Re: Re: [PATCH v6 11/13] serial: 8250_dw: add Ambarella CV75 quirks

On Thu, 10 Sep 2026, Andy Shevchenko wrote:

On Thu, Sep 10, 2026 at 05:12:52PM +0800, zl020895 wrote:

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Wondering if we should undo this in the port's .shutdown() callback.

I saw the shutdown path already covers it: dw8250_shutdown() calls
serial8250_do_shutdown(), which does
	up->ier = 0;
	serial_port_out(port, UART_IER, 0);
so both the IER shadow and hardware IER are cleared, including ETOI.

Depending on the answer to Ilpo the enabling may need an updated comment
summarising the above.

I'd prefer removing the entire "Force them ..." sentence, it feels really 
basic detail about how ->ier works. I believe that would resolve your 
concern if relates to what shutdown does for the flag (clears it while 
the comment as is says nothing is supposed to clear it).

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At 2026-09-10 16:33:14, "Andy Shevchenko" [off-list ref] wrote:

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On Fri, Sep 04, 2026 at 02:38:18PM +0800, Long Zhao via B4 Relay wrote:

...

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+	/*
+	 * Ambarella keeps variant IER bits (e.g. ETOI) set for correct RX
+	 * timeout behaviour. Force them into the 8250 IER shadow so later
+	 * generic IER updates do not clear them.
+	 */

Wondering if we should undo this in the port's .shutdown() callback.

-- 
 i.