linux-kernel - Re: [PATCH v4 2/2] i2c: aspeed: Acknowledge Tx done with and without ACK irq late

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Message-ID: <20231215014505.he6ozzxd5jnjgvol@zenone.zhora.eu>
Date: Fri, 15 Dec 2023 02:45:05 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Quan Nguyen <quan@...amperecomputing.com>
Cc: Brendan Higgins <brendan.higgins@...ux.dev>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Joel Stanley <joel@....id.au>,
	Andrew Jeffery <andrew@...econstruct.com.au>,
	Wolfram Sang <wsa@...nel.org>,
	Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>,
	Guenter Roeck <linux@...ck-us.net>, linux-i2c@...r.kernel.org,
	openbmc@...ts.ozlabs.org, linux-arm-kernel@...ts.infradead.org,
	linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Cosmo Chou <chou.cosmo@...il.com>,
	Open Source Submission <patches@...erecomputing.com>,
	Phong Vo <phong@...amperecomputing.com>,
	"Thang Q . Nguyen" <thang@...amperecomputing.com>
Subject: Re: [PATCH v4 2/2] i2c: aspeed: Acknowledge Tx done with and without
 ACK irq late

Hi Quan,

On Mon, Dec 11, 2023 at 05:22:17PM +0700, Quan Nguyen wrote:
> Commit 2be6b47211e1 ("i2c: aspeed: Acknowledge most interrupts early in
> interrupt handler") acknowledges most interrupts early before the slave
> irq handler is executed, except for the "Receive Done Interrupt status"
> which is acknowledged late in the interrupt.
> However, it has been observed that the early acknowledgment of "Transmit
> Done Interrupt Status" (with ACK or NACK) often causes the interrupt to
> be raised in READ REQUEST state, that shows the
> "Unexpected ACK on read request." complaint messages.
> 
> Assuming that the "Transmit Done" interrupt should only be acknowledged
> once it is truly processed, this commit fixes that issue by acknowledging
> interrupts for both ACK and NACK cases late in the interrupt handler.
> 
> Fixes: 2be6b47211e1 ("i2c: aspeed: Acknowledge most interrupts early in interrupt handler")
> Signed-off-by: Quan Nguyen <quan@...amperecomputing.com>

Reviewed-by: Andi Shyti <andi.shyti@...nel.org>

Thanks,
Andi