linux-kernel - [PATCH v3 2/3] spi: pxa2xx: Prepare for edge-triggered interrupts

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Message-ID: <e692c4a9-6320-b9e0-d6e7-f58bbe6ba867@siemens.com>
Date:   Thu, 19 Jan 2017 20:37:40 +0100
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Robert Jarzmik <robert.jarzmik@...e.fr>, linux-spi@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Sascha Weisenberger <sascha.weisenberger@...mens.com>
Subject: [PATCH v3 2/3] spi: pxa2xx: Prepare for edge-triggered interrupts

When using the a device with edge-triggered interrupts, such as MSIs,
the interrupt handler has to ensure that there is a point in time during
its execution where all interrupts sources are silent so that a new
event can trigger a new interrupt again.

This is achieved here by disabling all interrupt sources for a moment
before processing them according to the status register. If a new
interrupt should have arrived after we read the status, it will now
re-trigger the interrupt, even in edge mode.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
---

Successfully tested by now.

Changes to v2:
- avoid inner looping by making the hardware retrigger on "forgotten"
  IRQ sources

 drivers/spi/spi-pxa2xx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/spi/spi-pxa2xx.c b/drivers/spi/spi-pxa2xx.c
index 0d10090..f9c2329 100644
--- a/drivers/spi/spi-pxa2xx.c
+++ b/drivers/spi/spi-pxa2xx.c
@@ -785,6 +785,9 @@ static irqreturn_t ssp_int(int irq, void *dev_id)
 	if (!(status & mask))
 		return IRQ_NONE;
 
+	pxa2xx_spi_write(drv_data, SSCR1, sccr1_reg & ~drv_data->int_cr1);
+	pxa2xx_spi_write(drv_data, SSCR1, sccr1_reg);
+
 	if (!drv_data->master->cur_msg) {
 		handle_bad_msg(drv_data);
 		/* Never fail */
-- 
2.1.4



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