[PATCH] mfd: cpcap: Fix interrupt regression with regmap clear_ack

Tony Lindgren
2020-11-11T17:06:27Z

With commit 3a6f0fb7b8eb ("regmap: irq: Add support to clear ack
registers"), the cpcap interrupts are no longer getting acked properly
leading to a very unresponsive device with CPUs fully loaded spinning
in the threaded IRQ handlers.

To me it looks like the clear_ack commit above actually fixed a long
standing bug in regmap_irq_thread() where we unconditionally acked the
interrupts earlier without considering ack_invert. And the issue with
cpcap started happening as we now also consider ack_invert.

Tim Harvey <tharvey@gateworks.com> tried to fix this issue earlier with
"[PATCH v2] regmap: irq: fix ack-invert", but the reading of the ack
register was considered unnecessary for just ack_invert, and we did not
have clear_ack available yet. As the cpcap irqs worked both with and
without ack_invert earlier because of the unconditional ack, the
problem remained hidden until now.

Also, looks like the earlier v3.0.8 based Motorola Android Linux kernel
does clear_ack style read-clear-write with "ireg_val & ~mreg_val" instead
of just ack_invert style write. So let's switch cpcap to use clear_ack
to fix the issue.

Fixes: 3a6f0fb7b8eb ("regmap: irq: Add support to clear ack registers")
Cc: Carl Philipp Klemm <philipp@uvos.xyz>
Cc: Laxminath Kasam <lkasam@codeaurora.org>
Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
---
drivers/mfd/motorola-cpcap.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/motorola-cpcap.c b/drivers/mfd/motorola-cpcap.c
--- a/drivers/mfd/motorola-cpcap.c
+++ b/drivers/mfd/motorola-cpcap.c
@@ -97,7 +97,7 @@ static struct regmap_irq_chip cpcap_irq_chip[CPCAP_NR_IRQ_CHIPS] = {
.ack_base = CPCAP_REG_MI1,
.mask_base = CPCAP_REG_MIM1,
.use_ack = true,
- .ack_invert = true,
+ .clear_ack = true,
},
{
.name = "cpcap-m2",
@@ -106,7 +106,7 @@ static struct regmap_irq_chip cpcap_irq_chip[CPCAP_NR_IRQ_CHIPS] = {
.ack_base = CPCAP_REG_MI2,
.mask_base = CPCAP_REG_MIM2,
.use_ack = true,
- .ack_invert = true,
+ .clear_ack = true,
},
{
.name = "cpcap1-4",
@@ -115,7 +115,7 @@ static struct regmap_irq_chip cpcap_irq_chip[CPCAP_NR_IRQ_CHIPS] = {
.ack_base = CPCAP_REG_INT1,
.mask_base = CPCAP_REG_INTM1,
.use_ack = true,
- .ack_invert = true,
+ .clear_ack = true,
},
};

--
2.29.2