linux-kernel - [PATCH 2/4] soc: qcom: smp2p: Add proper retrigger detection

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Date:   Tue, 5 Jul 2022 23:02:09 -0700
From:   Chris Lew <quic_clew@...cinc.com>
To:     <agross@...nel.org>, <bjorn.andersson@...aro.org>,
        <konrad.dybcio@...ainline.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <quic_clew@...cinc.com>
Subject: [PATCH 2/4] soc: qcom: smp2p: Add proper retrigger detection

Currently, smp2p relies on the hwirq resend feature to retrigger irqs
that were missed because the irq was disabled at the time of receiving
it. The hwirq resend feature will retrigger the parent smp2p interrupt.
In order to keep track of what children needed to be retriggered, the
pending bitmap was added.

After calling handle_nested_irq, smp2p checks if the interrupt is
enabled and sets the pending bit if the interrupt is not enabled. There
is a small window where a client can enable the interrupt between
calling handle_nested_irq and checking if the interrupt is enabled.
If this happens, the interrupt is never called when the parent smp2p
interrupt is retriggered.

Add the irq_retrigger callback so smp2p can know which child interrupts
need to be retriggered. Set the pending bits accordingly.

Signed-off-by: Chris Lew <quic_clew@...cinc.com>
---
 drivers/soc/qcom/smp2p.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/soc/qcom/smp2p.c b/drivers/soc/qcom/smp2p.c
index 1c3259fe98be..a94cddcb0298 100644
--- a/drivers/soc/qcom/smp2p.c
+++ b/drivers/soc/qcom/smp2p.c
@@ -260,11 +260,7 @@ static void qcom_smp2p_notify_in(struct qcom_smp2p *smp2p)
 			    (!(val & BIT(i)) && test_bit(i, entry->irq_falling))) {
 				irq_pin = irq_find_mapping(entry->domain, i);
 				handle_nested_irq(irq_pin);
-
-				if (test_bit(i, entry->irq_enabled))
-					clear_bit(i, entry->irq_pending);
-				else
-					set_bit(i, entry->irq_pending);
+				clear_bit(i, entry->irq_pending);
 			}
 		}
 	}
@@ -353,11 +349,22 @@ static int smp2p_set_irq_type(struct irq_data *irqd, unsigned int type)
 	return 0;
 }

+static int smp2p_retrigger_irq(struct irq_data *irqd)
+{
+	struct smp2p_entry *entry = irq_data_get_irq_chip_data(irqd);
+	irq_hw_number_t irq = irqd_to_hwirq(irqd);
+
+	set_bit(irq, entry->irq_pending);
+
+	return 0;
+}
+
 static struct irq_chip smp2p_irq_chip = {
 	.name           = "smp2p",
 	.irq_mask       = smp2p_mask_irq,
 	.irq_unmask     = smp2p_unmask_irq,
 	.irq_set_type	= smp2p_set_irq_type,
+	.irq_retrigger	= smp2p_retrigger_irq,
 };

 static int smp2p_irq_map(struct irq_domain *d,
-- 
2.7.4