[PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted

[PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted

[Sudeep Holla]

Instead of relying on the firmware to keep the clock rates sorted, let
us sort the list. This is not essential for clock layer but it helps
to find the min and max rates easily from the list.

Fixes: 5f6c6430e904 ("firmware: arm_scmi: add initial support for clock protocol")
Reported-by: Dien Pham <dien.pham.ry@renesas.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/firmware/arm_scmi/clock.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

Hi Dien-san,

If you could review/test these patches, I can queue them ASAP.
I am planning to send the PR for ARM SoC later this week, so I need
your tested-by.

Regards,
Sudeep

diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index 4c2227662b26..2dd119cdebf6 100644
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -5,6 +5,8 @@
  * Copyright (C) 2018 ARM Ltd.
  */

+#include <linux/sort.h>
+
 #include "common.h"

 enum scmi_clock_protocol_cmd {
@@ -121,6 +123,13 @@ static int scmi_clock_attributes_get(const struct scmi_handle *handle,
 	return ret;
 }

+static int rate_cmp_func(const void *_r1, const void *_r2)
+{
+	u64 *r1 = _r1, *r2 = _r2;
+
+	return r1 - r2;
+}
+
 static int
 scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
 			      struct scmi_clock_info *clk)
@@ -184,8 +193,10 @@ scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
 		 */
 	} while (num_returned && num_remaining);

-	if (rate_discrete)
+	if (rate_discrete) {
 		clk->list.num_rates = tot_rate_cnt;
+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
+	}

 	clk->rate_discrete = rate_discrete;

--
2.17.1

[PATCH 2/2] clk: scmi: Fix min and max rate when registering clocks with discrete rates

[Sudeep Holla]

Currently we are not initializing the scmi clock with discrete rates
correctly. We fetch the min_rate and max_rate value only for clocks with
ranges and ignore the ones with discrete rates. This will lead to wrong
initialization of rate range when clock supports discrete rate.

Fix this by using the first and the last rate in the sorted list of the
discrete clock rates while registering the clock.

Fixes: 6d6a1d82eaef7 ("clk: add support for clocks provided by SCMI")
Reported-by: Dien Pham <dien.pham.ry@renesas.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
---
 drivers/clk/clk-scmi.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

Hi Stephen,

If you fine, I can take this via ARM SoC along with the change in firmware
driver. But it is fine if you want to merge this independently as it should
be fine. Let me know either way.

Regards,
Sudeep

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index c491f5de0f3f..ea65b7bf1408 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -103,6 +103,8 @@ static const struct clk_ops scmi_clk_ops = {
 static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
 {
 	int ret;
+	unsigned long min_rate, max_rate;
+
 	struct clk_init_data init = {
 		.flags = CLK_GET_RATE_NOCACHE,
 		.num_parents = 0,
@@ -112,9 +114,23 @@ static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)

 	sclk->hw.init = &init;
 	ret = devm_clk_hw_register(dev, &sclk->hw);
-	if (!ret)
-		clk_hw_set_rate_range(&sclk->hw, sclk->info->range.min_rate,
-				      sclk->info->range.max_rate);
+	if (ret)
+		return ret;
+
+	if (sclk->info->rate_discrete) {
+		int num_rates = sclk->info->list.num_rates;
+
+		if (num_rates <= 0)
+			return -EINVAL;
+
+		min_rate = sclk->info->list.rates[0]
+		max_rate = sclk->info->list.rates[num_rates - 1];
+	} else {
+		min_rate = sclk->info->range.min_rate;
+		max_rate = sclk->info->range.max_rate;
+	}
+
+	clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate);
 	return ret;
 }

--
2.17.1

Re: [PATCH 2/2] clk: scmi: Fix min and max rate when registering clocks with discrete rates

[Sudeep Holla]

On Wed, Jul 08, 2020 at 12:07:25PM +0100, Sudeep Holla wrote:
> Currently we are not initializing the scmi clock with discrete rates
> correctly. We fetch the min_rate and max_rate value only for clocks with
> ranges and ignore the ones with discrete rates. This will lead to wrong
> initialization of rate range when clock supports discrete rate.
> 
> Fix this by using the first and the last rate in the sorted list of the
> discrete clock rates while registering the clock.
> 
> Fixes: 6d6a1d82eaef7 ("clk: add support for clocks provided by SCMI")
> Reported-by: Dien Pham <dien.pham.ry@renesas.com>
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  drivers/clk/clk-scmi.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> Hi Stephen,
> 
> If you fine, I can take this via ARM SoC along with the change in firmware
> driver. But it is fine if you want to merge this independently as it should
> be fine. Let me know either way.
> 
> Regards,
> Sudeep
> 
> diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
> index c491f5de0f3f..ea65b7bf1408 100644
> --- a/drivers/clk/clk-scmi.c
> +++ b/drivers/clk/clk-scmi.c
> @@ -103,6 +103,8 @@ static const struct clk_ops scmi_clk_ops = {
>  static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
>  {
>  	int ret;
> +	unsigned long min_rate, max_rate;
> +
>  	struct clk_init_data init = {
>  		.flags = CLK_GET_RATE_NOCACHE,
>  		.num_parents = 0,
> @@ -112,9 +114,23 @@ static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
> 
>  	sclk->hw.init = &init;
>  	ret = devm_clk_hw_register(dev, &sclk->hw);
> -	if (!ret)
> -		clk_hw_set_rate_range(&sclk->hw, sclk->info->range.min_rate,
> -				      sclk->info->range.max_rate);
> +	if (ret)
> +		return ret;
> +
> +	if (sclk->info->rate_discrete) {
> +		int num_rates = sclk->info->list.num_rates;
> +
> +		if (num_rates <= 0)
> +			return -EINVAL;
> +
> +		min_rate = sclk->info->list.rates[0]

I seem to have sent a version with ; missing above though I fixed but
sent the old stale version as I had written a note to you 🙁 

-- 
Regards,
Sudeep

RE: [PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted

[Dien Pham]

Hi Sudeep,

I share my build warning and some in-line comment below:

  CC      drivers/firmware/arm_scmi/clock.o
drivers/firmware/arm_scmi/clock.c: In function 'rate_cmp_func':
drivers/firmware/arm_scmi/clock.c:127:12: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  u64 *r1 = _r1, *r2 = _r2;
            ^~~
drivers/firmware/arm_scmi/clock.c:127:23: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
  u64 *r1 = _r1, *r2 = _r2;
                       ^~~
  CC      arch/arm64/kernel/vdso.o
drivers/firmware/arm_scmi/clock.c: In function 'scmi_clock_protocol_init':
drivers/firmware/arm_scmi/clock.c:197:3: warning: 'rate' may be used uninitialized in this function [-Wmaybe-uninitialized]
   sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

>-----Original Message-----
>From: Sudeep Holla <sudeep.holla@arm.com> 
>Sent: Wednesday, July 8, 2020 6:07 PM
>To: linux-arm-kernel@lists.infradead.org; linux-clk@vger.kernel.org; Stephen Boyd <sboyd@kernel.org>
>Cc: Sudeep Holla <sudeep.holla@arm.com>; linux-kernel@vger.kernel.org; Michael Turquette <mturquette@baylibre.com>; Dien Pham <dien.pham.ry@renesas.com>
>Subject: [PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted
>
>Instead of relying on the firmware to keep the clock rates sorted, let us sort the list. This is not essential for clock layer but it helps to find the min and max rates easily from the list.
>
>Fixes: 5f6c6430e904 ("firmware: arm_scmi: add initial support for clock protocol")
>Reported-by: Dien Pham <dien.pham.ry@renesas.com>
>Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
>---
> drivers/firmware/arm_scmi/clock.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
>Hi Dien-san,
>
>If you could review/test these patches, I can queue them ASAP.
>I am planning to send the PR for ARM SoC later this week, so I need your tested-by.

I applied the patch,
Although there are some build warnings, but the patch effect is ok.

>
>Regards,
>Sudeep
>
>diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
>index 4c2227662b26..2dd119cdebf6 100644
>--- a/drivers/firmware/arm_scmi/clock.c
>+++ b/drivers/firmware/arm_scmi/clock.c
>@@ -5,6 +5,8 @@
>  * Copyright (C) 2018 ARM Ltd.
>  */
>
>+#include <linux/sort.h>
>+
> #include "common.h"
>
> enum scmi_clock_protocol_cmd {
>@@ -121,6 +123,13 @@ static int scmi_clock_attributes_get(const struct scmi_handle *handle,
> 	return ret;
> }
>
>+static int rate_cmp_func(const void *_r1, const void *_r2) {
>+	u64 *r1 = _r1, *r2 = _r2;

It is better to add 'const' as below to avoid warning.
const u64 *r1 = _r1, *r2 = _r2;

>+
>+	return r1 - r2;

r1 and r2 are u64, but returned value is 'int' type.
Do you think we should improve this ? e.g. return (int)r1 - r2;

>+}
>+
> static int
> scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> 			      struct scmi_clock_info *clk)
>@@ -184,8 +193,10 @@ scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> 		 */
> 	} while (num_returned && num_remaining);
>
>-	if (rate_discrete)
>+	if (rate_discrete) {
> 		clk->list.num_rates = tot_rate_cnt;
>+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);

About warning of above line, I think it relates to below snip of code:
                if (tot_rate_cnt + num_returned > SCMI_MAX_NUM_RATES) {
                        dev_err(handle->dev, "No. of rates > MAX_NUM_RATES");
                        break;
                }

I see that in this case is true, it is not proceeded as error case,
If so I think you can update 'rate' for value from 'tot_rate_cnt' to SCMI_MAX_NUM_RATES at here.
How do you think ?

>+	}
>
> 	clk->rate_discrete = rate_discrete;
>
>--
>2.17.1

Best regard.
DIEN Pham

Re: [PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted

[Sudeep Holla]

Hi Dien-san,

On Thu, Jul 09, 2020 at 08:20:51AM +0000, Dien Pham wrote:
> Hi Sudeep,
>
> I share my build warning and some in-line comment below:
>
>   CC      drivers/firmware/arm_scmi/clock.o
> drivers/firmware/arm_scmi/clock.c: In function 'rate_cmp_func':
> drivers/firmware/arm_scmi/clock.c:127:12: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
>   u64 *r1 = _r1, *r2 = _r2;
>             ^~~
> drivers/firmware/arm_scmi/clock.c:127:23: warning: initialization discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
>   u64 *r1 = _r1, *r2 = _r2;
>                        ^~~
>   CC      arch/arm64/kernel/vdso.o
> drivers/firmware/arm_scmi/clock.c: In function 'scmi_clock_protocol_init':
> drivers/firmware/arm_scmi/clock.c:197:3: warning: 'rate' may be used uninitialized in this function [-Wmaybe-uninitialized]
>    sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>

Sorry for this. I noticed yesterday when I built but strangely I had
created patches before I fixed these and sent them instead of fixed version.
My mistake.

> >-----Original Message-----
> >From: Sudeep Holla <sudeep.holla@arm.com>
> >Sent: Wednesday, July 8, 2020 6:07 PM
> >To: linux-arm-kernel@lists.infradead.org; linux-clk@vger.kernel.org; Stephen Boyd <sboyd@kernel.org>
> >Cc: Sudeep Holla <sudeep.holla@arm.com>; linux-kernel@vger.kernel.org; Michael Turquette <mturquette@baylibre.com>; Dien Pham <dien.pham.ry@renesas.com>
> >Subject: [PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted
> >
> >Instead of relying on the firmware to keep the clock rates sorted, let us sort the list. This is not essential for clock layer but it helps to find the min and max rates easily from the list.
> >
> >Fixes: 5f6c6430e904 ("firmware: arm_scmi: add initial support for clock protocol")
> >Reported-by: Dien Pham <dien.pham.ry@renesas.com>
> >Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> >---
> > drivers/firmware/arm_scmi/clock.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
> >Hi Dien-san,
> >
> >If you could review/test these patches, I can queue them ASAP.
> >I am planning to send the PR for ARM SoC later this week, so I need your tested-by.
>
> I applied the patch,
> Although there are some build warnings, but the patch effect is ok.
>

Thanks for testing.

> >
> >Regards,
> >Sudeep
> >
> >diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
> >index 4c2227662b26..2dd119cdebf6 100644
> >--- a/drivers/firmware/arm_scmi/clock.c
> >+++ b/drivers/firmware/arm_scmi/clock.c
> >@@ -5,6 +5,8 @@
> >  * Copyright (C) 2018 ARM Ltd.
> >  */
> >
> >+#include <linux/sort.h>
> >+
> > #include "common.h"
> >
> > enum scmi_clock_protocol_cmd {
> >@@ -121,6 +123,13 @@ static int scmi_clock_attributes_get(const struct scmi_handle *handle,
> > 	return ret;
> > }
> >
> >+static int rate_cmp_func(const void *_r1, const void *_r2) {
> >+	u64 *r1 = _r1, *r2 = _r2;
>
> It is better to add 'const' as below to avoid warning.
> const u64 *r1 = _r1, *r2 = _r2;
>

Yes, I have this in the correct version which I sent as v2 this morning.

> >+
> >+	return r1 - r2;
>
> r1 and r2 are u64, but returned value is 'int' type.
> Do you think we should improve this ? e.g. return (int)r1 - r2;
>

Not changing to const above must suffice.

> >+}
> >+
> > static int
> > scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> > 			      struct scmi_clock_info *clk)
> >@@ -184,8 +193,10 @@ scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> > 		 */
> > 	} while (num_returned && num_remaining);
> >
> >-	if (rate_discrete)
> >+	if (rate_discrete) {
> > 		clk->list.num_rates = tot_rate_cnt;
> >+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
>
> About warning of above line, I think it relates to below snip of code:
>                 if (tot_rate_cnt + num_returned > SCMI_MAX_NUM_RATES) {
>                         dev_err(handle->dev, "No. of rates > MAX_NUM_RATES");
>                         break;
>                 }
>

I don't understand your comment and relation to above warning.

> I see that in this case is true, it is not proceeded as error case,
> If so I think you can update 'rate' for value from 'tot_rate_cnt' to SCMI_MAX_NUM_RATES at here.
> How do you think ?
>

--
Regards,
Sudeep

RE: [PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted

[Dien Pham]

Dear Sudeep-san,

> > >+}
> > >+
> > > static int
> > > scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> > > 			      struct scmi_clock_info *clk) @@ -184,8 +193,10 @@ 
> > >scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> > > 		 */
> > > 	} while (num_returned && num_remaining);
> > >
> > >-	if (rate_discrete)
> > >+	if (rate_discrete) {
> > > 		clk->list.num_rates = tot_rate_cnt;
> > >+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
> >
> > About warning of above line, I think it relates to below snip of code:
> >                 if (tot_rate_cnt + num_returned > SCMI_MAX_NUM_RATES) {
> >                         dev_err(handle->dev, "No. of rates > MAX_NUM_RATES");
> >                         break;
> >                 }
> >
> 
> I don't understand your comment and relation to above warning.

I'd like to mention about below warning.

>drivers/firmware/arm_scmi/clock.c: In function 'scmi_clock_protocol_init':
>drivers/firmware/arm_scmi/clock.c:197:3: warning: 'rate' may be used uninitialized in this function [-Wmaybe-uninitialized]
>  sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);

The warning for line
> > >+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);

But, I think that it is affected by 'break' of below line. And for fixing this warning, I think we should fix inside this 'if' block.
> >                 if (tot_rate_cnt + num_returned > SCMI_MAX_NUM_RATES) {
> >                         dev_err(handle->dev, "No. of rates > MAX_NUM_RATES");
> >                         break;
> >                 }

Best regard,
DIEN Pham

Re: [PATCH 1/2] firmware: arm_scmi: Keep the discrete clock rates sorted

[Sudeep Holla]

On Thu, Jul 09, 2020 at 08:53:44AM +0000, Dien Pham wrote:
> Dear Sudeep-san,
> 
> > > >+}
> > > >+
> > > > static int
> > > > scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> > > > 			      struct scmi_clock_info *clk) @@ -184,8 +193,10 @@ 
> > > >scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
> > > > 		 */
> > > > 	} while (num_returned && num_remaining);
> > > >
> > > >-	if (rate_discrete)
> > > >+	if (rate_discrete) {
> > > > 		clk->list.num_rates = tot_rate_cnt;
> > > >+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
> > >
> > > About warning of above line, I think it relates to below snip of code:
> > >                 if (tot_rate_cnt + num_returned > SCMI_MAX_NUM_RATES) {
> > >                         dev_err(handle->dev, "No. of rates > MAX_NUM_RATES");
> > >                         break;
> > >                 }
> > >
> > 
> > I don't understand your comment and relation to above warning.
> 
> I'd like to mention about below warning.
> 
> >drivers/firmware/arm_scmi/clock.c: In function 'scmi_clock_protocol_init':
> >drivers/firmware/arm_scmi/clock.c:197:3: warning: 'rate' may be used uninitialized in this function [-Wmaybe-uninitialized]

Ah ok, sorry I didn't see this one. I am unable to observe this in the
default build, I will check with W=1. Thanks for that.

> >  sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
> 
> The warning for line
> > > >+		sort(rate, tot_rate_cnt, sizeof(*rate), rate_cmp_func, NULL);
> 
> But, I think that it is affected by 'break' of below line. And for fixing
> this warning, I think we should fix inside this 'if' block.

OK will take a look.

-- 
Regards,
Sudeep