From: Stephan Gerhold stephan@gerhold.net
[ Upstream commit e3d4571955050736bbf3eda0a9538a09d9fcfce8 ]
The SMSM driver detects interrupt edges by tracking the last state it has seen (and has triggered the interrupt handler for). This works fine, but only if the interrupt does not change state while masked.
For example, if an interrupt is unmasked while the state is HIGH, the stored last_value for that interrupt might still be LOW. Then, when the remote processor triggers smsm_intr() we assume that nothing has changed, even though the state might have changed from HIGH to LOW.
Attempt to fix this by checking the current remote state before unmasking an IRQ. Use atomic operations to avoid the interrupt handler from interfering with the unmask function.
This fixes modem crashes in some edge cases with the BAM-DMUX driver. Specifically, the BAM-DMUX interrupt handler is not called for the HIGH -> LOW smsm state transition if the BAM-DMUX driver is loaded (and therefore unmasks the interrupt) after the modem was already started:
qcom-q6v5-mss 4080000.remoteproc: fatal error received: a2_task.c:3188: Assert FALSE failed: A2 DL PER deadlock timer expired waiting for Apps ACK
Fixes: c97c4090ff72 ("soc: qcom: smsm: Add driver for Qualcomm SMSM") Signed-off-by: Stephan Gerhold stephan@gerhold.net Link: https://lore.kernel.org/r/20210712135703.324748-2-stephan@gerhold.net Signed-off-by: Bjorn Andersson bjorn.andersson@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/soc/qcom/smsm.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/soc/qcom/smsm.c b/drivers/soc/qcom/smsm.c index d0337b2a71c8..783cb3364599 100644 --- a/drivers/soc/qcom/smsm.c +++ b/drivers/soc/qcom/smsm.c @@ -117,7 +117,7 @@ struct smsm_entry { DECLARE_BITMAP(irq_enabled, 32); DECLARE_BITMAP(irq_rising, 32); DECLARE_BITMAP(irq_falling, 32); - u32 last_value; + unsigned long last_value;
u32 *remote_state; u32 *subscription; @@ -212,8 +212,7 @@ static irqreturn_t smsm_intr(int irq, void *data) u32 val;
val = readl(entry->remote_state); - changed = val ^ entry->last_value; - entry->last_value = val; + changed = val ^ xchg(&entry->last_value, val);
for_each_set_bit(i, entry->irq_enabled, 32) { if (!(changed & BIT(i))) @@ -274,6 +273,12 @@ static void smsm_unmask_irq(struct irq_data *irqd) struct qcom_smsm *smsm = entry->smsm; u32 val;
+ /* Make sure our last cached state is up-to-date */ + if (readl(entry->remote_state) & BIT(irq)) + set_bit(irq, &entry->last_value); + else + clear_bit(irq, &entry->last_value); + set_bit(irq, entry->irq_enabled);
if (entry->subscription) {