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

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Message-ID: <2eab42cde34723a195e7a0287db08b25f8388a3b.camel@codeconstruct.com.au>
Date:   Tue, 12 Dec 2023 09:33:17 +1030
From:   Andrew Jeffery <andrew@...econstruct.com.au>
To:     Quan Nguyen <quan@...amperecomputing.com>,
        Brendan Higgins <brendan.higgins@...ux.dev>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Joel Stanley <joel@....id.au>,
        Andi Shyti <andi.shyti@...nel.org>,
        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
Cc:     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

On Mon, 2023-12-11 at 17:22 +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: Andrew Jeffery <andrew@...econstruct.com.au>

Thanks Quan!