Commit ec7aaca2 authored Jun 13, 2012 by Laxman Dewangan Committed by Wolfram Sang Jul 08, 2012

i2c: tegra: make sure register writes completes



The Tegra PPSB (an peripheral bus) queues writes transactions.
In order to guarantee that writes have completed before a
certain time, a read transaction to a register on the same
bus must be executed.
This is necessary in situations such as when clearing an
interrupt status or enable, so that when returning from an
interrupt handler, the HW has already de-asserted its
interrupt status output, which will avoid spurious interrupts.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

parent b4fde5e7

drivers/i2c/busses/i2c-tegra.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -165,6 +165,10 @@ static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
		unsigned long reg)
		{
		writel(val, i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));

		/* Read back register to make sure that register writes completed */
		if (reg != I2C_TX_FIFO)
		readl(i2c_dev->base + tegra_i2c_reg_addr(i2c_dev, reg));
		}

		static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)