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authorDmitry Osipenko <digetx@gmail.com>2019-09-26 22:17:54 +0300
committerThierry Reding <treding@nvidia.com>2019-10-29 14:35:06 +0100
commite57a243f5d896f02510e4be92df0873b4c1aab7f (patch)
treebb119a9b58bc7e2ad279f20b1409ede4340c9a3b /drivers/soc/tegra/pmc.c
parent783807436f363e5b1ad4d43ba7debbedfcadbb99 (diff)
downloadlinux-e57a243f5d896f02510e4be92df0873b4c1aab7f.tar.bz2
soc/tegra: pmc: Query PCLK clock rate at probe time
It is possible to get a lockup if kernel decides to enter LP2 cpuidle from some clk-notifier, in that case CCF's "prepare" mutex is kept locked and thus clk_get_rate(pclk) blocks on the same mutex with interrupts being disabled, hanging machine. Signed-off-by: Dmitry Osipenko <digetx@gmail.com> Acked-By: Peter De Schrijver <pdeschrijver@nvidia.com> Signed-off-by: Thierry Reding <treding@nvidia.com>
Diffstat (limited to 'drivers/soc/tegra/pmc.c')
-rw-r--r--drivers/soc/tegra/pmc.c74
1 files changed, 59 insertions, 15 deletions
diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
index c9b1baae5d8a..1f78e8497fde 100644
--- a/drivers/soc/tegra/pmc.c
+++ b/drivers/soc/tegra/pmc.c
@@ -324,6 +324,7 @@ static const char * const tegra210_reset_sources[] = {
* @pctl_dev: pin controller exposed by the PMC
* @domain: IRQ domain provided by the PMC
* @irq: chip implementation for the IRQ domain
+ * @clk_nb: pclk clock changes handler
*/
struct tegra_pmc {
struct device *dev;
@@ -359,6 +360,8 @@ struct tegra_pmc {
struct irq_domain *domain;
struct irq_chip irq;
+
+ struct notifier_block clk_nb;
};
static struct tegra_pmc *pmc = &(struct tegra_pmc) {
@@ -1207,7 +1210,7 @@ static int tegra_io_pad_prepare(struct tegra_pmc *pmc, enum tegra_io_pad id,
return err;
if (pmc->clk) {
- rate = clk_get_rate(pmc->clk);
+ rate = pmc->rate;
if (!rate) {
dev_err(pmc->dev, "failed to get clock rate\n");
return -ENODEV;
@@ -1448,6 +1451,7 @@ void tegra_pmc_set_suspend_mode(enum tegra_suspend_mode mode)
void tegra_pmc_enter_suspend_mode(enum tegra_suspend_mode mode)
{
unsigned long long rate = 0;
+ u64 ticks;
u32 value;
switch (mode) {
@@ -1456,7 +1460,7 @@ void tegra_pmc_enter_suspend_mode(enum tegra_suspend_mode mode)
break;
case TEGRA_SUSPEND_LP2:
- rate = clk_get_rate(pmc->clk);
+ rate = pmc->rate;
break;
default:
@@ -1466,21 +1470,15 @@ void tegra_pmc_enter_suspend_mode(enum tegra_suspend_mode mode)
if (WARN_ON_ONCE(rate == 0))
rate = 100000000;
- if (rate != pmc->rate) {
- u64 ticks;
-
- ticks = pmc->cpu_good_time * rate + USEC_PER_SEC - 1;
- do_div(ticks, USEC_PER_SEC);
- tegra_pmc_writel(pmc, ticks, PMC_CPUPWRGOOD_TIMER);
+ ticks = pmc->cpu_good_time * rate + USEC_PER_SEC - 1;
+ do_div(ticks, USEC_PER_SEC);
+ tegra_pmc_writel(pmc, ticks, PMC_CPUPWRGOOD_TIMER);
- ticks = pmc->cpu_off_time * rate + USEC_PER_SEC - 1;
- do_div(ticks, USEC_PER_SEC);
- tegra_pmc_writel(pmc, ticks, PMC_CPUPWROFF_TIMER);
+ ticks = pmc->cpu_off_time * rate + USEC_PER_SEC - 1;
+ do_div(ticks, USEC_PER_SEC);
+ tegra_pmc_writel(pmc, ticks, PMC_CPUPWROFF_TIMER);
- wmb();
-
- pmc->rate = rate;
- }
+ wmb();
value = tegra_pmc_readl(pmc, PMC_CNTRL);
value &= ~PMC_CNTRL_SIDE_EFFECT_LP0;
@@ -2140,6 +2138,33 @@ static int tegra_pmc_irq_init(struct tegra_pmc *pmc)
return 0;
}
+static int tegra_pmc_clk_notify_cb(struct notifier_block *nb,
+ unsigned long action, void *ptr)
+{
+ struct tegra_pmc *pmc = container_of(nb, struct tegra_pmc, clk_nb);
+ struct clk_notifier_data *data = ptr;
+
+ switch (action) {
+ case PRE_RATE_CHANGE:
+ mutex_lock(&pmc->powergates_lock);
+ break;
+
+ case POST_RATE_CHANGE:
+ pmc->rate = data->new_rate;
+ /* fall through */
+
+ case ABORT_RATE_CHANGE:
+ mutex_unlock(&pmc->powergates_lock);
+ break;
+
+ default:
+ WARN_ON_ONCE(1);
+ return notifier_from_errno(-EINVAL);
+ }
+
+ return NOTIFY_OK;
+}
+
static int tegra_pmc_probe(struct platform_device *pdev)
{
void __iomem *base;
@@ -2203,6 +2228,23 @@ static int tegra_pmc_probe(struct platform_device *pdev)
pmc->clk = NULL;
}
+ /*
+ * PCLK clock rate can't be retrieved using CLK API because it
+ * causes lockup if CPU enters LP2 idle state from some other
+ * CLK notifier, hence we're caching the rate's value locally.
+ */
+ if (pmc->clk) {
+ pmc->clk_nb.notifier_call = tegra_pmc_clk_notify_cb;
+ err = clk_notifier_register(pmc->clk, &pmc->clk_nb);
+ if (err) {
+ dev_err(&pdev->dev,
+ "failed to register clk notifier\n");
+ return err;
+ }
+
+ pmc->rate = clk_get_rate(pmc->clk);
+ }
+
pmc->dev = &pdev->dev;
tegra_pmc_init(pmc);
@@ -2254,6 +2296,8 @@ cleanup_debugfs:
cleanup_sysfs:
device_remove_file(&pdev->dev, &dev_attr_reset_reason);
device_remove_file(&pdev->dev, &dev_attr_reset_level);
+ clk_notifier_unregister(pmc->clk, &pmc->clk_nb);
+
return err;
}