linux-kernel - Re: [PATCH 16/33] serial: 8250: extract serial8250

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Message-ID: <d10b7892-bb4b-43ba-9804-7a03351927ec@kernel.org>
Date: Mon, 23 Jun 2025 08:59:50 +0200
From: Jiri Slaby <jirislaby@...nel.org>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 linux-serial <linux-serial@...r.kernel.org>,
 LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 16/33] serial: 8250: extract serial8250_initialize()

On 11. 06. 25, 14:19, Ilpo Järvinen wrote:
>> +	 * variable. So, let's just don't test if we receive TX irq.  This way, we'll never enable
>> +	 * UART_BUG_TXEN.
>> +	 */
>> +	if (!(port->quirks & UPQ_NO_TXEN_TEST)) {
>> +		/* Do a quick test to see if we receive an interrupt when we enable the TX irq. */
>> +		serial_port_out(port, UART_IER, UART_IER_THRI);
>> +		lsr_TEMT = serial_port_in(port, UART_LSR) & UART_LSR_TEMT;
>> +		iir_NOINT = serial_port_in(port, UART_IIR) & UART_IIR_NO_INT;
>> +		serial_port_out(port, UART_IER, 0);
>> +
>> +		if (lsr_TEMT && iir_NOINT) {
>> +			if (!(up->bugs & UART_BUG_TXEN)) {
>> +				up->bugs |= UART_BUG_TXEN;
>> +				dev_dbg(port->dev, "enabling bad tx status workarounds\n");
>> +			}
>> +		} else {
>> +			up->bugs &= ~UART_BUG_TXEN;
> 
> Is this necessary at all as the line above is the only place setting this
> flag (AFAICT)?

TBH, I don't know. I guess it is unnecessary but it is there since this 
UART_BUG_TXEN was added. /me shrugs.

thanks,
-- 
js
suse labs