[PATCH 0/3] reset: microchip-sparx5: fix the broken switch reset

[PATCH 0/3] reset: microchip-sparx5: fix the broken switch reset

[Michael Walle]

The reset which is used by the switch to reset the switch core has many
different side effects. It is not just a switch reset. Thus don't treat it
as one, but just issue the reset early during boot.

Michael Walle (3):
  reset: microchip-sparx5: issue a reset on startup
  dt-bindings: net: sparx5: don't require a reset line
  net: lan966x: make reset optional

 .../bindings/net/microchip,sparx5-switch.yaml |  2 --
 .../ethernet/microchip/lan966x/lan966x_main.c |  3 ++-
 drivers/reset/reset-microchip-sparx5.c        | 22 ++++++++++++++-----
 3 files changed, 19 insertions(+), 8 deletions(-)

-- 
2.30.2

[PATCH 1/3] reset: microchip-sparx5: issue a reset on startup

[Michael Walle]

Originally this was used in by the switch core driver to issue a reset.
But it turns out, this isn't just a switch core reset but instead it
will reset almost the complete SoC.

Instead of adding almost all devices of the SoC a shared reset line,
issue the reset once early on startup. Keep the reset controller for
backwards compatibility, but make the actual reset a noop.

Suggested-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/reset/reset-microchip-sparx5.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/drivers/reset/reset-microchip-sparx5.c b/drivers/reset/reset-microchip-sparx5.c
index 00b612a0effa..f3528dd1d084 100644
--- a/drivers/reset/reset-microchip-sparx5.c
+++ b/drivers/reset/reset-microchip-sparx5.c
@@ -33,11 +33,8 @@ static struct regmap_config sparx5_reset_regmap_config = {
 	.reg_stride	= 4,
 };
 
-static int sparx5_switch_reset(struct reset_controller_dev *rcdev,
-			       unsigned long id)
+static int sparx5_switch_reset(struct mchp_reset_context *ctx)
 {
-	struct mchp_reset_context *ctx =
-		container_of(rcdev, struct mchp_reset_context, rcdev);
 	u32 val;
 
 	/* Make sure the core is PROTECTED from reset */
@@ -54,8 +51,14 @@ static int sparx5_switch_reset(struct reset_controller_dev *rcdev,
 					1, 100);
 }
 
+static int sparx5_reset_noop(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	return 0;
+}
+
 static const struct reset_control_ops sparx5_reset_ops = {
-	.reset = sparx5_switch_reset,
+	.reset = sparx5_reset_noop,
 };
 
 static int mchp_sparx5_map_syscon(struct platform_device *pdev, char *name,
@@ -122,6 +125,11 @@ static int mchp_sparx5_reset_probe(struct platform_device *pdev)
 	ctx->rcdev.of_node = dn;
 	ctx->props = device_get_match_data(&pdev->dev);
 
+	/* Issue the reset very early, our actual reset callback is a noop. */
+	err = sparx5_switch_reset(ctx);
+	if (err)
+		return err;
+
 	return devm_reset_controller_register(&pdev->dev, &ctx->rcdev);
 }
 
@@ -163,6 +171,10 @@ static int __init mchp_sparx5_reset_init(void)
 	return platform_driver_register(&mchp_sparx5_reset_driver);
 }
 
+/*
+ * Because this is a global reset, keep this postcore_initcall() to issue the
+ * reset as early as possible during the kernel startup.
+ */
 postcore_initcall(mchp_sparx5_reset_init);
 
 MODULE_DESCRIPTION("Microchip Sparx5 switch reset driver");
-- 
2.30.2

Re: [PATCH 1/3] reset: microchip-sparx5: issue a reset on startup

[Steen Hegelund]

Hi Michael,

On Fri, 2022-08-26 at 13:56 +0200, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Originally this was used in by the switch core driver to issue a reset.
> But it turns out, this isn't just a switch core reset but instead it
> will reset almost the complete SoC.
> 
> Instead of adding almost all devices of the SoC a shared reset line,
> issue the reset once early on startup. Keep the reset controller for
> backwards compatibility, but make the actual reset a noop.
> 
> Suggested-by: Philipp Zabel <p.zabel@pengutronix.de>
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
>  drivers/reset/reset-microchip-sparx5.c | 22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/reset/reset-microchip-sparx5.c b/drivers/reset/reset-microchip-sparx5.c
> index 00b612a0effa..f3528dd1d084 100644
> --- a/drivers/reset/reset-microchip-sparx5.c
> +++ b/drivers/reset/reset-microchip-sparx5.c
> @@ -33,11 +33,8 @@ static struct regmap_config sparx5_reset_regmap_config = {
>         .reg_stride     = 4,
>  };
> 
> -static int sparx5_switch_reset(struct reset_controller_dev *rcdev,
> -                              unsigned long id)
> +static int sparx5_switch_reset(struct mchp_reset_context *ctx)
>  {
> -       struct mchp_reset_context *ctx =
> -               container_of(rcdev, struct mchp_reset_context, rcdev);
>         u32 val;
> 
>         /* Make sure the core is PROTECTED from reset */
> @@ -54,8 +51,14 @@ static int sparx5_switch_reset(struct reset_controller_dev *rcdev,
>                                         1, 100);
>  }
> 
> +static int sparx5_reset_noop(struct reset_controller_dev *rcdev,
> +                            unsigned long id)
> +{
> +       return 0;
> +}
> +
>  static const struct reset_control_ops sparx5_reset_ops = {
> -       .reset = sparx5_switch_reset,
> +       .reset = sparx5_reset_noop,
>  };
> 
>  static int mchp_sparx5_map_syscon(struct platform_device *pdev, char *name,
> @@ -122,6 +125,11 @@ static int mchp_sparx5_reset_probe(struct platform_device *pdev)
>         ctx->rcdev.of_node = dn;
>         ctx->props = device_get_match_data(&pdev->dev);
> 
> +       /* Issue the reset very early, our actual reset callback is a noop. */
> +       err = sparx5_switch_reset(ctx);
> +       if (err)
> +               return err;
> +
>         return devm_reset_controller_register(&pdev->dev, &ctx->rcdev);
>  }
> 
> @@ -163,6 +171,10 @@ static int __init mchp_sparx5_reset_init(void)
>         return platform_driver_register(&mchp_sparx5_reset_driver);
>  }
> 
> +/*
> + * Because this is a global reset, keep this postcore_initcall() to issue the
> + * reset as early as possible during the kernel startup.
> + */
>  postcore_initcall(mchp_sparx5_reset_init);
> 
>  MODULE_DESCRIPTION("Microchip Sparx5 switch reset driver");
> --
> 2.30.2
> 

Tested-by: Steen Hegelund <Steen.Hegelund@microchip.com> on Sparx5

BR
Steen

Re: [PATCH 1/3] reset: microchip-sparx5: issue a reset on startup

[Michael Walle]

Hi Steen,

Am 2022-08-29 11:14, schrieb Steen Hegelund:
> On Fri, 2022-08-26 at 13:56 +0200, Michael Walle wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know 
>> the content is safe
>> 
>> Originally this was used in by the switch core driver to issue a 
>> reset.
>> But it turns out, this isn't just a switch core reset but instead it
>> will reset almost the complete SoC.
>> 
>> Instead of adding almost all devices of the SoC a shared reset line,
>> issue the reset once early on startup. Keep the reset controller for
>> backwards compatibility, but make the actual reset a noop.
>> 
>> Suggested-by: Philipp Zabel <p.zabel@pengutronix.de>
>> Signed-off-by: Michael Walle <michael@walle.cc>
..

> Tested-by: Steen Hegelund <Steen.Hegelund@microchip.com> on Sparx5

Thanks for testing!

-michael

Re: [PATCH 1/3] reset: microchip-sparx5: issue a reset on startup

[Philipp Zabel]

On Fr, 2022-08-26 at 13:56 +0200, Michael Walle wrote:
> Originally this was used in by the switch core driver to issue a reset.
> But it turns out, this isn't just a switch core reset but instead it
> will reset almost the complete SoC.
> 
> Instead of adding almost all devices of the SoC a shared reset line,
> issue the reset once early on startup. Keep the reset controller for
> backwards compatibility, but make the actual reset a noop.
> 
> Suggested-by: Philipp Zabel <p.zabel@pengutronix.de>
> Signed-off-by: Michael Walle <michael@walle.cc>

I've applied this patch to the reset/fixes branch.

regards
Philipp

[PATCH 2/3] dt-bindings: net: sparx5: don't require a reset line

[Michael Walle]

Make the reset line optional. It turns out, there is no dedicated reset
for the switch. Instead, the reset which was used up until now, was kind
of a global reset. This is now handled elsewhere, thus don't require a
reset.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 .../devicetree/bindings/net/microchip,sparx5-switch.yaml        | 2 --
 1 file changed, 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/microchip,sparx5-switch.yaml b/Documentation/devicetree/bindings/net/microchip,sparx5-switch.yaml
index 6c86d3d85e99..4a959639eb08 100644
--- a/Documentation/devicetree/bindings/net/microchip,sparx5-switch.yaml
+++ b/Documentation/devicetree/bindings/net/microchip,sparx5-switch.yaml
@@ -144,8 +144,6 @@ required:
   - reg-names
   - interrupts
   - interrupt-names
-  - resets
-  - reset-names
   - ethernet-ports
 
 additionalProperties: false
-- 
2.30.2

Re: [PATCH 2/3] dt-bindings: net: sparx5: don't require a reset line

[Krzysztof Kozlowski]

On 26/08/2022 14:56, Michael Walle wrote:
> Make the reset line optional. It turns out, there is no dedicated reset
> for the switch. Instead, the reset which was used up until now, was kind
> of a global reset. This is now handled elsewhere, thus don't require a
> reset.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>


Best regards,
Krzysztof

[PATCH 3/3] net: lan966x: make reset optional

[Michael Walle]

There is no dedicated reset for just the switch core. The reset which
is used up until now, is more of a global reset, resetting almost the
whole SoC and cause spurious errors by doing so. Make it possible to
handle the reset elsewhere and mark the reset as optional.

Signed-off-by: Michael Walle <michael@walle.cc>
---
 drivers/net/ethernet/microchip/lan966x/lan966x_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
index 2ad078608c45..e2c77f954a3d 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
@@ -971,7 +971,8 @@ static int lan966x_reset_switch(struct lan966x *lan966x)
 	int val = 0;
 	int ret;
 
-	switch_reset = devm_reset_control_get_shared(lan966x->dev, "switch");
+	switch_reset = devm_reset_control_get_optional_shared(lan966x->dev,
+							      "switch");
 	if (IS_ERR(switch_reset))
 		return dev_err_probe(lan966x->dev, PTR_ERR(switch_reset),
 				     "Could not obtain switch reset");
-- 
2.30.2

Re: [PATCH 0/3] reset: microchip-sparx5: fix the broken switch reset

[Michael Walle]

Am 2022-08-26 13:56, schrieb Michael Walle:
> The reset which is used by the switch to reset the switch core has many
> different side effects. It is not just a switch reset. Thus don't treat 
> it
> as one, but just issue the reset early during boot.
> 
> Michael Walle (3):
>   reset: microchip-sparx5: issue a reset on startup
>   dt-bindings: net: sparx5: don't require a reset line
>   net: lan966x: make reset optional
> 
>  .../bindings/net/microchip,sparx5-switch.yaml |  2 --
>  .../ethernet/microchip/lan966x/lan966x_main.c |  3 ++-
>  drivers/reset/reset-microchip-sparx5.c        | 22 ++++++++++++++-----
>  3 files changed, 19 insertions(+), 8 deletions(-)

Philipp, you could just patch #1, I guess. I'd then
resend patches #2 and #3 to the netdev ML targetting net-next.
As long as the device tree itself isn't changed, there should
be no dependency between these two.

-michael