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<p class="MsoNormal">Hello All<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am debugging a UART issue on a Freescale PowerPC SOC.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My observations are:<o:p></o:p></p>
<p class="MsoListParagraph">When FiFo mode is enabled FCR[FEN]=1, and the Fifo size is 16byte. I see console prints not coming properly, lot of missing characters.<o:p></o:p></p>
<p class="MsoListParagraph">But here when I change the tx_loadsz to 8, the UART works fine.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> [PORT_16550A] = {<o:p></o:p></p>
<p class="MsoNormal"> .name = "16550A",<o:p></o:p></p>
<p class="MsoNormal"> .fifo_size = 16,<o:p></o:p></p>
<p class="MsoNormal">- .tx_loadsz = 16,<o:p></o:p></p>
<p class="MsoNormal">+ .tx_loadsz = 8,<o:p></o:p></p>
<p class="MsoNormal"> .fcr = UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,<o:p></o:p></p>
<p class="MsoNormal"> .flags = UART_CAP_FIFO,<o:p></o:p></p>
<p class="MsoNormal"> },<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Can anybody help to understand what is the significance of tx_loadsz. From the code (drivers/serial/tty/8250/8250.c), looks like this parameter controls the bytes we write to the UART Tx register at one time.<o:p></o:p></p>
<p class="MsoNormal">So ideally this should be equal to the Fifo size.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><i></i>I also see certain UARTs where tx_loadsz is not equal to fifo_size, less than fifo_size.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please help me to understand how should tx_loadsz be determined?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Many Thanks<o:p></o:p></p>
<p class="MsoNormal">Poonam <o:p></o:p></p>
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