[PATCH-for-9.0 v3 0/3] hw/clock: Propagate clock changes when STM32L4X5 MUX is updated

[PATCH-for-9.0 v3 0/3] hw/clock: Propagate clock changes when STM32L4X5 MUX is updated

[Philippe Mathieu-Daudé]

Since v2:
- Simpler approach

Since v1:
- Rework API to only propagate when both clock_set
  and clock_set_mul_div modified the clock params
  (Peter & Luc).
- Use that in zynq_slcr.

Per https://www.qemu.org/docs/master/devel/clocks.html#clock-multiplier-and-divider-settings:

  Note that clock_set_mul_div() does not automatically call
  clock_propagate(). If you make a runtime change to the
  multiplier or divider you must call clock_propagate() yourself.

Fix what we forgot to do that in recent commit ec7d83acbd
("hw/misc/stm32l4x5_rcc: Add an internal clock multiplexer object")

Arnaud Minier (1):
  hw/misc/stm32l4x5_rcc: Propagate period when enabling a clock

Philippe Mathieu-Daudé (2):
  hw/clock: Let clock_set_mul_div() return a boolean value
  hw/misc/stm32l4x5_rcc: Inline clock_update() in clock_mux_update()

 docs/devel/clocks.rst   | 4 ++++
 include/hw/clock.h      | 4 +++-
 hw/core/clock.c         | 8 +++++++-
 hw/misc/stm32l4x5_rcc.c | 9 +++++++--
 4 files changed, 21 insertions(+), 4 deletions(-)

-- 
2.41.0

[PATCH-for-9.0 v3 1/3] hw/clock: Let clock_set_mul_div() return a boolean value

[Philippe Mathieu-Daudé]

Let clock_set_mul_div() return a boolean value whether the
clock has been updated or not, similarly to clock_set().

Return early when clock_set_mul_div() is called with
same mul/div values the clock has.

Acked-by: Luc Michel <luc@lmichel.fr>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 docs/devel/clocks.rst | 4 ++++
 include/hw/clock.h    | 4 +++-
 hw/core/clock.c       | 8 +++++++-
 3 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/docs/devel/clocks.rst b/docs/devel/clocks.rst
index c4d14bde04..b2d1148cdb 100644
--- a/docs/devel/clocks.rst
+++ b/docs/devel/clocks.rst
@@ -279,6 +279,10 @@ You can change the multiplier and divider of a clock at runtime,
 so you can use this to model clock controller devices which
 have guest-programmable frequency multipliers or dividers.
 
+Similary to ``clock_set()``, ``clock_set_mul_div()`` returns ``true`` if
+the clock state was modified; that is, if the multiplier or the diviser
+or both were changed by the call.
+
 Note that ``clock_set_mul_div()`` does not automatically call
 ``clock_propagate()``. If you make a runtime change to the
 multiplier or divider you must call clock_propagate() yourself.
diff --git a/include/hw/clock.h b/include/hw/clock.h
index bb12117f67..eb58599131 100644
--- a/include/hw/clock.h
+++ b/include/hw/clock.h
@@ -357,6 +357,8 @@ char *clock_display_freq(Clock *clk);
  * @multiplier: multiplier value
  * @divider: divider value
  *
+ * @return: true if the clock is changed.
+ *
  * By default, a Clock's children will all run with the same period
  * as their parent. This function allows you to adjust the multiplier
  * and divider used to derive the child clock frequency.
@@ -374,6 +376,6 @@ char *clock_display_freq(Clock *clk);
  * Note that this function does not call clock_propagate(); the
  * caller should do that if necessary.
  */
-void clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider);
+bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider);
 
 #endif /* QEMU_HW_CLOCK_H */
diff --git a/hw/core/clock.c b/hw/core/clock.c
index d82e44cd1a..a19c7db7df 100644
--- a/hw/core/clock.c
+++ b/hw/core/clock.c
@@ -143,14 +143,20 @@ char *clock_display_freq(Clock *clk)
     return freq_to_str(clock_get_hz(clk));
 }
 
-void clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider)
+bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider)
 {
     assert(divider != 0);
 
+    if (clk->multiplier == multiplier && clk->divider == divider) {
+        return false;
+    }
+
     trace_clock_set_mul_div(CLOCK_PATH(clk), clk->multiplier, multiplier,
                             clk->divider, divider);
     clk->multiplier = multiplier;
     clk->divider = divider;
+
+    return true;
 }
 
 static void clock_initfn(Object *obj)
-- 
2.41.0

Re: [PATCH-for-9.0 v3 1/3] hw/clock: Let clock_set_mul_div() return a boolean value

[Alistair Francis]

On Tue, Mar 26, 2024 at 1:29 AM Philippe Mathieu-Daudé
<philmd@linaro.org> wrote:
>
> Let clock_set_mul_div() return a boolean value whether the
> clock has been updated or not, similarly to clock_set().
>
> Return early when clock_set_mul_div() is called with
> same mul/div values the clock has.
>
> Acked-by: Luc Michel <luc@lmichel.fr>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  docs/devel/clocks.rst | 4 ++++
>  include/hw/clock.h    | 4 +++-
>  hw/core/clock.c       | 8 +++++++-
>  3 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/docs/devel/clocks.rst b/docs/devel/clocks.rst
> index c4d14bde04..b2d1148cdb 100644
> --- a/docs/devel/clocks.rst
> +++ b/docs/devel/clocks.rst
> @@ -279,6 +279,10 @@ You can change the multiplier and divider of a clock at runtime,
>  so you can use this to model clock controller devices which
>  have guest-programmable frequency multipliers or dividers.
>
> +Similary to ``clock_set()``, ``clock_set_mul_div()`` returns ``true`` if
> +the clock state was modified; that is, if the multiplier or the diviser
> +or both were changed by the call.
> +
>  Note that ``clock_set_mul_div()`` does not automatically call
>  ``clock_propagate()``. If you make a runtime change to the
>  multiplier or divider you must call clock_propagate() yourself.
> diff --git a/include/hw/clock.h b/include/hw/clock.h
> index bb12117f67..eb58599131 100644
> --- a/include/hw/clock.h
> +++ b/include/hw/clock.h
> @@ -357,6 +357,8 @@ char *clock_display_freq(Clock *clk);
>   * @multiplier: multiplier value
>   * @divider: divider value
>   *
> + * @return: true if the clock is changed.
> + *
>   * By default, a Clock's children will all run with the same period
>   * as their parent. This function allows you to adjust the multiplier
>   * and divider used to derive the child clock frequency.
> @@ -374,6 +376,6 @@ char *clock_display_freq(Clock *clk);
>   * Note that this function does not call clock_propagate(); the
>   * caller should do that if necessary.
>   */
> -void clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider);
> +bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider);
>
>  #endif /* QEMU_HW_CLOCK_H */
> diff --git a/hw/core/clock.c b/hw/core/clock.c
> index d82e44cd1a..a19c7db7df 100644
> --- a/hw/core/clock.c
> +++ b/hw/core/clock.c
> @@ -143,14 +143,20 @@ char *clock_display_freq(Clock *clk)
>      return freq_to_str(clock_get_hz(clk));
>  }
>
> -void clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider)
> +bool clock_set_mul_div(Clock *clk, uint32_t multiplier, uint32_t divider)
>  {
>      assert(divider != 0);
>
> +    if (clk->multiplier == multiplier && clk->divider == divider) {
> +        return false;
> +    }
> +
>      trace_clock_set_mul_div(CLOCK_PATH(clk), clk->multiplier, multiplier,
>                              clk->divider, divider);
>      clk->multiplier = multiplier;
>      clk->divider = divider;
> +
> +    return true;
>  }
>
>  static void clock_initfn(Object *obj)
> --
> 2.41.0
>
>

[PATCH-for-9.0 v3 2/3] hw/misc/stm32l4x5_rcc: Inline clock_update() in clock_mux_update()

[Philippe Mathieu-Daudé]

Trivial inlining in preliminary patch to make the next
one easier to review.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/misc/stm32l4x5_rcc.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/misc/stm32l4x5_rcc.c b/hw/misc/stm32l4x5_rcc.c
index bc2d63528b..49b90afdf0 100644
--- a/hw/misc/stm32l4x5_rcc.c
+++ b/hw/misc/stm32l4x5_rcc.c
@@ -48,6 +48,8 @@ static void clock_mux_update(RccClockMuxState *mux, bool bypass_source)
     uint64_t src_freq;
     Clock *current_source = mux->srcs[mux->src];
     uint32_t freq_multiplier = 0;
+    bool clk_changed = false;
+
     /*
      * To avoid rounding errors, we use the clock period instead of the
      * frequency.
@@ -60,7 +62,10 @@ static void clock_mux_update(RccClockMuxState *mux, bool bypass_source)
     }
 
     clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
-    clock_update(mux->out, clock_get(current_source));
+    clk_changed |= clock_set(mux->out, clock_get(current_source));
+    if (clk_changed) {
+        clock_propagate(mux->out);
+    }
 
     src_freq = clock_get_hz(current_source);
     /* TODO: can we simply detect if the config changed so that we reduce log spam ? */
-- 
2.41.0

Re: [PATCH-for-9.0 v3 2/3] hw/misc/stm32l4x5_rcc: Inline clock_update() in clock_mux_update()

[Alistair Francis]

On Tue, Mar 26, 2024 at 1:29 AM Philippe Mathieu-Daudé
<philmd@linaro.org> wrote:
>
> Trivial inlining in preliminary patch to make the next
> one easier to review.
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  hw/misc/stm32l4x5_rcc.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/hw/misc/stm32l4x5_rcc.c b/hw/misc/stm32l4x5_rcc.c
> index bc2d63528b..49b90afdf0 100644
> --- a/hw/misc/stm32l4x5_rcc.c
> +++ b/hw/misc/stm32l4x5_rcc.c
> @@ -48,6 +48,8 @@ static void clock_mux_update(RccClockMuxState *mux, bool bypass_source)
>      uint64_t src_freq;
>      Clock *current_source = mux->srcs[mux->src];
>      uint32_t freq_multiplier = 0;
> +    bool clk_changed = false;
> +
>      /*
>       * To avoid rounding errors, we use the clock period instead of the
>       * frequency.
> @@ -60,7 +62,10 @@ static void clock_mux_update(RccClockMuxState *mux, bool bypass_source)
>      }
>
>      clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
> -    clock_update(mux->out, clock_get(current_source));
> +    clk_changed |= clock_set(mux->out, clock_get(current_source));
> +    if (clk_changed) {
> +        clock_propagate(mux->out);
> +    }
>
>      src_freq = clock_get_hz(current_source);
>      /* TODO: can we simply detect if the config changed so that we reduce log spam ? */
> --
> 2.41.0
>
>

[PATCH-for-9.0 v3 3/3] hw/misc/stm32l4x5_rcc: Propagate period when enabling a clock

[Philippe Mathieu-Daudé]

From: Arnaud Minier <arnaud.minier@telecom-paris.fr>

The "clock_set_mul_div" function doesn't propagate the clock period
to the children if it is changed (e.g. by enabling/disabling a clock
multiplexer).
This was overlooked during the implementation due to late changes.

This commit propagates the change if the multiplier or divider changes.

Fixes: ec7d83acbd ("hw/misc/stm32l4x5_rcc: Add an internal clock multiplexer object")
Signed-off-by: Arnaud Minier <arnaud.minier@telecom-paris.fr>
Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
Message-ID: <20240317103918.44375-2-arnaud.minier@telecom-paris.fr>
[PMD: Check clock_set_mul_div() return value]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 hw/misc/stm32l4x5_rcc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/misc/stm32l4x5_rcc.c b/hw/misc/stm32l4x5_rcc.c
index 49b90afdf0..ed2dbd9dc3 100644
--- a/hw/misc/stm32l4x5_rcc.c
+++ b/hw/misc/stm32l4x5_rcc.c
@@ -61,7 +61,7 @@ static void clock_mux_update(RccClockMuxState *mux, bool bypass_source)
         freq_multiplier = mux->divider;
     }
 
-    clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
+    clk_changed |= clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
     clk_changed |= clock_set(mux->out, clock_get(current_source));
     if (clk_changed) {
         clock_propagate(mux->out);
-- 
2.41.0

Re: [PATCH-for-9.0 v3 3/3] hw/misc/stm32l4x5_rcc: Propagate period when enabling a clock

[Alistair Francis]

On Tue, Mar 26, 2024 at 1:29 AM Philippe Mathieu-Daudé
<philmd@linaro.org> wrote:
>
> From: Arnaud Minier <arnaud.minier@telecom-paris.fr>
>
> The "clock_set_mul_div" function doesn't propagate the clock period
> to the children if it is changed (e.g. by enabling/disabling a clock
> multiplexer).
> This was overlooked during the implementation due to late changes.
>
> This commit propagates the change if the multiplier or divider changes.
>
> Fixes: ec7d83acbd ("hw/misc/stm32l4x5_rcc: Add an internal clock multiplexer object")
> Signed-off-by: Arnaud Minier <arnaud.minier@telecom-paris.fr>
> Signed-off-by: Inès Varhol <ines.varhol@telecom-paris.fr>
> Message-ID: <20240317103918.44375-2-arnaud.minier@telecom-paris.fr>
> [PMD: Check clock_set_mul_div() return value]
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  hw/misc/stm32l4x5_rcc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/misc/stm32l4x5_rcc.c b/hw/misc/stm32l4x5_rcc.c
> index 49b90afdf0..ed2dbd9dc3 100644
> --- a/hw/misc/stm32l4x5_rcc.c
> +++ b/hw/misc/stm32l4x5_rcc.c
> @@ -61,7 +61,7 @@ static void clock_mux_update(RccClockMuxState *mux, bool bypass_source)
>          freq_multiplier = mux->divider;
>      }
>
> -    clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
> +    clk_changed |= clock_set_mul_div(mux->out, freq_multiplier, mux->multiplier);
>      clk_changed |= clock_set(mux->out, clock_get(current_source));
>      if (clk_changed) {
>          clock_propagate(mux->out);
> --
> 2.41.0
>
>

Re: [PATCH-for-9.0 v3 0/3] hw/clock: Propagate clock changes when STM32L4X5 MUX is updated

[Philippe Mathieu-Daudé]

On 25/3/24 16:28, Philippe Mathieu-Daudé wrote:

> Per https://www.qemu.org/docs/master/devel/clocks.html#clock-multiplier-and-divider-settings:
> 
>    Note that clock_set_mul_div() does not automatically call
>    clock_propagate(). If you make a runtime change to the
>    multiplier or divider you must call clock_propagate() yourself.
> 
> Fix what we forgot to do that in recent commit ec7d83acbd
> ("hw/misc/stm32l4x5_rcc: Add an internal clock multiplexer object")
> 
> Arnaud Minier (1):
>    hw/misc/stm32l4x5_rcc: Propagate period when enabling a clock
> 
> Philippe Mathieu-Daudé (2):
>    hw/clock: Let clock_set_mul_div() return a boolean value
>    hw/misc/stm32l4x5_rcc: Inline clock_update() in clock_mux_update()

Series queued (thanks Alistair!).