From: Chris Packham chris.packham@alliedtelesis.co.nz
commit a74c313aca266fab0d1d1a72becbb8b7b5286b6e upstream.
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: 4a8ac5e45cda ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/i2c/busses/i2c-mpc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -636,7 +636,7 @@ static irqreturn_t mpc_i2c_isr(int irq, 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;