[PATCH 0/2] spi: amlogic: meson-spicc: Use pinctrl to drive CLK line when idle

[PATCH 0/2] spi: amlogic: meson-spicc: Use pinctrl to drive CLK line when idle

[Amjad Ouled-Ameur]

Between SPI transactions, all SPI pins are in HiZ state. When using the SS
signal from the SPICC controller it's not an issue because when the
transaction resumes all pins come back to the right state at the same time
as SS.

The problem is when we use CS as a GPIO. In fact, between the GPIO CS
state change and SPI pins state change from idle, you can have a missing or
spurious clock transition.

Set a bias on the clock depending on the clock polarity requested before CS
goes active, by passing a special "idle-low" and "idle-high" pinctrl state
and setting the right state at a start of a message.

Amjad Ouled-Ameur (2):
  spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI
    signal states
  spi: meson-spicc: Use pinctrl to drive CLK line when idle

 .../bindings/spi/amlogic,meson-gx-spicc.yaml  | 15 +++++++
 arch/arm64/boot/dts/amlogic/meson-gxl.dtsi    | 14 +++++++
 drivers/spi/spi-meson-spicc.c                 | 39 ++++++++++++++++++-
 3 files changed, 67 insertions(+), 1 deletion(-)

-- 
2.37.1


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[PATCH 1/2] spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI signal states

[Amjad Ouled-Ameur]

SPI pins of the SPICC Controller in Meson-GX needs to be controlled by
pin biais when idle. Therefore define three pinctrl names:
- default: SPI pins are controlled by spi function.
- idle-high: SCLK pin is pulled-up, but MOSI/MISO are still controlled
by spi function.
- idle-low: SCLK pin is pulled-down, but MOSI/MISO are still controlled
by spi function.

Reported-by: Da Xue <da@libre.computer>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
---
 .../bindings/spi/amlogic,meson-gx-spicc.yaml      | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml b/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
index 50de0da42c13..10707a8216f5 100644
--- a/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
+++ b/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
@@ -43,6 +43,14 @@ properties:
     minItems: 1
     maxItems: 2
 
+  pinctrl-0:
+    minItems: 1
+
+  pinctrl-1:
+    maxItems: 1
+
+  pinctrl-names: true
+
 if:
   properties:
     compatible:
@@ -69,6 +77,13 @@ else:
       items:
         - const: core
 
+    pinctrl-names:
+      minItems: 1
+      items:
+        - const: default
+        - const: idle-high
+        - const: idle-low
+
 required:
   - compatible
   - reg
-- 
2.37.1


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Re: [PATCH 1/2] spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI signal states

[Neil Armstrong]

Hi,

On 09/08/2022 19:20, Amjad Ouled-Ameur wrote:
> SPI pins of the SPICC Controller in Meson-GX needs to be controlled by
> pin biais when idle. Therefore define three pinctrl names:
> - default: SPI pins are controlled by spi function.
> - idle-high: SCLK pin is pulled-up, but MOSI/MISO are still controlled
> by spi function.
> - idle-low: SCLK pin is pulled-down, but MOSI/MISO are still controlled
> by spi function.
> 
> Reported-by: Da Xue <da@libre.computer>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>

Don't forget to CC devicetree@vger.kernel.org otherwise it won't be reviewed.

> ---
>   .../bindings/spi/amlogic,meson-gx-spicc.yaml      | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml b/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
> index 50de0da42c13..10707a8216f5 100644
> --- a/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
> +++ b/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
> @@ -43,6 +43,14 @@ properties:
>       minItems: 1
>       maxItems: 2
>   
> +  pinctrl-0:
> +    minItems: 1
> +
> +  pinctrl-1:
> +    maxItems: 1
> +
> +  pinctrl-names: true
> +
>   if:
>     properties:
>       compatible:
> @@ -69,6 +77,13 @@ else:
>         items:
>           - const: core
>   
> +    pinctrl-names:
> +      minItems: 1
> +      items:
> +        - const: default
> +        - const: idle-high
> +        - const: idle-low
> +
>   required:
>     - compatible
>     - reg

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Re: [PATCH 1/2] spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI signal states

[Amjad Ouled-Ameur]

Hi Neil

On 9/27/22 10:29, Neil Armstrong wrote:
> Hi,
>
> On 09/08/2022 19:20, Amjad Ouled-Ameur wrote:
>> SPI pins of the SPICC Controller in Meson-GX needs to be controlled by
>> pin biais when idle. Therefore define three pinctrl names:
>> - default: SPI pins are controlled by spi function.
>> - idle-high: SCLK pin is pulled-up, but MOSI/MISO are still controlled
>> by spi function.
>> - idle-low: SCLK pin is pulled-down, but MOSI/MISO are still controlled
>> by spi function.
>>
>> Reported-by: Da Xue <da@libre.computer>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
>
> Don't forget to CC devicetree@vger.kernel.org otherwise it won't be 
> reviewed.

Sure, will do in V2.

Regards,

Amjad

>
>
>> ---
>>   .../bindings/spi/amlogic,meson-gx-spicc.yaml      | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git 
>> a/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml 
>> b/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
>> index 50de0da42c13..10707a8216f5 100644
>> --- a/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
>> +++ b/Documentation/devicetree/bindings/spi/amlogic,meson-gx-spicc.yaml
>> @@ -43,6 +43,14 @@ properties:
>>       minItems: 1
>>       maxItems: 2
>>   +  pinctrl-0:
>> +    minItems: 1
>> +
>> +  pinctrl-1:
>> +    maxItems: 1
>> +
>> +  pinctrl-names: true
>> +
>>   if:
>>     properties:
>>       compatible:
>> @@ -69,6 +77,13 @@ else:
>>         items:
>>           - const: core
>>   +    pinctrl-names:
>> +      minItems: 1
>> +      items:
>> +        - const: default
>> +        - const: idle-high
>> +        - const: idle-low
>> +
>>   required:
>>     - compatible
>>     - reg

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[PATCH 2/2] spi: meson-spicc: Use pinctrl to drive CLK line when idle

[Amjad Ouled-Ameur]

Between SPI transactions, all SPI pins are in HiZ state. When using the SS
signal from the SPICC controller it's not an issue because when the
transaction resumes all pins come back to the right state at the same time
as SS.

The problem is when we use CS as a GPIO. In fact, between the GPIO CS
state change and SPI pins state change from idle, you can have a missing or
spurious clock transition.

Set a bias on the clock depending on the clock polarity requested before CS
goes active, by passing a special "idle-low" and "idle-high" pinctrl state
and setting the right state at a start of a message

Reported-by: Da Xue <da@libre.computer>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
---
 arch/arm64/boot/dts/amlogic/meson-gxl.dtsi | 14 ++++++++
 drivers/spi/spi-meson-spicc.c              | 39 +++++++++++++++++++++-
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi b/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
index c3ac531c4f84..04e9d0f1bde0 100644
--- a/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
@@ -429,6 +429,20 @@ mux {
 			};
 		};
 
+		spi_idle_high_pins: spi-idle-high-pins {
+			mux {
+				groups = "spi_sclk";
+				bias-pull-up;
+			};
+		};
+
+		spi_idle_low_pins: spi-idle-low-pins {
+			mux {
+				groups = "spi_sclk";
+				bias-pull-down;
+			};
+		};
+
 		spi_ss0_pins: spi-ss0 {
 			mux {
 				groups = "spi_ss0";
diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
index 0bc7daa7afc8..d42171ee1d61 100644
--- a/drivers/spi/spi-meson-spicc.c
+++ b/drivers/spi/spi-meson-spicc.c
@@ -21,6 +21,7 @@
 #include <linux/types.h>
 #include <linux/interrupt.h>
 #include <linux/reset.h>
+#include <linux/pinctrl/consumer.h>
 
 /*
  * The Meson SPICC controller could support DMA based transfers, but is not
@@ -166,14 +167,31 @@ struct meson_spicc_device {
 	unsigned long			tx_remain;
 	unsigned long			rx_remain;
 	unsigned long			xfer_remain;
+	struct pinctrl			*pinctrl;
+	struct pinctrl_state		*pins_idle_high;
+	struct pinctrl_state		*pins_idle_low;
 };
 
 static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
 {
 	u32 conf;
 
-	if (!spicc->data->has_oen)
+	if (!spicc->data->has_oen) {
+		/* Try to get pinctrl states for idle high/low */
+		spicc->pins_idle_high = pinctrl_lookup_state(spicc->pinctrl,
+							     "idle-high");
+		if (IS_ERR(spicc->pins_idle_high)) {
+			dev_warn(&spicc->pdev->dev, "can't get idle-high pinctrl\n");
+			spicc->pins_idle_high = NULL;
+		}
+		spicc->pins_idle_low = pinctrl_lookup_state(spicc->pinctrl,
+							     "idle-low");
+		if (IS_ERR(spicc->pins_idle_low)) {
+			dev_warn(&spicc->pdev->dev, "can't get idle-low pinctrl\n");
+			spicc->pins_idle_low = NULL;
+		}
 		return;
+	}
 
 	conf = readl_relaxed(spicc->base + SPICC_ENH_CTL0) |
 		SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN;
@@ -438,6 +456,16 @@ static int meson_spicc_prepare_message(struct spi_master *master,
 	else
 		conf &= ~SPICC_POL;
 
+	if (!spicc->data->has_oen) {
+		if (spi->mode & SPI_CPOL) {
+			if (spicc->pins_idle_high)
+				pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_high);
+		} else {
+			if (spicc->pins_idle_low)
+				pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_low);
+		}
+	}
+
 	if (spi->mode & SPI_CPHA)
 		conf |= SPICC_PHA;
 	else
@@ -482,6 +510,9 @@ static int meson_spicc_unprepare_transfer(struct spi_master *master)
 
 	device_reset_optional(&spicc->pdev->dev);
 
+	if (!spicc->data->has_oen)
+		pinctrl_select_default_state(&spicc->pdev->dev);
+
 	return 0;
 }
 
@@ -733,6 +764,12 @@ static int meson_spicc_probe(struct platform_device *pdev)
 		goto out_core_clk;
 	}
 
+	spicc->pinctrl = devm_pinctrl_get(&pdev->dev);
+	if (IS_ERR(spicc->pinctrl)) {
+		ret = PTR_ERR(spicc->pinctrl);
+		goto out_clk;
+	}
+
 	device_reset_optional(&pdev->dev);
 
 	master->num_chipselect = 4;
-- 
2.37.1


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Re: [PATCH 2/2] spi: meson-spicc: Use pinctrl to drive CLK line when idle

[Jerome Brunet]

On Tue 09 Aug 2022 at 19:20, Amjad Ouled-Ameur <aouledameur@baylibre.com> wrote:

> Between SPI transactions, all SPI pins are in HiZ state. When using the SS
> signal from the SPICC controller it's not an issue because when the
> transaction resumes all pins come back to the right state at the same time
> as SS.
>
> The problem is when we use CS as a GPIO. In fact, between the GPIO CS
> state change and SPI pins state change from idle, you can have a missing or
> spurious clock transition.
>
> Set a bias on the clock depending on the clock polarity requested before CS
> goes active, by passing a special "idle-low" and "idle-high" pinctrl state
> and setting the right state at a start of a message
>
> Reported-by: Da Xue <da@libre.computer>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
> ---
>  arch/arm64/boot/dts/amlogic/meson-gxl.dtsi | 14 ++++++++
>  drivers/spi/spi-meson-spicc.c              | 39 +++++++++++++++++++++-

These 2 changes should not be in the same patch.

>  2 files changed, 52 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi b/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
> index c3ac531c4f84..04e9d0f1bde0 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
> +++ b/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi

Does the problem applies only the gxl ? not gxbb, g12, axg ?

> @@ -429,6 +429,20 @@ mux {
>  			};
>  		};
>  
> +		spi_idle_high_pins: spi-idle-high-pins {
> +			mux {
> +				groups = "spi_sclk";
> +				bias-pull-up;
> +			};
> +		};
> +
> +		spi_idle_low_pins: spi-idle-low-pins {
> +			mux {
> +				groups = "spi_sclk";
> +				bias-pull-down;

Would it be safer to properly drive the pin in push-pull mode ?
Like using gpio pinumux mode and output-high/output-low pinconf ?

> +			};
> +		};
> +
>  		spi_ss0_pins: spi-ss0 {
>  			mux {
>  				groups = "spi_ss0";
> diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
> index 0bc7daa7afc8..d42171ee1d61 100644
> --- a/drivers/spi/spi-meson-spicc.c
> +++ b/drivers/spi/spi-meson-spicc.c
> @@ -21,6 +21,7 @@
>  #include <linux/types.h>
>  #include <linux/interrupt.h>
>  #include <linux/reset.h>
> +#include <linux/pinctrl/consumer.h>
>  
>  /*
>   * The Meson SPICC controller could support DMA based transfers, but is not
> @@ -166,14 +167,31 @@ struct meson_spicc_device {
>  	unsigned long			tx_remain;
>  	unsigned long			rx_remain;
>  	unsigned long			xfer_remain;
> +	struct pinctrl			*pinctrl;
> +	struct pinctrl_state		*pins_idle_high;
> +	struct pinctrl_state		*pins_idle_low;
>  };
>  
>  static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
>  {
>  	u32 conf;
>  
> -	if (!spicc->data->has_oen)
> +	if (!spicc->data->has_oen) {
> +		/* Try to get pinctrl states for idle high/low */
> +		spicc->pins_idle_high = pinctrl_lookup_state(spicc->pinctrl,
> +							     "idle-high");
> +		if (IS_ERR(spicc->pins_idle_high)) {
> +			dev_warn(&spicc->pdev->dev, "can't get idle-high pinctrl\n");
> +			spicc->pins_idle_high = NULL;
> +		}
> +		spicc->pins_idle_low = pinctrl_lookup_state(spicc->pinctrl,
> +							     "idle-low");
> +		if (IS_ERR(spicc->pins_idle_low)) {
> +			dev_warn(&spicc->pdev->dev, "can't get idle-low pinctrl\n");
> +			spicc->pins_idle_low = NULL;
> +		}
>  		return;
> +	}
>  
>  	conf = readl_relaxed(spicc->base + SPICC_ENH_CTL0) |
>  		SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN;
> @@ -438,6 +456,16 @@ static int meson_spicc_prepare_message(struct spi_master *master,
>  	else
>  		conf &= ~SPICC_POL;
>  
> +	if (!spicc->data->has_oen) {
> +		if (spi->mode & SPI_CPOL) {
> +			if (spicc->pins_idle_high)
> +				pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_high);
> +		} else {
> +			if (spicc->pins_idle_low)
> +				pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_low);
> +		}
> +	}
> +
>  	if (spi->mode & SPI_CPHA)
>  		conf |= SPICC_PHA;
>  	else
> @@ -482,6 +510,9 @@ static int meson_spicc_unprepare_transfer(struct spi_master *master)
>  
>  	device_reset_optional(&spicc->pdev->dev);
>  
> +	if (!spicc->data->has_oen)
> +		pinctrl_select_default_state(&spicc->pdev->dev);
> +
>  	return 0;
>  }
>  
> @@ -733,6 +764,12 @@ static int meson_spicc_probe(struct platform_device *pdev)
>  		goto out_core_clk;
>  	}
>  
> +	spicc->pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (IS_ERR(spicc->pinctrl)) {
> +		ret = PTR_ERR(spicc->pinctrl);
> +		goto out_clk;
> +	}
> +
>  	device_reset_optional(&pdev->dev);
>  
>  	master->num_chipselect = 4;


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Re: [PATCH 2/2] spi: meson-spicc: Use pinctrl to drive CLK line when idle

[Neil Armstrong]

On 10/08/2022 10:52, Jerome Brunet wrote:
> 
> On Tue 09 Aug 2022 at 19:20, Amjad Ouled-Ameur <aouledameur@baylibre.com> wrote:
> 
>> Between SPI transactions, all SPI pins are in HiZ state. When using the SS
>> signal from the SPICC controller it's not an issue because when the
>> transaction resumes all pins come back to the right state at the same time
>> as SS.
>>
>> The problem is when we use CS as a GPIO. In fact, between the GPIO CS
>> state change and SPI pins state change from idle, you can have a missing or
>> spurious clock transition.
>>
>> Set a bias on the clock depending on the clock polarity requested before CS
>> goes active, by passing a special "idle-low" and "idle-high" pinctrl state
>> and setting the right state at a start of a message
>>
>> Reported-by: Da Xue <da@libre.computer>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com>
>> ---
>>   arch/arm64/boot/dts/amlogic/meson-gxl.dtsi | 14 ++++++++
>>   drivers/spi/spi-meson-spicc.c              | 39 +++++++++++++++++++++-
> 
> These 2 changes should not be in the same patch.
> 
>>   2 files changed, 52 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi b/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
>> index c3ac531c4f84..04e9d0f1bde0 100644
>> --- a/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
>> +++ b/arch/arm64/boot/dts/amlogic/meson-gxl.dtsi
> 
> Does the problem applies only the gxl ? not gxbb, g12, axg ?

Only on GXL, starting from AXG the pins mode output state can be kept between bursts.

> 
>> @@ -429,6 +429,20 @@ mux {
>>   			};
>>   		};
>>   
>> +		spi_idle_high_pins: spi-idle-high-pins {
>> +			mux {
>> +				groups = "spi_sclk";
>> +				bias-pull-up;
>> +			};
>> +		};
>> +
>> +		spi_idle_low_pins: spi-idle-low-pins {
>> +			mux {
>> +				groups = "spi_sclk";
>> +				bias-pull-down;
> 
> Would it be safer to properly drive the pin in push-pull mode ?
> Like using gpio pinumux mode and output-high/output-low pinconf ?

The pins mux must be kept in the SPI function, thus only a bias can be applied.

> 
>> +			};
>> +		};
>> +
>>   		spi_ss0_pins: spi-ss0 {
>>   			mux {
>>   				groups = "spi_ss0";
>> diff --git a/drivers/spi/spi-meson-spicc.c b/drivers/spi/spi-meson-spicc.c
>> index 0bc7daa7afc8..d42171ee1d61 100644
>> --- a/drivers/spi/spi-meson-spicc.c
>> +++ b/drivers/spi/spi-meson-spicc.c
>> @@ -21,6 +21,7 @@
>>   #include <linux/types.h>
>>   #include <linux/interrupt.h>
>>   #include <linux/reset.h>
>> +#include <linux/pinctrl/consumer.h>
>>   
>>   /*
>>    * The Meson SPICC controller could support DMA based transfers, but is not
>> @@ -166,14 +167,31 @@ struct meson_spicc_device {
>>   	unsigned long			tx_remain;
>>   	unsigned long			rx_remain;
>>   	unsigned long			xfer_remain;
>> +	struct pinctrl			*pinctrl;
>> +	struct pinctrl_state		*pins_idle_high;
>> +	struct pinctrl_state		*pins_idle_low;
>>   };
>>   
>>   static void meson_spicc_oen_enable(struct meson_spicc_device *spicc)
>>   {
>>   	u32 conf;
>>   
>> -	if (!spicc->data->has_oen)
>> +	if (!spicc->data->has_oen) {
>> +		/* Try to get pinctrl states for idle high/low */
>> +		spicc->pins_idle_high = pinctrl_lookup_state(spicc->pinctrl,
>> +							     "idle-high");
>> +		if (IS_ERR(spicc->pins_idle_high)) {
>> +			dev_warn(&spicc->pdev->dev, "can't get idle-high pinctrl\n");
>> +			spicc->pins_idle_high = NULL;
>> +		}
>> +		spicc->pins_idle_low = pinctrl_lookup_state(spicc->pinctrl,
>> +							     "idle-low");
>> +		if (IS_ERR(spicc->pins_idle_low)) {
>> +			dev_warn(&spicc->pdev->dev, "can't get idle-low pinctrl\n");
>> +			spicc->pins_idle_low = NULL;
>> +		}
>>   		return;
>> +	}
>>   
>>   	conf = readl_relaxed(spicc->base + SPICC_ENH_CTL0) |
>>   		SPICC_ENH_MOSI_OEN | SPICC_ENH_CLK_OEN | SPICC_ENH_CS_OEN;
>> @@ -438,6 +456,16 @@ static int meson_spicc_prepare_message(struct spi_master *master,
>>   	else
>>   		conf &= ~SPICC_POL;
>>   
>> +	if (!spicc->data->has_oen) {
>> +		if (spi->mode & SPI_CPOL) {
>> +			if (spicc->pins_idle_high)
>> +				pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_high);
>> +		} else {
>> +			if (spicc->pins_idle_low)
>> +				pinctrl_select_state(spicc->pinctrl, spicc->pins_idle_low);
>> +		}
>> +	}
>> +
>>   	if (spi->mode & SPI_CPHA)
>>   		conf |= SPICC_PHA;
>>   	else
>> @@ -482,6 +510,9 @@ static int meson_spicc_unprepare_transfer(struct spi_master *master)
>>   
>>   	device_reset_optional(&spicc->pdev->dev);
>>   
>> +	if (!spicc->data->has_oen)
>> +		pinctrl_select_default_state(&spicc->pdev->dev);
>> +
>>   	return 0;
>>   }
>>   
>> @@ -733,6 +764,12 @@ static int meson_spicc_probe(struct platform_device *pdev)
>>   		goto out_core_clk;
>>   	}
>>   
>> +	spicc->pinctrl = devm_pinctrl_get(&pdev->dev);
>> +	if (IS_ERR(spicc->pinctrl)) {
>> +		ret = PTR_ERR(spicc->pinctrl);
>> +		goto out_clk;
>> +	}
>> +
>>   	device_reset_optional(&pdev->dev);
>>   
>>   	master->num_chipselect = 4;
> 


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Re: [PATCH 0/2] spi: amlogic: meson-spicc: Use pinctrl to drive CLK line when idle

[Neil Armstrong]

Hi Amjad,

On 09/08/2022 19:20, Amjad Ouled-Ameur wrote:
> Between SPI transactions, all SPI pins are in HiZ state. When using the SS
> signal from the SPICC controller it's not an issue because when the
> transaction resumes all pins come back to the right state at the same time
> as SS.
> 
> The problem is when we use CS as a GPIO. In fact, between the GPIO CS
> state change and SPI pins state change from idle, you can have a missing or
> spurious clock transition.
> 
> Set a bias on the clock depending on the clock polarity requested before CS
> goes active, by passing a special "idle-low" and "idle-high" pinctrl state
> and setting the right state at a start of a message.
> 
> Amjad Ouled-Ameur (2):
>    spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI
>      signal states
>    spi: meson-spicc: Use pinctrl to drive CLK line when idle
> 
>   .../bindings/spi/amlogic,meson-gx-spicc.yaml  | 15 +++++++
>   arch/arm64/boot/dts/amlogic/meson-gxl.dtsi    | 14 +++++++
>   drivers/spi/spi-meson-spicc.c                 | 39 ++++++++++++++++++-
>   3 files changed, 67 insertions(+), 1 deletion(-)
> 

Will you send a v2 with comments adresses ?

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Re: [PATCH 0/2] spi: amlogic: meson-spicc: Use pinctrl to drive CLK line when idle

[Amjad Ouled-Ameur]

Hi Neil,

On 9/27/22 10:30, Neil Armstrong wrote:
> Hi Amjad,
>
> On 09/08/2022 19:20, Amjad Ouled-Ameur wrote:
>> Between SPI transactions, all SPI pins are in HiZ state. When using 
>> the SS
>> signal from the SPICC controller it's not an issue because when the
>> transaction resumes all pins come back to the right state at the same 
>> time
>> as SS.
>>
>> The problem is when we use CS as a GPIO. In fact, between the GPIO CS
>> state change and SPI pins state change from idle, you can have a 
>> missing or
>> spurious clock transition.
>>
>> Set a bias on the clock depending on the clock polarity requested 
>> before CS
>> goes active, by passing a special "idle-low" and "idle-high" pinctrl 
>> state
>> and setting the right state at a start of a message.
>>
>> Amjad Ouled-Ameur (2):
>>    spi: dt-bindings: amlogic, meson-gx-spicc: Add pinctrl names for SPI
>>      signal states
>>    spi: meson-spicc: Use pinctrl to drive CLK line when idle
>>
>>   .../bindings/spi/amlogic,meson-gx-spicc.yaml  | 15 +++++++
>>   arch/arm64/boot/dts/amlogic/meson-gxl.dtsi    | 14 +++++++
>>   drivers/spi/spi-meson-spicc.c                 | 39 ++++++++++++++++++-
>>   3 files changed, 67 insertions(+), 1 deletion(-)
>>
>
> Will you send a v2 with comments adresses ?

Planning to send it soon, thank you for the review.

Regards,

Amjad


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