Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Received-SPF: Pass (protection.outlook.com: domain of cern.ch designates
 188.184.36.46 as permitted sender) receiver=protection.outlook.com;
 client-ip=188.184.36.46; helo=cernmxgwlb4.cern.ch;
From:   Federico Vaga <federico.vaga@cern.ch>
To:     Peter Korsgaard <peter@korsgaard.com>, Andrew Lunn <andrew@lunn.ch>
CC:     Peter Rosin <peda@axentia.se>, <linux-i2c@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>,
        Federico Vaga <federico.vaga@cern.ch>
Subject: [PATCH v7 2/5] i2c: ocores: do not handle IRQ if IF is not set
Date:   Thu, 14 Feb 2019 09:51:31 +0100
Message-ID: <20190214085134.12900-3-federico.vaga@cern.ch>
In-Reply-To: <20190214085134.12900-1-federico.vaga@cern.ch>
References: <20190214085134.12900-1-federico.vaga@cern.ch>
MIME-Version: 1.0
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Feb 2019 08:51:46.4296
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 9fe71177-fe65-45fa-2a1d-08d69259a6c7
X-MS-Exchange-CrossTenant-Id: c80d3499-4a40-4a8c-986e-abce017d6b19
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=c80d3499-4a40-4a8c-986e-abce017d6b19;Ip=[188.184.36.46];Helo=[cernmxgwlb4.cern.ch]
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM4PR0601MB2145
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

If the Interrupt Flag (IF) is not set, we should not handle the IRQ:
- the line can be shared with other devices
- it can be a spurious interrupt

To avoid reading twice the status register, the ocores_process() function
expects it to be read by the caller.

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
---
 drivers/i2c/busses/i2c-ocores.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index aa85202..fcc2558 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -143,10 +143,9 @@ static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
 	return i2c->getreg(i2c, reg);
 }
 
-static void ocores_process(struct ocores_i2c *i2c)
+static void ocores_process(struct ocores_i2c *i2c, u8 stat)
 {
 	struct i2c_msg *msg = i2c->msg;
-	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
 	unsigned long flags;
 
 	/*
@@ -223,8 +222,12 @@ out:
 static irqreturn_t ocores_isr(int irq, void *dev_id)
 {
 	struct ocores_i2c *i2c = dev_id;
+	u8 stat = oc_getreg(i2c, OCI2C_STATUS);
+
+	if (!(stat & OCI2C_STAT_IF))
+		return IRQ_NONE;
 
-	ocores_process(i2c);
+	ocores_process(i2c, stat);
 
 	return IRQ_HANDLED;
 }
-- 
2.15.0