lkml.org 
[lkml]   [2021]   [Jul]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2] i2c: mpc: Poll for MCF
Date
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(-)

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;
--
2.32.0
\
 
 \ /
  Last update: 2021-07-15 22:59    [W:0.283 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site