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From: Jonathan Cameron <jic23@kernel.org>
To: Eugen Hristev <eugen.hristev@microchip.com>
Cc: <nicolas.ferre@microchip.com>,
	<alexandre.belloni@free-electrons.com>,
	<linux-iio@vger.kernel.org>, <lars@metafoo.de>,
	<linux-arm-kernel@lists.infradead.org>,
	<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<ludovic.desroches@microchip.com>
Subject: Re: [PATCH v2 5/5] iio: adc: at91-sama5d2_adc: use max sample rate
Date: Sun, 15 Oct 2017 11:28:47 +0100	[thread overview]
Message-ID: <20171015112847.5c035e7a@archlinux> (raw)
In-Reply-To: <1507703732-29175-6-git-send-email-eugen.hristev@microchip.com>

On Wed, 11 Oct 2017 09:35:32 +0300
Eugen Hristev <eugen.hristev@microchip.com> wrote:

> Change driver settings to use maximum sample rate clock.
> This is useful to achieve best possible sampling rate
> if we use DMA.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

I would normally expect this to have some bearing on the 
noise levels on the measured signals.  All I can find
is a reference to the track time being 15*a single
clock cycle.  We could change this so that it is appropriate
for the currently samping frequency rather than leaving it
as a fixed value.

Jonathan

> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 7e51ecb..b76f88f 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -934,7 +934,7 @@ static void at91_adc_hw_init(struct at91_adc_state *st)
>  	at91_adc_writel(st, AT91_SAMA5D2_MR,
>  			AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
>  
> -	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
> +	at91_adc_setup_samp_freq(st, st->soc_info.max_sample_rate);
>  }
>  
>  static ssize_t at91_adc_get_fifo_state(struct device *dev,

WARNING: multiple messages have this Message-ID (diff)
From: Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
To: Eugen Hristev <eugen.hristev-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>
Cc: nicolas.ferre-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org,
	alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org,
	linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
	devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	ludovic.desroches-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org
Subject: Re: [PATCH v2 5/5] iio: adc: at91-sama5d2_adc: use max sample rate
Date: Sun, 15 Oct 2017 11:28:47 +0100	[thread overview]
Message-ID: <20171015112847.5c035e7a@archlinux> (raw)
In-Reply-To: <1507703732-29175-6-git-send-email-eugen.hristev-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>

On Wed, 11 Oct 2017 09:35:32 +0300
Eugen Hristev <eugen.hristev-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org> wrote:

> Change driver settings to use maximum sample rate clock.
> This is useful to achieve best possible sampling rate
> if we use DMA.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev-UWL1GkI3JZL3oGB3hsPCZA@public.gmane.org>

I would normally expect this to have some bearing on the 
noise levels on the measured signals.  All I can find
is a reference to the track time being 15*a single
clock cycle.  We could change this so that it is appropriate
for the currently samping frequency rather than leaving it
as a fixed value.

Jonathan

> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 7e51ecb..b76f88f 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -934,7 +934,7 @@ static void at91_adc_hw_init(struct at91_adc_state *st)
>  	at91_adc_writel(st, AT91_SAMA5D2_MR,
>  			AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
>  
> -	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
> +	at91_adc_setup_samp_freq(st, st->soc_info.max_sample_rate);
>  }
>  
>  static ssize_t at91_adc_get_fifo_state(struct device *dev,

WARNING: multiple messages have this Message-ID (diff)
From: jic23@kernel.org (Jonathan Cameron)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 5/5] iio: adc: at91-sama5d2_adc: use max sample rate
Date: Sun, 15 Oct 2017 11:28:47 +0100	[thread overview]
Message-ID: <20171015112847.5c035e7a@archlinux> (raw)
In-Reply-To: <1507703732-29175-6-git-send-email-eugen.hristev@microchip.com>

On Wed, 11 Oct 2017 09:35:32 +0300
Eugen Hristev <eugen.hristev@microchip.com> wrote:

> Change driver settings to use maximum sample rate clock.
> This is useful to achieve best possible sampling rate
> if we use DMA.
> 
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>

I would normally expect this to have some bearing on the 
noise levels on the measured signals.  All I can find
is a reference to the track time being 15*a single
clock cycle.  We could change this so that it is appropriate
for the currently samping frequency rather than leaving it
as a fixed value.

Jonathan

> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 7e51ecb..b76f88f 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -934,7 +934,7 @@ static void at91_adc_hw_init(struct at91_adc_state *st)
>  	at91_adc_writel(st, AT91_SAMA5D2_MR,
>  			AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
>  
> -	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
> +	at91_adc_setup_samp_freq(st, st->soc_info.max_sample_rate);
>  }
>  
>  static ssize_t at91_adc_get_fifo_state(struct device *dev,

  reply	other threads:[~2017-10-15 10:28 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-11  6:35 [PATCH v2 0/5] iio: adc: at91-sama5d2_adc: add DMA support Eugen Hristev
2017-10-11  6:35 ` Eugen Hristev
2017-10-11  6:35 ` Eugen Hristev
2017-10-11  6:35 ` [PATCH v2 1/5] dt-bindings: iio: at91-sama5d2_adc: add optional dma property Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-13 21:51   ` Rob Herring
2017-10-13 21:51     ` Rob Herring
2017-10-19 11:14     ` Alexandre Belloni
2017-10-19 11:14       ` Alexandre Belloni
2017-10-19 21:58       ` Rob Herring
2017-10-19 21:58         ` Rob Herring
2017-10-19 21:58         ` Rob Herring
2017-10-19 21:58         ` Rob Herring
2017-11-07  8:49         ` Eugen Hristev
2017-11-07  8:49           ` Eugen Hristev
2017-11-07  8:49           ` Eugen Hristev
2017-11-07  8:49           ` Eugen Hristev
2017-11-07  9:02           ` Ludovic Desroches
2017-11-07  9:02             ` Ludovic Desroches
2017-11-07  9:02             ` Ludovic Desroches
2017-10-11  6:35 ` [PATCH v2 2/5] ARM: dts: at91: sama5d2: added dma property for ADC device Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35 ` [PATCH v2 3/5] iio: adc: at91-sama5d2_adc: add support for DMA Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-15 10:16   ` Jonathan Cameron
2017-10-15 10:16     ` Jonathan Cameron
2017-10-15 10:16     ` Jonathan Cameron
2017-10-11  6:35 ` [PATCH v2 4/5] iio: adc: at91-sama5d2_adc: ack DRDY irq in direct mode Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35 ` [PATCH v2 5/5] iio: adc: at91-sama5d2_adc: use max sample rate Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-11  6:35   ` Eugen Hristev
2017-10-15 10:28   ` Jonathan Cameron [this message]
2017-10-15 10:28     ` Jonathan Cameron
2017-10-15 10:28     ` Jonathan Cameron
2017-10-18  8:49     ` Eugen Hristev
2017-10-18  8:49       ` Eugen Hristev
2017-10-18  8:49       ` Eugen Hristev

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