[PATCH] NFC: trf7970a: Correct register settings for 27MHz clock

[PATCH] NFC: trf7970a: Correct register settings for 27MHz clock

[Geoff Lansberry]

In prior commits the selected clock frequency does not propagate
correctly to what is written the the TRF7970A_MODULATOR_SYS_CLK_CTRL
register.
Also fixes a bug that causes the device tree property check to always
pass.

Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
---
 drivers/nfc/trf7970a.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
index 2d1c8ca..c278b0e 100644
--- a/drivers/nfc/trf7970a.c
+++ b/drivers/nfc/trf7970a.c
@@ -2071,7 +2071,7 @@ static int trf7970a_probe(struct spi_device *spi)
 	}
 
 	of_property_read_u32(np, "clock-frequency", &clk_freq);
-	if ((clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) ||
+	if ((clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) &&
 		(clk_freq != TRF7970A_13MHZ_CLOCK_FREQUENCY)) {
 		dev_err(trf->dev,
 			"clock-frequency (%u Hz) unsupported\n",
@@ -2079,6 +2079,13 @@ static int trf7970a_probe(struct spi_device *spi)
 		return -EINVAL;
 	}
 
+	if (clk_freq = TRF7970A_27MHZ_CLOCK_FREQUENCY) {
+		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_27MHZ;
+		dev_dbg(trf->dev, "trf7970a configured for 27MHz crystal\n");
+	} else {
+		trf->modulator_sys_clk_ctrl = 0;
+	}
+
 	if (of_property_read_bool(np, "en2-rf-quirk"))
 		trf->quirks |= TRF7970A_QUIRK_EN2_MUST_STAY_LOW;
 
-- 
2.7.4

Re: [PATCH] NFC: trf7970a: Correct register settings for 27MHz clock

[walter harms]

Am 26.04.2017 15:48, schrieb Geoff Lansberry:
> In prior commits the selected clock frequency does not propagate
> correctly to what is written the the TRF7970A_MODULATOR_SYS_CLK_CTRL
> register.
> Also fixes a bug that causes the device tree property check to always
> pass.
> 
> Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
> ---
>  drivers/nfc/trf7970a.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
> index 2d1c8ca..c278b0e 100644
> --- a/drivers/nfc/trf7970a.c
> +++ b/drivers/nfc/trf7970a.c
> @@ -2071,7 +2071,7 @@ static int trf7970a_probe(struct spi_device *spi)
>  	}
>  
>  	of_property_read_u32(np, "clock-frequency", &clk_freq);
> -	if ((clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) ||
> +	if ((clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) &&
>  		(clk_freq != TRF7970A_13MHZ_CLOCK_FREQUENCY)) {
>  		dev_err(trf->dev,
>  			"clock-frequency (%u Hz) unsupported\n",
> @@ -2079,6 +2079,13 @@ static int trf7970a_probe(struct spi_device *spi)
>  		return -EINVAL;
>  	}
>  
> +	if (clk_freq = TRF7970A_27MHZ_CLOCK_FREQUENCY) {
> +		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_27MHZ;
> +		dev_dbg(trf->dev, "trf7970a configured for 27MHz crystal\n");
> +	} else {
> +		trf->modulator_sys_clk_ctrl = 0;
> +	}
> +


I am a fan of defensive programming and would move do:
trf->modulator_sys_clk_ctrl = 0;
if (clk_freq = TRF7970A_27MHZ_CLOCK_FREQUENCY) {
		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_27MHZ;
		dev_dbg(trf->dev, "trf7970a configured for 27MHz crystal\n");
	}

perhaps using a switch/case here is appropriate IMHO a border case for 2 case
but would make the init code more clear.

just my 2 cents,

re,
 wh

>  	if (of_property_read_bool(np, "en2-rf-quirk"))
>  		trf->quirks |= TRF7970A_QUIRK_EN2_MUST_STAY_LOW;
>  

Re: [PATCH] NFC: trf7970a: Correct register settings for 27MHz clock

[Mark Greer]

On Wed, Apr 26, 2017 at 09:48:33AM -0400, Geoff Lansberry wrote:
> In prior commits the selected clock frequency does not propagate
> correctly to what is written the the TRF7970A_MODULATOR_SYS_CLK_CTRL
> register.
> Also fixes a bug that causes the device tree property check to always
> pass.
> 
> Signed-off-by: Geoff Lansberry <geoff@kuvee.com>
> ---
>  drivers/nfc/trf7970a.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
> index 2d1c8ca..c278b0e 100644
> --- a/drivers/nfc/trf7970a.c
> +++ b/drivers/nfc/trf7970a.c
> @@ -2071,7 +2071,7 @@ static int trf7970a_probe(struct spi_device *spi)
>  	}
>  
>  	of_property_read_u32(np, "clock-frequency", &clk_freq);
> -	if ((clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) ||
> +	if ((clk_freq != TRF7970A_27MHZ_CLOCK_FREQUENCY) &&

There is already a patch submitted to fix this issue so no need to fix
it again.  For the record, it should have been in a separate patch
since it fixes a different issue than what is fixed below.

>  		(clk_freq != TRF7970A_13MHZ_CLOCK_FREQUENCY)) {
>  		dev_err(trf->dev,
>  			"clock-frequency (%u Hz) unsupported\n",
> @@ -2079,6 +2079,13 @@ static int trf7970a_probe(struct spi_device *spi)
>  		return -EINVAL;
>  	}
>  
> +	if (clk_freq = TRF7970A_27MHZ_CLOCK_FREQUENCY) {
> +		trf->modulator_sys_clk_ctrl = TRF7970A_MODULATOR_27MHZ;
> +		dev_dbg(trf->dev, "trf7970a configured for 27MHz crystal\n");
> +	} else {
> +		trf->modulator_sys_clk_ctrl = 0;
> +	}
> +
>  	if (of_property_read_bool(np, "en2-rf-quirk"))
>  		trf->quirks |= TRF7970A_QUIRK_EN2_MUST_STAY_LOW;

This part looks okay to me but I like Walter's suggestion too.

Mark
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