 的大小只有
256因此永远无法填充完成故导致系统卡死。</p>
</li>
</ul></div>
</section>
<section class="- topic/section section" id="uart_common_issues__section_vzk_wcz_21c" data-ofbid="uart_common_issues__section_vzk_wcz_21c"><h2 class="- topic/title title sectiontitle">初始化乱码现象</h2>
<p class="- topic/p p" data-ofbid="d117383e115__20250123155210"><strong class="+ topic/ph hi-d/b ph b">现象</strong></p>
<p class="- topic/p p" data-ofbid="d117383e119__20250123155210">reboot 测试中发现 Linux 初始化 UART 时输出乱码 0xFF导致接收端 Python 脚本 断开</p>
<p class="- topic/p p" data-ofbid="d117383e122__20250123155210"><strong class="+ topic/ph hi-d/b ph b">原因分析</strong></p>
<p class="- topic/p p" data-ofbid="d117383e126__20250123155210">8250 驱动因为要兼容很多 IC因此初始化时有一个自动 try 的机制autoconfig通过对硬件模块的测试来确认 IP 类型和特殊功能,此自动 try
工作会频繁操作寄存器,既可能造成不确定的影响(输出上述乱码),也会增加系统开销,而我们 UART 模块特性固定,可以预先进行配置,不进行 try。</p>
<div class="- topic/p p" data-ofbid="d117383e130__20250123155210">autoconfig 的核心是设置了 port-&gt;type 为 PORT_16550A我们直接设置 type 后即可不使用 autoconfig 流程。关闭
autoconfig
的流程为:<pre class="+ topic/pre pr-d/codeblock pre codeblock language-c" id="uart_common_issues__pre_xzk_wcz_21c" data-ofbid="uart_common_issues__pre_xzk_wcz_21c"><code>aic8250_probe:
p-&gt;type = PORT_<span class="hl-number">16550</span>A;
p-&gt;flags = UPF_FIXED_TYPE;
uart_configure_port:
<strong class="hl-keyword">if</strong> (!(port-&gt;flags &amp; UPF_FIXED_TYPE)) {
port-&gt;type = PORT_UNKNOWN;
flags |= UART_CONFIG_TYPE;
}
serial8250_config_port:
<strong class="hl-keyword">if</strong> (flags &amp; UART_CONFIG_TYPE)
autoconfig(up);</code></pre></div>
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<div class=" wh_topic_toc "><div class="wh_topic_label">在本页上</div><ul><li class="section-item"><div class="section-title"><a href="#uart_common_issues__section_qzk_wcz_21c" data-tocid="uart_common_issues__section_qzk_wcz_21c">端口非 tty 设备</a></div></li><li class="section-item"><div class="section-title"><a href="#uart_common_issues__section_szk_wcz_21c" data-tocid="uart_common_issues__section_szk_wcz_21c">长包卡死</a></div></li><li class="section-item"><div class="section-title"><a href="#uart_common_issues__section_vzk_wcz_21c" data-tocid="uart_common_issues__section_vzk_wcz_21c">初始化乱码现象</a></div></li></ul></div>
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