On 05/30/2013 07:46 PM, Kevin Hilman wrote:
Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxx> writes:
If the i2c controller during suspend will generate an interrupt, it
can lead to unpredictable behaviour in the kernel.
Based on the logic of the kernel code interrupts from i2c should be
prohibited during suspend. Kernel writes 0 to the I2C_IE register in
the omap_i2c_runtime_suspend() function. In the other side kernel
writes saved interrupt flags to the I2C_IE register in
omap_i2c_runtime_resume() function. I.e. interrupts should be disabled
during suspend.
This works for chips with version1 registers scheme. Interrupts are
disabled during suspend. For chips with version2 scheme registers
writting 0 to the I2C_IE register does nothing (because now the
I2C_IRQENABLE_SET register is located at this address). This register
is used to enable interrupts. For disabling interrupts
I2C_IRQENABLE_CLR register should be used.
Because the registers I2C_IRQENABLE_SET and I2C_IE have the same
addresses, the interrupt enabling procedure is unchanged.
Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxx>
Much better, but still doesn't explain how/why this has been working up
until now. Have we just been lucky?
Yes, this has been working up until now because we've just been lucky.
---
drivers/i2c/busses/i2c-omap.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index e02f9e3..2419899 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -180,6 +180,8 @@ enum {
#define I2C_OMAP_ERRATA_I207 (1 << 0)
#define I2C_OMAP_ERRATA_I462 (1 << 1)
+#define OMAP_I2C_INTERRUPTS_MASK 0x6FFF
To be more clear, this should probably have v2 in the name.
I'll rename this mask in the patch-set v3
Kevin
--
Best regards,
Oleksandr Dmytryshyn | OMAP4 Platform
GlobalLogic Inc. | Innovation by Design
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