the sdhci code provides both irq handlers: the primary and the thread
handler. Initially it was meant for the primary handler to be very
short.
The result is not that on -RT we have the primrary handler grabing locks
and this isn't really working. As a hack for now I just push both
handler into the threaded mode.
Reported-By: Michal Šmucr <msmucr@xxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
The "same thing" was reported against the iwlwifi driver
(request_threaded_irq(…, iwl_pcie_isr, iwl_pcie_irq_handler, …) and they
managed to rework it and not do anything that would break -RT in their
primary handler. Besides sdhci there are a few others drivers in the
same tree doing similar things.
I'm not sure what to do here in general. Motivating upstream maintainer
to rework their code or introducing IRQF_RT_SAFE and for others doing
the conversation like in the patch below.
Michal: This is untested but should fix the issue, reported.
drivers/mmc/host/sdhci.c | 32 +++++++++++++++++++++++++++-----
1 file changed, 27 insertions(+), 5 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 023c2010cd75..bcde53774bc9 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2565,6 +2565,31 @@ static irqreturn_t sdhci_thread_irq(int irq, void *dev_id)
return isr ? IRQ_HANDLED : IRQ_NONE;
}
+#ifdef CONFIG_PREEMPT_RT_BASE
+static irqreturn_t sdhci_rt_irq(int irq, void *dev_id)
+{
+ irqreturn_t ret;
+
+ local_bh_disable();
+ ret = sdhci_irq(irq, dev_id);
+ local_bh_enable();
+ if (ret == IRQ_WAKE_THREAD)
+ ret = sdhci_thread_irq(irq, dev_id);
+ return ret;
+}
+#endif
+
+static int sdhci_req_irq(struct sdhci_host *host)
+{
+#ifdef CONFIG_PREEMPT_RT_BASE
+ return request_threaded_irq(host->irq, NULL, sdhci_rt_irq,
+ IRQF_SHARED, mmc_hostname(host->mmc), host);
+#else
+ return request_threaded_irq(host->irq, sdhci_irq, sdhci_thread_irq,
+ IRQF_SHARED, mmc_hostname(host->mmc), host);
+#endif
+}
+
/*****************************************************************************\
* *
* Suspend/resume *
@@ -2632,9 +2657,7 @@ int sdhci_resume_host(struct sdhci_host *host)
}
if (!device_may_wakeup(mmc_dev(host->mmc))) {
- ret = request_threaded_irq(host->irq, sdhci_irq,
- sdhci_thread_irq, IRQF_SHARED,
- mmc_hostname(host->mmc), host);
+ ret = sdhci_req_irq(host);
if (ret)
return ret;
} else {
@@ -3253,8 +3276,7 @@ int sdhci_add_host(struct sdhci_host *host)
sdhci_init(host, 0);
- ret = request_threaded_irq(host->irq, sdhci_irq, sdhci_thread_irq,
- IRQF_SHARED, mmc_hostname(mmc), host);
+ ret = sdhci_req_irq(host);
if (ret) {
pr_err("%s: Failed to request IRQ %d: %d\n",
mmc_hostname(mmc), host->irq, ret);
--
2.1.4
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