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i2c: mpc: Use atomic read and fix break condition

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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: 4a8ac5e45c ("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>
This commit is contained in:
Chris Packham 2021-12-07 17:21:44 +13:00 committed by Wolfram Sang
parent b503de239f
commit a74c313aca
1 changed files with 1 additions and 1 deletions
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drivers/i2c/busses/i2c-mpc.c
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@ -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;