From: Chris Packham Date: Fri, 2 Jul 2021 03:27:24 +0000 (+1200) Subject: i2c: mpc: Restore reread of I2C status register X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=763778cd79267dadf0ec7e044caf7563df0ab597;p=linux.git i2c: mpc: Restore reread of I2C status register Prior to commit 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") the old interrupt handler would reread MPC_I2C_SR after checking the CSR_MIF bit. When the driver was re-written this was removed as it seemed unnecessary. However as it turns out this is necessary for i2c devices which do clock stretching otherwise we end up thinking the bus is still busy when processing the interrupt. Fixes: 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") Signed-off-by: Chris Packham Signed-off-by: Wolfram Sang --- diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 30d9e89a3db20..2ee4a9361e404 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -564,6 +564,8 @@ 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); writeb(0, i2c->base + MPC_I2C_SR); mpc_i2c_do_intr(i2c, status); return IRQ_HANDLED;