Commit 4a8ac5e4 authored by Chris Packham's avatar Chris Packham Committed by Wolfram Sang
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i2c: mpc: Poll for MCF 



During some transfers the bus can still be busy when an interrupt is
received. Commit 763778cd ("i2c: mpc: Restore reread of I2C status
register") attempted to address this by re-reading MPC_I2C_SR once but
that just made it less likely to happen without actually preventing it.
Instead of a single re-read, poll with a timeout so that the bus is given
enough time to settle but a genuine stuck SCL is still noticed.

Fixes: 1538d82f ("i2c: mpc: Interrupt driven transfer")
Signed-off-by: default avatarChris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: default avatarWolfram Sang <wsa@kernel.org>
parent a750bff5

drivers/i2c/busses/i2c-mpc.c

+2 −2
Original line number Diff line number Diff line
@@ -635,8 +635,8 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id) 


	status = readb(i2c->base + MPC_I2C_SR);

	if (status & CSR_MIF) {

		/* Read again to allow register to stabilise */

		status = readb(i2c->base + MPC_I2C_SR);

		/* Wait up to 100us for transfer to properly complete */

		readb_poll_timeout(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;