Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 7 March 2013 19:49, Russell King - ARM Linux wrote:
> So how is this different from any other clock which may also return zero
> from its clk_get_rate() ?
>
> If that's the condition you want to check for, call clk_get_rate() after
> a successful clk_get*() and check for the condition. Don't go treating
> the cookie somehow specially. You're *assuming* a behaviour that is
> inappropriate for the side of the interface you're working with.
Okay. I will replace the earlier fixup with following:
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index fdf54a9..87b7e48 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -9,8 +9,7 @@ config ARM_BIG_LITTLE_CPUFREQ
config ARM_DT_BL_CPUFREQ
tristate "Generic ARM big LITTLE CPUfreq driver probed via DT"
select ARM_BIG_LITTLE_CPUFREQ
- depends on OF
- default n
+ depends on OF && HAVE_CLK
help
This enables the Generic CPUfreq driver for ARM big.LITTLE platform.
This gets frequency tables from DT.
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 2486b9a..a41fd89 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -147,7 +147,7 @@ static void put_cluster_clk_and_freq_table(u32 cluster)
static int get_cluster_clk_and_freq_table(u32 cluster)
{
- char name[9] = "cluster";
+ char name[9] = "cpu-cluster";
int count;
if (atomic_inc_return(&cluster_usage[cluster]) != 1)
For more clarity i will resend this patch now will all updates.
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Thu, Mar 07, 2013 at 10:03:28AM +0800, Viresh Kumar wrote:
> On 7 March 2013 08:51, Russell King - ARM Linux
> wrote:
> > On Thu, Mar 07, 2013 at 08:32:37AM +0800, Viresh Kumar wrote:
> >> On 5 March 2013 18:52, Russell King - ARM Linux
> >> wrote:
> >> > On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
> >> >> + clk[cluster] = clk_get(NULL, name);
> >> >> + if (!IS_ERR_OR_NULL(clk[cluster])) {
> >> >
> >> > NAK. Two reasons.
> >> >
> >> > 1. IS_ERR_OR_NULL. You know about this, it's been on the list several
> >> >times.
> >>
> >> Hey, i had a second thought about this one and i have some other opinion
> >> here. This is a cpufreq driver and we need clock support for sure here, we
> >> can't work without it. And so here is the latest fixup:
> >
> > NAK. You just don't understand.
>
> Poor me!!
>
> I still remember the huge discussions we had during "clk: Add non
> CONFIG_HAVE_CLK routines" patchset.
>
> For others: https://lkml.org/lkml/2012/4/24/389
>
> Back to the discussion, I understand that clk_get() just returns a cookie and
> NULL is not an error and so it shouldn't be treated specially. And that's what
> we do with most of our drivers as all other clk routines (clk_get[set]_rate())
> have safe guards against the NULL clk, and they wouldn't complain.
>
> The special case we have in a cpufreq driver is, we can't work with
> zero returned
> from clk_get_rate()... That will make cpufreq driver work badly.
So how is this different from any other clock which may also return zero
from its clk_get_rate() ?
If that's the condition you want to check for, call clk_get_rate() after
a successful clk_get*() and check for the condition. Don't go treating
the cookie somehow specially. You're *assuming* a behaviour that is
inappropriate for the side of the interface you're working with.
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 7 March 2013 09:50, Olof Johansson wrote: > On Wed, Mar 6, 2013 at 5:46 PM, Olof Johansson wrote: > >> This binding makes no sense to me. It needs to be substantially better >> documented, not just a couple of sentences that people that understand >> bit.LITTLE thoroughly can make sense of. >> >> It also duplicates the cpu binding. I suspect this should instead be done >> through additions of the cpu bindings instead of duplication. So this needs >> to >> be substantially reworked. Actually, i wasn't getting in new bindings for cpu/cluster for big LITTLE but was just trying to get bindings for getting freq-table for cpufreq driver. Lorenzo (cc'd) actually has a patch for getting the bindings in and he is looking to send them soon. I know these can change after some review and the plan was i will fix cpufreq bindings again once that patch is in. We don't have any mainlined hardware for it for now and so it wouldn't break anything. > Also, _ALWAYS_ cc devicetree-discuss on new bindings. get_maintainer > tells you to do so. I knew it and i messed up with it. Will surely take care of it next time. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 7 March 2013 08:51, Russell King - ARM Linux wrote:
> On Thu, Mar 07, 2013 at 08:32:37AM +0800, Viresh Kumar wrote:
>> On 5 March 2013 18:52, Russell King - ARM Linux
>> wrote:
>> > On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
>> >> + clk[cluster] = clk_get(NULL, name);
>> >> + if (!IS_ERR_OR_NULL(clk[cluster])) {
>> >
>> > NAK. Two reasons.
>> >
>> > 1. IS_ERR_OR_NULL. You know about this, it's been on the list several
>> >times.
>>
>> Hey, i had a second thought about this one and i have some other opinion
>> here. This is a cpufreq driver and we need clock support for sure here, we
>> can't work without it. And so here is the latest fixup:
>
> NAK. You just don't understand.
Poor me!!
I still remember the huge discussions we had during "clk: Add non
CONFIG_HAVE_CLK routines" patchset.
For others: https://lkml.org/lkml/2012/4/24/389
Back to the discussion, I understand that clk_get() just returns a cookie and
NULL is not an error and so it shouldn't be treated specially. And that's what
we do with most of our drivers as all other clk routines (clk_get[set]_rate())
have safe guards against the NULL clk, and they wouldn't complain.
The special case we have in a cpufreq driver is, we can't work with
zero returned
from clk_get_rate()... That will make cpufreq driver work badly.
And that's why i got two additions
- depends on HAVE_CLK
- and using IS_ERR_OR_NULL
as NULL returned from clk_get is not a error but is not acceptable to
the cpufreq
driver.
Because i now have the HAVE_CLK dependency i am not sure if we can get NULL
returned from clk_get() at all. Can you get around something here?
--
viresh
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Wed, Mar 6, 2013 at 5:46 PM, Olof Johansson wrote: > This binding makes no sense to me. It needs to be substantially better > documented, not just a couple of sentences that people that understand > bit.LITTLE thoroughly can make sense of. > > It also duplicates the cpu binding. I suspect this should instead be done > through additions of the cpu bindings instead of duplication. So this needs to > be substantially reworked. Also, _ALWAYS_ cc devicetree-discuss on new bindings. get_maintainer tells you to do so. -Olof -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
> +++ b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt
> @@ -0,0 +1,29 @@
> +Generic ARM big LITTLE cpufreq driver's DT glue
> +---
> +
> +It is DT specific glue layer for generic cpufreq driver for big LITTLE
> systems.
> +
> +Both required and optional properties listed below must be defined under node
> +cluster*. * can be 0 or 1.
> +
> +Required properties:
> +- freqs: List of all supported frequencies.
> +
> +Optional properties:
> +- clock-latency: Specify the possible maximum transition latency for clock,
> in
> + unit of nanoseconds.
> +
> +Examples:
> +
> +cluster0: cluster@0 {
> +..
> +
> + freqs = <5 6 7 8 9 10
> 11 12>;
> + clock-latency = <20>;
> +
> + ..
> +
> +cores {
> + ..
> +};
> +};
This binding makes no sense to me. It needs to be substantially better
documented, not just a couple of sentences that people that understand
bit.LITTLE thoroughly can make sense of.
It also duplicates the cpu binding. I suspect this should instead be done
through additions of the cpu bindings instead of duplication. So this needs to
be substantially reworked.
-Olof
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 7 March 2013 08:49, Harvey Harrison wrote:
> On Wed, Mar 6, 2013 at 4:32 PM, Viresh Kumar wrote:
>
>> clk[cluster] = clk_get_sys(name, NULL);
>> - if (!IS_ERR(clk[cluster])) {
>> + if (!IS_ERR_OR_NULL(clk[cluster])) {
>> pr_debug("%s: clk: %p & freq table: %p, cluster: %d\n",
>> __func__, clk[cluster], freq_table[cluster],
>> cluster);
>
>
> You seem pretty attached to IS_ERR_OR_NULL here.
Haha. Not really. I just wanted to get more logical conclusion out. Please check
the other mail (where i would reply to Russell), which might have more
discussion
around this.
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Thu, Mar 07, 2013 at 08:32:37AM +0800, Viresh Kumar wrote:
> On 5 March 2013 18:52, Russell King - ARM Linux
> wrote:
> > On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
> >> + clk[cluster] = clk_get(NULL, name);
> >> + if (!IS_ERR_OR_NULL(clk[cluster])) {
> >
> > NAK. Two reasons.
> >
> > 1. IS_ERR_OR_NULL. You know about this, it's been on the list several
> >times.
>
> Hey, i had a second thought about this one and i have some other opinion
> here. This is a cpufreq driver and we need clock support for sure here, we
> can't work without it. And so here is the latest fixup:
NAK. You just don't understand.
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Wed, Mar 6, 2013 at 4:32 PM, Viresh Kumar wrote:
> clk[cluster] = clk_get_sys(name, NULL);
> - if (!IS_ERR(clk[cluster])) {
> + if (!IS_ERR_OR_NULL(clk[cluster])) {
> pr_debug("%s: clk: %p & freq table: %p, cluster: %d\n",
> __func__, clk[cluster], freq_table[cluster],
> cluster);
You seem pretty attached to IS_ERR_OR_NULL here.
Harvey
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 5 March 2013 18:52, Russell King - ARM Linux wrote:
> On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
>> + clk[cluster] = clk_get(NULL, name);
>> + if (!IS_ERR_OR_NULL(clk[cluster])) {
>
> NAK. Two reasons.
>
> 1. IS_ERR_OR_NULL. You know about this, it's been on the list several
>times.
Hey, i had a second thought about this one and i have some other opinion
here. This is a cpufreq driver and we need clock support for sure here, we
can't work without it. And so here is the latest fixup:
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index fdf54a9..87b7e48 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -9,8 +9,7 @@ config ARM_BIG_LITTLE_CPUFREQ
config ARM_DT_BL_CPUFREQ
tristate "Generic ARM big LITTLE CPUfreq driver probed via DT"
select ARM_BIG_LITTLE_CPUFREQ
- depends on OF
- default n
+ depends on OF && HAVE_CLK
help
This enables the Generic CPUfreq driver for ARM big.LITTLE platform.
This gets frequency tables from DT.
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 2486b9a..d1fdc65 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -147,7 +147,7 @@ static void put_cluster_clk_and_freq_table(u32 cluster)
static int get_cluster_clk_and_freq_table(u32 cluster)
{
- char name[9] = "cluster";
+ char name[9] = "cpu-cluster";
int count;
if (atomic_inc_return(&cluster_usage[cluster]) != 1)
@@ -159,7 +159,7 @@ static int get_cluster_clk_and_freq_table(u32 cluster)
name[7] = cluster + '0';
clk[cluster] = clk_get_sys(name, NULL);
- if (!IS_ERR(clk[cluster])) {
+ if (!IS_ERR_OR_NULL(clk[cluster])) {
pr_debug("%s: clk: %p & freq table: %p, cluster: %d\n",
__func__, clk[cluster], freq_table[cluster],
cluster);
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 7 March 2013 01:25, Russell King - ARM Linux wrote: > On Wed, Mar 06, 2013 at 12:38:36AM +0800, Viresh Kumar wrote: >> So how does below fix look to you? > > Much better, but I think you want a better device name than just "clusterN". I will try to find some other name, maybe cpu-cluster (as what you suggested initially). > Also, please get rid of that "default n" - n is the default default default > default default default there's no need to specify it. :) Ok :) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Wed, Mar 06, 2013 at 12:38:36AM +0800, Viresh Kumar wrote: > So how does below fix look to you? Much better, but I think you want a better device name than just "clusterN". Also, please get rid of that "default n" - n is the default default default default default default there's no need to specify it. :) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On 5 March 2013 18:52, Russell King - ARM Linux wrote:
> On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
>> +static void put_cluster_clk_and_freq_table(u32 cluster)
>> +{
>> + if (!atomic_dec_return(&cluster_usage[cluster])) {
>> + clk_put(clk[cluster]);
>> + clk[cluster] = NULL;
>
> What's the point in setting the clk to NULL?
I couldn't find one and the same is true for freq_table[] too.
>> +static int get_cluster_clk_and_freq_table(u32 cluster)
>> +{
>> + char name[9] = "cluster";
>> + int count;
>> +
>> + if (atomic_inc_return(&cluster_usage[cluster]) != 1)
>> + return 0;
>> +
>> + freq_table[cluster] = arm_bL_ops->get_freq_tbl(cluster, &count);
>> + if (!freq_table[cluster])
>> + goto atomic_dec;
>> +
>> + name[7] = cluster + '0';
>> + clk[cluster] = clk_get(NULL, name);
>> + if (!IS_ERR_OR_NULL(clk[cluster])) {
>
> NAK. Two reasons.
>
> 1. IS_ERR_OR_NULL. You know about this, it's been on the list several
>times.
AAHH .. How can i mess up with this concept.. I am really feeling bad now.
> 2. Maybe clk_get_sys() rather than clk_get() and use a sensible device
>name ("cpu-cluster.%u" maybe) rather than a connection name with a
>NULL device?
That's a good comment (rather than pointing at some stupid mistake), I will
probably keep the same name for the device as well.
So how does below fix look to you?
--x-x-
diff --git a/drivers/cpufreq/arm_big_little.c b/drivers/cpufreq/arm_big_little.c
index 0d6de0e..2486b9a 100644
--- a/drivers/cpufreq/arm_big_little.c
+++ b/drivers/cpufreq/arm_big_little.c
@@ -140,9 +140,7 @@ static void put_cluster_clk_and_freq_table(u32 cluster)
{
if (!atomic_dec_return(&cluster_usage[cluster])) {
clk_put(clk[cluster]);
- clk[cluster] = NULL;
arm_bL_ops->put_freq_tbl(cluster);
- freq_table[cluster] = NULL;
pr_debug("%s: cluster: %d\n", __func__, cluster);
}
}
@@ -160,8 +158,8 @@ static int get_cluster_clk_and_freq_table(u32 cluster)
goto atomic_dec;
name[7] = cluster + '0';
- clk[cluster] = clk_get(NULL, name);
- if (!IS_ERR_OR_NULL(clk[cluster])) {
+ clk[cluster] = clk_get_sys(name, NULL);
+ if (!IS_ERR(clk[cluster])) {
pr_debug("%s: clk: %p & freq table: %p, cluster: %d\n",
__func__, clk[cluster], freq_table[cluster],
cluster);
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Re: [PATCH] cpufreq: ARM big LITTLE: Add generic cpufreq driver and its DT glue
On Tue, Mar 05, 2013 at 12:52:41PM +0800, Viresh Kumar wrote:
> +static void put_cluster_clk_and_freq_table(u32 cluster)
> +{
> + if (!atomic_dec_return(&cluster_usage[cluster])) {
> + clk_put(clk[cluster]);
> + clk[cluster] = NULL;
What's the point in setting the clk to NULL?
> +static int get_cluster_clk_and_freq_table(u32 cluster)
> +{
> + char name[9] = "cluster";
> + int count;
> +
> + if (atomic_inc_return(&cluster_usage[cluster]) != 1)
> + return 0;
> +
> + freq_table[cluster] = arm_bL_ops->get_freq_tbl(cluster, &count);
> + if (!freq_table[cluster])
> + goto atomic_dec;
> +
> + name[7] = cluster + '0';
> + clk[cluster] = clk_get(NULL, name);
> + if (!IS_ERR_OR_NULL(clk[cluster])) {
NAK. Two reasons.
1. IS_ERR_OR_NULL. You know about this, it's been on the list several
times.
2. Maybe clk_get_sys() rather than clk_get() and use a sensible device
name ("cpu-cluster.%u" maybe) rather than a connection name with a
NULL device?
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