Commit a74c313a authored Dec 07, 2021 by Chris Packham Committed by Wolfram Sang Dec 10, 2021

i2c: mpc: Use atomic read and fix break condition



Maxime points out that the polling code in mpc_i2c_isr should use the
_atomic API because it is called in an irq context and that the
behaviour of the MCF bit is that it is 1 when the byte transfer is
complete. All of this means the original code was effectively a
udelay(100).

Fix this by using readb_poll_timeout_atomic() and removing the negation
of the break condition.

Fixes: 4a8ac5e4 ("i2c: mpc: Poll for MCF")
Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

parent b503de23

drivers/i2c/busses/i2c-mpc.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -636,7 +636,7 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id)
		status = readb(i2c->base + MPC_I2C_SR);
		if (status & CSR_MIF) {
		/* Wait up to 100us for transfer to properly complete */
		readb_poll_timeout(i2c->base + MPC_I2C_SR, status, !(status & CSR_MCF), 0, 100);
		readb_poll_timeout_atomic(i2c->base + MPC_I2C_SR, status, status & CSR_MCF, 0, 100);
		writeb(0, i2c->base + MPC_I2C_SR);
		mpc_i2c_do_intr(i2c, status);
		return IRQ_HANDLED;