Messages in this thread | | | Date | Mon, 23 Jan 2006 22:39:43 +0900 (JST) | Subject | Re: [PATCH] serial: serial_txx9 driver update | From | Atsushi Nemoto <> |
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>>>>> On Mon, 23 Jan 2006 09:57:00 +0000, Russell King <rmk+lkml@arm.linux.org.uk> said: >> - if (disr & TXX9_SIDISR_UOER) >> + if (disr & TXX9_SIDISR_UOER) { >> up-> port.icount.overrun++; >> + /* >> + * The receiver read buffer still hold >> + * a char which caused overrun. >> + * Ignore next char by adding RFDN_MASK >> + * to ignore_status_mask temporarily. >> + */ >> + next_ignore_status_mask |= >> + TXX9_SIDISR_RFDN_MASK; >> + }
rmk> I'm not sure what you mean here.
rmk> If we successfully received the string ABCDEFGH, and the next character rmk> to be received (I) causes an overrun condition, what happens in the rmk> case that overruns are not ignored?
In this case, I will read ABCDEFG without errors, and then I with an overrun
rmk> Will you read ABCDEFG without any errors from the UART, and then H with rmk> an overrun error? If so, you should pass to the TTY layer ABCDEFGH and rmk> then a NUL character with TTY_OVERRUN set. Note that uart_insert_char() rmk> does this for you.
Yes, in this case I will read ABCDEFG without error, and then H with an overrun error. But the UART still hold "I" in its "read buffer". The "read buffer" is exist outside the receiver FIFO. So if 'J' comes in later, I will read "IJ". There is no way to clear the "read buffer" except resetting the UART.
Resetting the whole UART is too intrusive, so I chose a way in the patch (Ignore just next one char after an overrun error.)
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