| From f8f913a456d059ab6943704eb2e823b3381d931b Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Fri, 16 Jul 2021 08:58:32 +1200 |
| Subject: i2c: mpc: Poll for MCF |
| |
| From: Chris Packham <chris.packham@alliedtelesis.co.nz> |
| |
| [ Upstream commit 4a8ac5e45cdaa88884b4ce05303e304cbabeb367 ] |
| |
| 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> |
| Signed-off-by: Wolfram Sang <wsa@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/i2c/busses/i2c-mpc.c | 4 ++-- |
| 1 file changed, 2 insertions(+), 2 deletions(-) |
| |
| 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; |
| -- |
| 2.30.2 |
| |
