linux-kernel - [PATCH v2 04/10] gpio: stmpe: write int status register only when needed

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Message-ID: <1461845589-4826-5-git-send-email-patrice.chotard@st.com>
Date:	Thu, 28 Apr 2016 14:13:03 +0200
From:	<patrice.chotard@...com>
To:	<lee.jones@...aro.org>, <linus.walleij@...aro.org>,
	<gnurou@...il.com>, <linux-gpio@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC:	<linux-arm-kernel@...ts.infradead.org>, <maxime.coquelin@...com>,
	<amelie.delaunay@...com>, <shawnguo@...nel.org>,
	<kernel@...gutronix.de>, <dinguyen@...nsource.altera.com>,
	<vireshk@...nel.org>, <shiraz.linux.kernel@...il.com>,
	<thierry.reding@...il.com>, <gnurou@...il.com>,
	Patrice Chotard <patrice.chotard@...com>,
	<marcel.ziswiler@...adex.com>, <stefan@...er.ch>, <dev@...xeye.de>
Subject: [PATCH v2 04/10] gpio: stmpe: write int status register only when needed

From: Patrice Chotard <patrice.chotard@...com>

On STMPE801/1801 datasheets, it's mentionned writing
in interrupt status register has no effect, bits are
cleared when reading.

Signed-off-by: Amelie DELAUNAY <amelie.delaunay@...com>
Signed-off-by: Patrice Chotard <patrice.chotard@...com>
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
---
 drivers/gpio/gpio-stmpe.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-stmpe.c b/drivers/gpio/gpio-stmpe.c
index bfc918c..2789bdc 100644
--- a/drivers/gpio/gpio-stmpe.c
+++ b/drivers/gpio/gpio-stmpe.c
@@ -355,12 +355,16 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
 			stat &= ~(1 << bit);
 		}
 
-		stmpe_reg_write(stmpe, statmsbreg + i, status[i]);
-
-		/* Edge detect register is not present on 801 and 1801 */
-		if (stmpe->partnum != STMPE801 || stmpe->partnum != STMPE1801)
+		/*
+		 * interrupt status register write has no effect on
+		 * 801 and 1801, bits are cleared when read.
+		 * Edge detect register is not present on 801 and 1801
+		 */
+		if (stmpe->partnum != STMPE801 || stmpe->partnum != STMPE1801) {
+			stmpe_reg_write(stmpe, statmsbreg + i, status[i]);
 			stmpe_reg_write(stmpe, stmpe->regs[STMPE_IDX_GPEDR_MSB]
 					+ i, status[i]);
+		}
 	}
 
 	return IRQ_HANDLED;
-- 
1.9.1