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Date: Fri, 15 Dec 2023 02:45:05 +0100
From: Andi Shyti <andi.shyti@kernel.org>
To: Quan Nguyen <quan@os.amperecomputing.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Joel Stanley <joel@jms.id.au>,
	Andrew Jeffery <andrew@codeconstruct.com.au>,
	Wolfram Sang <wsa@kernel.org>,
	Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>,
	Guenter Roeck <linux@roeck-us.net>, linux-i2c@vger.kernel.org,
	openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org,
	linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	Cosmo Chou <chou.cosmo@gmail.com>,
	Open Source Submission <patches@amperecomputing.com>,
	Phong Vo <phong@os.amperecomputing.com>,
	"Thang Q . Nguyen" <thang@os.amperecomputing.com>
Subject: Re: [PATCH v4 2/2] i2c: aspeed: Acknowledge Tx done with and without
 ACK irq late
Message-ID: <20231215014505.he6ozzxd5jnjgvol@zenone.zhora.eu>
References: <20231211102217.2436294-1-quan@os.amperecomputing.com>
 <20231211102217.2436294-3-quan@os.amperecomputing.com>
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In-Reply-To: <20231211102217.2436294-3-quan@os.amperecomputing.com>

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@os.amperecomputing.com>

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

Thanks,
Andi