| Message ID | 20210715205832.17879-1-chris.packham@alliedtelesis.co.nz |
|---|---|
| State | Accepted |
| Commit | 4a8ac5e45cdaa88884b4ce05303e304cbabeb367 |
| Headers | show |
| Series | [v2] i2c: mpc: Poll for MCF | expand |
On Fri, Jul 16, 2021 at 08:58:32AM +1200, Chris Packham wrote: > During some transfers the bus can still be busy when an interrupt is > received. Commit 763778cd7926 ("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: 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") > Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Applied to for-current, thanks!
diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 6d5014ebaab5..a6ea1eb1394e 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -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;
During some transfers the bus can still be busy when an interrupt is received. Commit 763778cd7926 ("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: 1538d82f4647 ("i2c: mpc: Interrupt driven transfer") Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> --- Notes: Changes in v2: - grammar fix in commit message - add comment above poll drivers/i2c/busses/i2c-mpc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)