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    Subject[PATCH 5.10 163/717] mfd: cpcap: Fix interrupt regression with regmap clear_ack
    Date
    From: Tony Lindgren <tony@atomide.com>

    [ Upstream commit 14639a22de657eabbb776f503a816594393cc935 ]

    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>
    Tested-by: Pavel Machek <pavel@ucw.cz>
    Reviewed-By: Tim Harvey <tharvey@gateworks.com>
    Signed-off-by: Lee Jones <lee.jones@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    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
    index 2283d88adcc25..30d82bfe5b02f 100644
    --- 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,
    },
    };

    --
    2.27.0


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