[PATCH v3 0/8] Few more cleanups for tegra-timer

[PATCH v3 0/8] Few more cleanups for tegra-timer

[Dmitry Osipenko]

Hello,

This a followup to [0] that includes some more fixes and further
prettifies the driver's code.

[0] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=111529

Changelog:

v3: Addressed request from Jon Hunter that was made in a review comment
    to v2 by dropping the timer's period rounding-up in the "Set and use
    timer' period" patch.

    Appended two new patches to this series that were already sent out
    and reviewed after the v2 of this series:

      clocksource/drivers/tegra: Cycles can't be 0
      clocksource/drivers/tegra: Set up maximum-ticks limit properly

    In this two new patches I addressed review comments that were made by
    Thierry Reding by adding clarifying comments to the code and extending
    the commit messages a tad.

    Corrected the "Fixes" tag in a "Restore timer rate on Tegra210"
    patch such that linux-next checker won't complain about the shortened
    commit's subject.

v2: Fixed a bug that was introduced by [0] in a newly added patch:
    "Restore timer rate on Tegra210".

    Fixed potential problem in regards to error handling in another new
    patch: "Restore base address before cleanup".

    Added new patch "Add verbose definition for 1MHz constant" as per
    Daniel's Lezcano recommendation.

    Fixed a code typo that was made in "Remove duplicated use of per_cpu_ptr"
    of v1.

Dmitry Osipenko (8):
  clocksource/drivers/tegra: Restore timer rate on Tegra210
  clocksource/drivers/tegra: Remove duplicated use of per_cpu_ptr
  clocksource/drivers/tegra: Set and use timer's period
  clocksource/drivers/tegra: Drop unneeded typecasting in one place
  clocksource/drivers/tegra: Add verbose definition for 1MHz constant
  clocksource/drivers/tegra: Restore base address before cleanup
  clocksource/drivers/tegra: Cycles can't be 0
  clocksource/drivers/tegra: Set up maximum-ticks limit properly

 drivers/clocksource/timer-tegra.c | 82 +++++++++++++++++++++----------
 1 file changed, 56 insertions(+), 26 deletions(-)

-- 
2.22.0

[PATCH v3 1/8] clocksource/drivers/tegra: Restore timer rate on Tegra210

[Dmitry Osipenko]

The clocksource rate is initialized only for the first per-CPU clocksource
and then that rate shall be replicated for the rest of clocksource's
because they are initialized manually in the code.

Fixes: 3be2a85a0b61 ("clocksource/drivers/tegra: Support per-CPU timers on all Tegra's")
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index 1cc5847a1030..501071f09fa8 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -277,6 +277,8 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 		 */
 		if (tegra20)
 			cpu_to->of_clk.rate = 1000000;
+		else
+			cpu_to->of_clk.rate = timer_of_rate(to);
 
 		cpu_to = per_cpu_ptr(&tegra_to, cpu);
 		cpu_to->of_base.base = timer_reg_base + base;
-- 
2.22.0

Re: [PATCH v3 1/8] clocksource/drivers/tegra: Restore timer rate on Tegra210

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 651 bytes --]

On Tue, Jun 18, 2019 at 05:03:51PM +0300, Dmitry Osipenko wrote:
> The clocksource rate is initialized only for the first per-CPU clocksource
> and then that rate shall be replicated for the rest of clocksource's
> because they are initialized manually in the code.
> 
> Fixes: 3be2a85a0b61 ("clocksource/drivers/tegra: Support per-CPU timers on all Tegra's")
> Acked-by: Jon Hunter <jonathanh@nvidia.com>
> Tested-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 2 ++
>  1 file changed, 2 insertions(+)

Acked-by: Thierry Reding <treding@nvidia.com>

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[PATCH v3 2/8] clocksource/drivers/tegra: Remove duplicated use of per_cpu_ptr

[Dmitry Osipenko]

It was left unnoticed by accident, which means that the code could be
cleaned up a tad more.

Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 42 ++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index 501071f09fa8..ff5a4ccb5d52 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -216,6 +216,19 @@ static inline unsigned int tegra_irq_idx_for_cpu(int cpu, bool tegra20)
 	return TIMER10_IRQ_IDX + cpu;
 }
 
+static inline unsigned long tegra_rate_for_timer(struct timer_of *to,
+						 bool tegra20)
+{
+	/*
+	 * TIMER1-9 are fixed to 1MHz, TIMER10-13 are running off the
+	 * parent clock.
+	 */
+	if (tegra20)
+		return 1000000;
+
+	return timer_of_rate(to);
+}
+
 static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 				   int rating)
 {
@@ -268,32 +281,27 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 
 	for_each_possible_cpu(cpu) {
 		struct timer_of *cpu_to = per_cpu_ptr(&tegra_to, cpu);
+		unsigned long flags = IRQF_TIMER | IRQF_NOBALANCING;
+		unsigned long rate = tegra_rate_for_timer(to, tegra20);
 		unsigned int base = tegra_base_for_cpu(cpu, tegra20);
 		unsigned int idx = tegra_irq_idx_for_cpu(cpu, tegra20);
+		unsigned int irq = irq_of_parse_and_map(np, idx);
 
-		/*
-		 * TIMER1-9 are fixed to 1MHz, TIMER10-13 are running off the
-		 * parent clock.
-		 */
-		if (tegra20)
-			cpu_to->of_clk.rate = 1000000;
-		else
-			cpu_to->of_clk.rate = timer_of_rate(to);
-
-		cpu_to = per_cpu_ptr(&tegra_to, cpu);
-		cpu_to->of_base.base = timer_reg_base + base;
-		cpu_to->clkevt.rating = rating;
-		cpu_to->clkevt.cpumask = cpumask_of(cpu);
-		cpu_to->clkevt.irq = irq_of_parse_and_map(np, idx);
-		if (!cpu_to->clkevt.irq) {
+		if (!irq) {
 			pr_err("failed to map irq for cpu%d\n", cpu);
 			ret = -EINVAL;
 			goto out_irq;
 		}
 
+		cpu_to->clkevt.irq = irq;
+		cpu_to->clkevt.rating = rating;
+		cpu_to->clkevt.cpumask = cpumask_of(cpu);
+		cpu_to->of_base.base = timer_reg_base + base;
+		cpu_to->of_clk.rate = rate;
+
 		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);
-		ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr,
-				  IRQF_TIMER | IRQF_NOBALANCING,
+
+		ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr, flags,
 				  cpu_to->clkevt.name, &cpu_to->clkevt);
 		if (ret) {
 			pr_err("failed to set up irq for cpu%d: %d\n",
-- 
2.22.0

Re: [PATCH v3 2/8] clocksource/drivers/tegra: Remove duplicated use of per_cpu_ptr

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 454 bytes --]

On Tue, Jun 18, 2019 at 05:03:52PM +0300, Dmitry Osipenko wrote:
> It was left unnoticed by accident, which means that the code could be
> cleaned up a tad more.
> 
> Acked-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 42 ++++++++++++++++++-------------
>  1 file changed, 25 insertions(+), 17 deletions(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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[PATCH v3 3/8] clocksource/drivers/tegra: Set and use timer's period

[Dmitry Osipenko]

The of_clk structure has a period field that is set up initially by
timer_of_clk_init(), that period value need to be adjusted for a case of
TIMER1-9 that are running at a fixed rate that doesn't match the clock's
rate. Note that the period value is currently used only by some of the
clocksource drivers internally and hence this is just a minor cleanup
change that doesn't fix anything.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index ff5a4ccb5d52..e6221e070499 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -71,9 +71,9 @@ static int tegra_timer_shutdown(struct clock_event_device *evt)
 static int tegra_timer_set_periodic(struct clock_event_device *evt)
 {
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
+	unsigned long period = timer_of_period(to_timer_of(evt));
 
-	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER |
-		       ((timer_of_rate(to_timer_of(evt)) / HZ) - 1),
+	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1),
 		       reg_base + TIMER_PTV);
 
 	return 0;
@@ -297,6 +297,7 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 		cpu_to->clkevt.rating = rating;
 		cpu_to->clkevt.cpumask = cpumask_of(cpu);
 		cpu_to->of_base.base = timer_reg_base + base;
+		cpu_to->of_clk.period = rate / HZ;
 		cpu_to->of_clk.rate = rate;
 
 		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);
-- 
2.22.0

Re: [PATCH v3 3/8] clocksource/drivers/tegra: Set and use timer's period

[Jon Hunter]

On 18/06/2019 15:03, Dmitry Osipenko wrote:
> The of_clk structure has a period field that is set up initially by
> timer_of_clk_init(), that period value need to be adjusted for a case of
> TIMER1-9 that are running at a fixed rate that doesn't match the clock's
> rate. Note that the period value is currently used only by some of the
> clocksource drivers internally and hence this is just a minor cleanup
> change that doesn't fix anything.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
> index ff5a4ccb5d52..e6221e070499 100644
> --- a/drivers/clocksource/timer-tegra.c
> +++ b/drivers/clocksource/timer-tegra.c
> @@ -71,9 +71,9 @@ static int tegra_timer_shutdown(struct clock_event_device *evt)
>  static int tegra_timer_set_periodic(struct clock_event_device *evt)
>  {
>  	void __iomem *reg_base = timer_of_base(to_timer_of(evt)); 
> +	unsigned long period = timer_of_period(to_timer_of(evt));
>  
> -	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER |
> -		       ((timer_of_rate(to_timer_of(evt)) / HZ) - 1),
> +	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1),
>  		       reg_base + TIMER_PTV);
>  
>  	return 0;
> @@ -297,6 +297,7 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
>  		cpu_to->clkevt.rating = rating;
>  		cpu_to->clkevt.cpumask = cpumask_of(cpu);
>  		cpu_to->of_base.base = timer_reg_base + base;
> +		cpu_to->of_clk.period = rate / HZ;
>  		cpu_to->of_clk.rate = rate;
>  
>  		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);

Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

-- 
nvpublic

Re: [PATCH v3 3/8] clocksource/drivers/tegra: Set and use timer's period

[Dmitry Osipenko]

18.06.2019 19:32, Jon Hunter пишет:
> 
> On 18/06/2019 15:03, Dmitry Osipenko wrote:
>> The of_clk structure has a period field that is set up initially by
>> timer_of_clk_init(), that period value need to be adjusted for a case of
>> TIMER1-9 that are running at a fixed rate that doesn't match the clock's
>> rate. Note that the period value is currently used only by some of the
>> clocksource drivers internally and hence this is just a minor cleanup
>> change that doesn't fix anything.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/clocksource/timer-tegra.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
>> index ff5a4ccb5d52..e6221e070499 100644
>> --- a/drivers/clocksource/timer-tegra.c
>> +++ b/drivers/clocksource/timer-tegra.c
>> @@ -71,9 +71,9 @@ static int tegra_timer_shutdown(struct clock_event_device *evt)
>>  static int tegra_timer_set_periodic(struct clock_event_device *evt)
>>  {
>>  	void __iomem *reg_base = timer_of_base(to_timer_of(evt)); 
>> +	unsigned long period = timer_of_period(to_timer_of(evt));
>>  
>> -	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER |
>> -		       ((timer_of_rate(to_timer_of(evt)) / HZ) - 1),
>> +	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1),
>>  		       reg_base + TIMER_PTV);
>>  
>>  	return 0;
>> @@ -297,6 +297,7 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
>>  		cpu_to->clkevt.rating = rating;
>>  		cpu_to->clkevt.cpumask = cpumask_of(cpu);
>>  		cpu_to->of_base.base = timer_reg_base + base;
>> +		cpu_to->of_clk.period = rate / HZ;
>>  		cpu_to->of_clk.rate = rate;
>>  
>>  		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);
> 
> Acked-by: Jon Hunter <jonathanh@nvidia.com>

Thanks!

Re: [PATCH v3 3/8] clocksource/drivers/tegra: Set and use timer's period

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 686 bytes --]

On Tue, Jun 18, 2019 at 05:03:53PM +0300, Dmitry Osipenko wrote:
> The of_clk structure has a period field that is set up initially by
> timer_of_clk_init(), that period value need to be adjusted for a case of
> TIMER1-9 that are running at a fixed rate that doesn't match the clock's
> rate. Note that the period value is currently used only by some of the
> clocksource drivers internally and hence this is just a minor cleanup
> change that doesn't fix anything.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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[PATCH v3 4/8] clocksource/drivers/tegra: Drop unneeded typecasting in one place

[Dmitry Osipenko]

There is no need to cast void because kernel allows to do that without
a warning message from a compiler.

Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index e6221e070499..3afa66c6730b 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -81,7 +81,7 @@ static int tegra_timer_set_periodic(struct clock_event_device *evt)
 
 static irqreturn_t tegra_timer_isr(int irq, void *dev_id)
 {
-	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
+	struct clock_event_device *evt = dev_id;
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
 
 	writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
-- 
2.22.0

Re: [PATCH v3 4/8] clocksource/drivers/tegra: Drop unneeded typecasting in one place

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 433 bytes --]

On Tue, Jun 18, 2019 at 05:03:54PM +0300, Dmitry Osipenko wrote:
> There is no need to cast void because kernel allows to do that without
> a warning message from a compiler.
> 
> Acked-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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[PATCH v3 5/8] clocksource/drivers/tegra: Add verbose definition for 1MHz constant

[Dmitry Osipenko]

Convert all 1MHz literals to a verbose constant for better readability.

Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index 3afa66c6730b..ddf5531c48a9 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -44,6 +44,8 @@
 #define TIMER1_IRQ_IDX		0
 #define TIMER10_IRQ_IDX		10
 
+#define TIMER_1MHz		1000000
+
 static u32 usec_config;
 static void __iomem *timer_reg_base;
 
@@ -158,7 +160,7 @@ static unsigned long tegra_delay_timer_read_counter_long(void)
 
 static struct delay_timer tegra_delay_timer = {
 	.read_current_timer = tegra_delay_timer_read_counter_long,
-	.freq = 1000000,
+	.freq = TIMER_1MHz,
 };
 #endif
 
@@ -224,7 +226,7 @@ static inline unsigned long tegra_rate_for_timer(struct timer_of *to,
 	 * parent clock.
 	 */
 	if (tegra20)
-		return 1000000;
+		return TIMER_1MHz;
 
 	return timer_of_rate(to);
 }
@@ -313,11 +315,11 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 		}
 	}
 
-	sched_clock_register(tegra_read_sched_clock, 32, 1000000);
+	sched_clock_register(tegra_read_sched_clock, 32, TIMER_1MHz);
 
 	ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
-				    "timer_us", 1000000,
-				    300, 32, clocksource_mmio_readl_up);
+				    "timer_us", TIMER_1MHz, 300, 32,
+				    clocksource_mmio_readl_up);
 	if (ret)
 		pr_err("failed to register clocksource: %d\n", ret);
 
-- 
2.22.0

Re: [PATCH v3 5/8] clocksource/drivers/tegra: Add verbose definition for 1MHz constant

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 469 bytes --]

On Tue, Jun 18, 2019 at 05:03:55PM +0300, Dmitry Osipenko wrote:
> Convert all 1MHz literals to a verbose constant for better readability.
> 
> Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> Acked-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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[PATCH v3 6/8] clocksource/drivers/tegra: Restore base address before cleanup

[Dmitry Osipenko]

We're adjusting the timer's base for each per-CPU timer to point to the
actual start of the timer since device-tree defines a compound registers
range that includes all of the timers. In this case the original base
need to be restore before calling iounmap to unmap the proper address.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index ddf5531c48a9..2673b6e0caa8 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -345,6 +345,8 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 			irq_dispose_mapping(cpu_to->clkevt.irq);
 		}
 	}
+
+	to->of_base.base = timer_reg_base;
 out:
 	timer_of_cleanup(to);
 
-- 
2.22.0

Re: [PATCH v3 6/8] clocksource/drivers/tegra: Restore base address before cleanup

[Jon Hunter]

On 18/06/2019 15:03, Dmitry Osipenko wrote:
> We're adjusting the timer's base for each per-CPU timer to point to the
> actual start of the timer since device-tree defines a compound registers
> range that includes all of the timers. In this case the original base
> need to be restore before calling iounmap to unmap the proper address.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
> index ddf5531c48a9..2673b6e0caa8 100644
> --- a/drivers/clocksource/timer-tegra.c
> +++ b/drivers/clocksource/timer-tegra.c
> @@ -345,6 +345,8 @@ static int __init tegra_init_timer(struct device_node *np, bool tegra20,
>  			irq_dispose_mapping(cpu_to->clkevt.irq);
>  		}
>  	}
> +
> +	to->of_base.base = timer_reg_base;
>  out:
>  	timer_of_cleanup(to);


Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

-- 
nvpublic

Re: [PATCH v3 6/8] clocksource/drivers/tegra: Restore base address before cleanup

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 558 bytes --]

On Tue, Jun 18, 2019 at 05:03:56PM +0300, Dmitry Osipenko wrote:
> We're adjusting the timer's base for each per-CPU timer to point to the
> actual start of the timer since device-tree defines a compound registers
> range that includes all of the timers. In this case the original base
> need to be restore before calling iounmap to unmap the proper address.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 2 ++
>  1 file changed, 2 insertions(+)

Acked-by: Thierry Reding <treding@nvidia.com>

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[PATCH v3 7/8] clocksource/drivers/tegra: Cycles can't be 0

[Dmitry Osipenko]

Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after
one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks
are defined by clockevents_config_and_register(min, max) invocation and
the min value is set to 1 tick. Hence "cycles" value can't ever be 0,
unless it's a bug in clocksource core.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index 2673b6e0caa8..b84324288749 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -54,9 +54,16 @@ static int tegra_timer_set_next_event(unsigned long cycles,
 {
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
 
-	writel_relaxed(TIMER_PTV_EN |
-		       ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */
-		       reg_base + TIMER_PTV);
+	/*
+	 * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
+	 * fire after one tick if 0 is loaded.
+	 *
+	 * The minimum and maximum numbers of oneshot ticks are defined
+	 * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation
+	 * below in the code. Hence the cycles (ticks) can't be outside of
+	 * a range supportable by hardware.
+	 */
+	writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV);
 
 	return 0;
 }
-- 
2.22.0

Re: [PATCH v3 7/8] clocksource/drivers/tegra: Cycles can't be 0

[Jon Hunter]

On 18/06/2019 15:03, Dmitry Osipenko wrote:
> Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after
> one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks
> are defined by clockevents_config_and_register(min, max) invocation and
> the min value is set to 1 tick. Hence "cycles" value can't ever be 0,
> unless it's a bug in clocksource core.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
> index 2673b6e0caa8..b84324288749 100644
> --- a/drivers/clocksource/timer-tegra.c
> +++ b/drivers/clocksource/timer-tegra.c
> @@ -54,9 +54,16 @@ static int tegra_timer_set_next_event(unsigned long cycles,
>  {
>  	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
>  
> -	writel_relaxed(TIMER_PTV_EN |
> -		       ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */
> -		       reg_base + TIMER_PTV);
> +	/*
> +	 * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
> +	 * fire after one tick if 0 is loaded.
> +	 *
> +	 * The minimum and maximum numbers of oneshot ticks are defined
> +	 * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation
> +	 * below in the code. Hence the cycles (ticks) can't be outside of
> +	 * a range supportable by hardware.
> +	 */
> +	writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV);
>  
>  	return 0;
>  }
> 


Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

-- 
nvpublic

Re: [PATCH v3 7/8] clocksource/drivers/tegra: Cycles can't be 0

[Thierry Reding]

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On Tue, Jun 18, 2019 at 05:03:57PM +0300, Dmitry Osipenko wrote:
> Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after
> one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks
> are defined by clockevents_config_and_register(min, max) invocation and
> the min value is set to 1 tick. Hence "cycles" value can't ever be 0,
> unless it's a bug in clocksource core.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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Re: [PATCH v3 7/8] clocksource/drivers/tegra: Cycles can't be 0

[Dmitry Osipenko]

19.06.2019 11:19, Thierry Reding пишет:
> On Tue, Jun 18, 2019 at 05:03:57PM +0300, Dmitry Osipenko wrote:
>> Tegra's timer uses n+1 scheme for the counter, i.e. timer will fire after
>> one tick if 0 is loaded. The minimum and maximum numbers of oneshot ticks
>> are defined by clockevents_config_and_register(min, max) invocation and
>> the min value is set to 1 tick. Hence "cycles" value can't ever be 0,
>> unless it's a bug in clocksource core.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>> ---
>>  drivers/clocksource/timer-tegra.c | 13 ++++++++++---
>>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> Acked-by: Thierry Reding <treding@nvidia.com>
> 

Thanks!

[PATCH v3 8/8] clocksource/drivers/tegra: Set up maximum-ticks limit properly

[Dmitry Osipenko]

Tegra's timer has 29 bits for the counter and for the "load" register
which sets counter to a load-value. The counter's value is lower than
the actual value by 1 because it starts to decrement after one tick,
hence the maximum number of ticks that hardware can handle equals to
29 bits + 1.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/clocksource/timer-tegra.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
index b84324288749..355b29ff6362 100644
--- a/drivers/clocksource/timer-tegra.c
+++ b/drivers/clocksource/timer-tegra.c
@@ -137,9 +137,17 @@ static int tegra_timer_setup(unsigned int cpu)
 	irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
 	enable_irq(to->clkevt.irq);
 
+	/*
+	 * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
+	 * fire after one tick if 0 is loaded and thus minimum number of
+	 * ticks is 1. In result both of the clocksource's tick limits are
+	 * higher than a minimum and maximum that hardware register can
+	 * take by 1, this is then taken into account by set_next_event
+	 * callback.
+	 */
 	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
 					1, /* min */
-					0x1fffffff); /* 29 bits */
+					0x1fffffff + 1); /* max 29 bits + 1 */
 
 	return 0;
 }
-- 
2.22.0

Re: [PATCH v3 8/8] clocksource/drivers/tegra: Set up maximum-ticks limit properly

[Jon Hunter]

On 18/06/2019 15:03, Dmitry Osipenko wrote:
> Tegra's timer has 29 bits for the counter and for the "load" register
> which sets counter to a load-value. The counter's value is lower than
> the actual value by 1 because it starts to decrement after one tick,
> hence the maximum number of ticks that hardware can handle equals to
> 29 bits + 1.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c
> index b84324288749..355b29ff6362 100644
> --- a/drivers/clocksource/timer-tegra.c
> +++ b/drivers/clocksource/timer-tegra.c
> @@ -137,9 +137,17 @@ static int tegra_timer_setup(unsigned int cpu)
>  	irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
>  	enable_irq(to->clkevt.irq);
>  
> +	/*
> +	 * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
> +	 * fire after one tick if 0 is loaded and thus minimum number of
> +	 * ticks is 1. In result both of the clocksource's tick limits are
> +	 * higher than a minimum and maximum that hardware register can
> +	 * take by 1, this is then taken into account by set_next_event
> +	 * callback.
> +	 */
>  	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
>  					1, /* min */
> -					0x1fffffff); /* 29 bits */
> +					0x1fffffff + 1); /* max 29 bits + 1 */
>  
>  	return 0;
>  }
> 


Acked-by: Jon Hunter <jonathanh@nvidia.com>

Cheers
Jon

-- 
nvpublic

Re: [PATCH v3 8/8] clocksource/drivers/tegra: Set up maximum-ticks limit properly

[Thierry Reding]

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On Tue, Jun 18, 2019 at 05:03:58PM +0300, Dmitry Osipenko wrote:
> Tegra's timer has 29 bits for the counter and for the "load" register
> which sets counter to a load-value. The counter's value is lower than
> the actual value by 1 because it starts to decrement after one tick,
> hence the maximum number of ticks that hardware can handle equals to
> 29 bits + 1.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/clocksource/timer-tegra.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)

Acked-by: Thierry Reding <treding@nvidia.com>

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