Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-11-10 Thread Vignesh R


On Friday 11 November 2016 09:00 AM, John Syne wrote:
> 
>> On Nov 9, 2016, at 9:07 PM, Vignesh R  wrote:
>>
>> Hi,
>>
>> On Thursday 10 November 2016 05:23 AM, John Syne wrote:
>>> OK, then back to my original question. Given that these DT properties are 
>>> supported in the driver
>>>
>>
>> Below properties are supported by only by ti_am3335x_adc driver and not
>> ti_am335x_tsc driver. As author of this patch pointed out in another
>> reply, there is no need to change step-opendelay for tsc. AFAIK, I don't
>> see a use case where these values needs to be tweaked for tsc channels,
>> therefore it does not make sense to be DT properties.
> Yeah, the confusion was mine because the author of this patch series was 
> proposing to hard code these settings while DT properties already existed in 
> the ti_am335x_adc driver. I use the ADC for sensor measurement and do not use 
> the touchscreen features. I already pointed out where these DT parameters 
> should be added by referencing how this was done in one of the BBB DT overlay 
> files [1]. I am just proposing the same is done as a default in the 
> AM33xx.dtsi and AM4372.dtsi files. Here is what I was proposing. 

> Granted, the adc-channels should be restricted to the subset of channels not 
> used by tsc, but you get the idea.

There are 4 wire, 5 wire and 8 wire touchscreens. Therefore there is no
way to know in advance, how many channels are available for adc. IMO,
this is not a SoC specific configuration but board dependent. Hence, all
channel related configurations need to be in board specific dts files
and not in top level dtsi files.

> 
> tscadc: tscadc@44e0d000 {
>   compatible = "ti,am3359-tscadc";
>   reg = <0x44e0d000 0x1000>;
>   interrupt-parent = <&intc>;
>   interrupts = <16>;
>   ti,hwmods = "adc_tsc";
>   status = "disabled";
>   dmas = <&edma 53 0>, <&edma 57 0>;
>   dma-names = "fifo0", "fifo1”;
> 
>   tsc {
>   compatible = "ti,am3359-tsc";
>   };
>   am335x_adc: adc {
>   #io-channel-cells = <1>;
>   ti,adc-channels = <0 1 2 3 4 5 6>;
>   ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 
> 0x16 0x16>;
>   ti,chan-step-opendelay = <0x98 0x98 0x98 0x98 
> 0x98 0x98 0x98>;
>   ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 
> 0x0 0x0>;
>   compatible = "ti,am3359-adc";
>   };
> };
> 
> [1]https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
> 

-- 
Regards
Vignesh


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-11-10 Thread John Syne

> On Nov 9, 2016, at 9:07 PM, Vignesh R  wrote:
> 
> Hi,
> 
> On Thursday 10 November 2016 05:23 AM, John Syne wrote:
>> OK, then back to my original question. Given that these DT properties are 
>> supported in the driver
>> 
> 
> Below properties are supported by only by ti_am3335x_adc driver and not
> ti_am335x_tsc driver. As author of this patch pointed out in another
> reply, there is no need to change step-opendelay for tsc. AFAIK, I don't
> see a use case where these values needs to be tweaked for tsc channels,
> therefore it does not make sense to be DT properties.
Yeah, the confusion was mine because the author of this patch series was 
proposing to hard code these settings while DT properties already existed in 
the ti_am335x_adc driver. I use the ADC for sensor measurement and do not use 
the touchscreen features. I already pointed out where these DT parameters 
should be added by referencing how this was done in one of the BBB DT overlay 
files [1]. I am just proposing the same is done as a default in the AM33xx.dtsi 
and AM4372.dtsi files. Here is what I was proposing. Granted, the adc-channels 
should be restricted to the subset of channels not used by tsc, but you get the 
idea.

tscadc: tscadc@44e0d000 {
compatible = "ti,am3359-tscadc";
reg = <0x44e0d000 0x1000>;
interrupt-parent = <&intc>;
interrupts = <16>;
ti,hwmods = "adc_tsc";
status = "disabled";
dmas = <&edma 53 0>, <&edma 57 0>;
dma-names = "fifo0", "fifo1”;

tsc {
compatible = "ti,am3359-tsc";
};
am335x_adc: adc {
#io-channel-cells = <1>;
ti,adc-channels = <0 1 2 3 4 5 6>;
ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 
0x16 0x16>;
ti,chan-step-opendelay = <0x98 0x98 0x98 0x98 
0x98 0x98 0x98>;
ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 
0x0 0x0>;
compatible = "ti,am3359-adc";
};
};

[1]https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts

Regards,
John
> 
>> shouldn’t the following be added to am33xx.dtsi and am4372.dtsi?
> 
> Its totally upto board dts files to allocate channels for tsc and adc.
> So, how could these be added to dtsi files?
> 
>> ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>> ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
>> ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>> 
>> Regards,
>> John
>>> 
>>> -- 
>>> Regards
>>> Vignesh
>> 
> 
> -- 
> Regards
> Vignesh



Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-11-09 Thread Vignesh R
Hi,

On Thursday 10 November 2016 05:23 AM, John Syne wrote:
> OK, then back to my original question. Given that these DT properties are 
> supported in the driver
> 

Below properties are supported by only by ti_am3335x_adc driver and not
ti_am335x_tsc driver. As author of this patch pointed out in another
reply, there is no need to change step-opendelay for tsc. AFAIK, I don't
see a use case where these values needs to be tweaked for tsc channels,
therefore it does not make sense to be DT properties.

> shouldn’t the following be added to am33xx.dtsi and am4372.dtsi?

Its totally upto board dts files to allocate channels for tsc and adc.
So, how could these be added to dtsi files?

> ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
> ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
> ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
> 
> Regards,
> John
>>
>> -- 
>> Regards
>> Vignesh
> 

-- 
Regards
Vignesh


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-11-09 Thread John Syne

> On Oct 31, 2016, at 4:39 AM, Vignesh R  wrote:
> 
> 
> 
> On Friday 28 October 2016 02:47 AM, John Syne wrote:
> 
>>> 
>>> ---
>>> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
>>> b/include/linux/mfd/ti_am335x_tscadc.h
>>> index b9a53e0..96c4207 100644
>>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>>> @@ -90,7 +90,7 @@
>>> /* Delay register */
>>> #define STEPDELAY_OPEN_MASK (0x3 << 0)
>>> #define STEPDELAY_OPEN(val) ((val) << 0)
>>> -#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
> Wouldn’t this be better to add this to the devicetree?
> 
>   ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>   ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 
> 0x500>;
>   ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
 
 For a touch screen, there is not need to change in these parameter
 settings, so my opinion is to keep it as is. Or am I missing something?
>>> I was thinking that if you are using this driver as an ADC, you may 
>>> want the flexibility to make these changes in the DT. I’m doing this by 
>>> connecting sensors to the ADC inputs. I’m not using this driver for a 
>>> touchscreen. 
>> 
>> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
>> 
>> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
>> 
>> Besides, these DT features are already implemented in the driver so it 
>> is just a matter of adding these entries to the am33xx.dtsi & 
>> am4372.dtsi, which you modified in this patch series.
> 
> This looks like configuration, no?
> 
> DT should be used to describe the hardware.
 You may be right, but how is this different to setting the baud rate on a 
 serial channel or sampling rate on a audio channel? Looking through the 
 DT, there are many configuration settings, so I’m not sure what is the 
 correct way to handle this. Surely it is better to handle this in DT vs 
 hard coding these settings?
>>> 
>>> I think setting the UART baud rate is also an invalid DT entry.
>>> 
>>> It's okay to list all of the options in DT, but to actually select
>>> one, that should be done either in userspace or as a kernel option.
>>> Perhaps as a Kconfig selection.
>> Yeah, this has been inconsistent for a long time. My only point was that 
>> these DT parameters had already been implemented in the ti_am335x_adc KM and 
>> I thought that this was better than hard coding these settings. Implementing 
>> this in Kconfig means rebuilding the KM, which isn’t desirable. 
> 
>> Perhaps this should be done via sysfs attributes so as you say, a userspace 
>> app can configure this driver. 
> 
> This was discussed when DT properties were added.  Patches are welcome
> to add sysfs entries. There is nothing wrong with specifying an initial
> value in the DT.
> 
>> I guess the DT code in ti_am335x_adc.c should be removed. 
>> 
> 
> Removing DT properties is not an option as it will break DT backward
> compatibility.
Hi Vignesh,

OK, then back to my original question. Given that these DT properties are 
supported in the driver, shouldn’t the following be added to am33xx.dtsi and 
am4372.dtsi?

ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;

Regards,
John
> 
> -- 
> Regards
> Vignesh



Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-31 Thread Vignesh R


On Friday 28 October 2016 02:47 AM, John Syne wrote:

>>
>> ---
>> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
>> b/include/linux/mfd/ti_am335x_tscadc.h
>> index b9a53e0..96c4207 100644
>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>> @@ -90,7 +90,7 @@
>> /* Delay register */
>> #define STEPDELAY_OPEN_MASK  (0x3 << 0)
>> #define STEPDELAY_OPEN(val)  ((val) << 0)
>> -#define STEPCONFIG_OPENDLY  STEPDELAY_OPEN(0x098)
 Wouldn’t this be better to add this to the devicetree?

ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 
 0x500>;
ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>>>
>>> For a touch screen, there is not need to change in these parameter
>>> settings, so my opinion is to keep it as is. Or am I missing something?
>> I was thinking that if you are using this driver as an ADC, you may want 
>> the flexibility to make these changes in the DT. I’m doing this by 
>> connecting sensors to the ADC inputs. I’m not using this driver for a 
>> touchscreen. 
>
> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
>
> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
>
> Besides, these DT features are already implemented in the driver so it is 
> just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, 
> which you modified in this patch series.

 This looks like configuration, no?

 DT should be used to describe the hardware.
>>> You may be right, but how is this different to setting the baud rate on a 
>>> serial channel or sampling rate on a audio channel? Looking through the DT, 
>>> there are many configuration settings, so I’m not sure what is the correct 
>>> way to handle this. Surely it is better to handle this in DT vs hard coding 
>>> these settings?
>>
>> I think setting the UART baud rate is also an invalid DT entry.
>>
>> It's okay to list all of the options in DT, but to actually select
>> one, that should be done either in userspace or as a kernel option.
>> Perhaps as a Kconfig selection.
> Yeah, this has been inconsistent for a long time. My only point was that 
> these DT parameters had already been implemented in the ti_am335x_adc KM and 
> I thought that this was better than hard coding these settings. Implementing 
> this in Kconfig means rebuilding the KM, which isn’t desirable. 

>Perhaps this should be done via sysfs attributes so as you say, a userspace 
>app can configure this driver. 

This was discussed when DT properties were added.  Patches are welcome
to add sysfs entries. There is nothing wrong with specifying an initial
value in the DT.

>I guess the DT code in ti_am335x_adc.c should be removed. 
> 

Removing DT properties is not an option as it will break DT backward
compatibility.

-- 
Regards
Vignesh


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-27 Thread John Syne
> 
> On Oct 26, 2016, at 1:48 AM, Lee Jones  wrote:
> 
> On Tue, 25 Oct 2016, John Syne wrote:
>>> On Oct 24, 2016, at 11:38 PM, Lee Jones  wrote:
>>> On Mon, 24 Oct 2016, John Syne wrote:
> On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
>> On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
>> 
>> On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
> On Oct 23, 2016, at 11:02 PM, Mugunthan V N  
> wrote:
> 
> Increase ADC reference clock from 3MHz to 24MHz so that the
> sampling rates goes up from 100K samples per second to 800K
> samples per second on AM335x and AM437x SoC.
> 
> Also increase opendelay for touchscreen configuration to
> equalize the increase in ADC reference clock frequency,
> which results in the same amount touch events reported via
> evtest on AM335x GP EVM.
> 
> Signed-off-by: Mugunthan V N 
> ---
> 
> This patch depends on ADC DMA patch series [1]
> 
> Without DMA support, when ADC ref clock is set at 24MHz, I am
> seeing fifo overflow as CPU is not able to pull the ADC samples.
> This answers that DMA support is must for ADC to consume the
> samples generated at 24MHz with no open, step delay or
> averaging with patch [2].
> 
> Measured the performance with the iio_generic_buffer with the
> patch [3] applied
> 
> [1] - http://www.spinics.net/lists/devicetree/msg145045.html
> [2] - http://pastebin.ubuntu.com/23357935/
> [3] - http://pastebin.ubuntu.com/23357939/
> 
> ---
> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
> b/include/linux/mfd/ti_am335x_tscadc.h
> index b9a53e0..96c4207 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -90,7 +90,7 @@
> /* Delay register */
> #define STEPDELAY_OPEN_MASK   (0x3 << 0)
> #define STEPDELAY_OPEN(val)   ((val) << 0)
> -#define STEPCONFIG_OPENDLY   STEPDELAY_OPEN(0x098)
>>> Wouldn’t this be better to add this to the devicetree?
>>> 
>>> ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>>> ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 
>>> 0x500>;
>>> ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>> 
>> For a touch screen, there is not need to change in these parameter
>> settings, so my opinion is to keep it as is. Or am I missing something?
> I was thinking that if you are using this driver as an ADC, you may want 
> the flexibility to make these changes in the DT. I’m doing this by 
> connecting sensors to the ADC inputs. I’m not using this driver for a 
> touchscreen. 
 
 Here is a DT overlay were this gets using on the BeagleBoneBlack.  
 
 https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
 
 Besides, these DT features are already implemented in the driver so it is 
 just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, 
 which you modified in this patch series.
>>> 
>>> This looks like configuration, no?
>>> 
>>> DT should be used to describe the hardware.
>> You may be right, but how is this different to setting the baud rate on a 
>> serial channel or sampling rate on a audio channel? Looking through the DT, 
>> there are many configuration settings, so I’m not sure what is the correct 
>> way to handle this. Surely it is better to handle this in DT vs hard coding 
>> these settings?
> 
> I think setting the UART baud rate is also an invalid DT entry.
> 
> It's okay to list all of the options in DT, but to actually select
> one, that should be done either in userspace or as a kernel option.
> Perhaps as a Kconfig selection.
Yeah, this has been inconsistent for a long time. My only point was that these 
DT parameters had already been implemented in the ti_am335x_adc KM and I 
thought that this was better than hard coding these settings. Implementing this 
in Kconfig means rebuilding the KM, which isn’t desirable. Perhaps this should 
be done via sysfs attributes so as you say, a userspace app can configure this 
driver. I guess the DT code in ti_am335x_adc.c should be removed. 

Regards,
John
> 
> -- 
> Lee Jones
> Linaro STMicroelectronics Landing Team Lead
> Linaro.org │ Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-27 Thread Mugunthan V N
On Monday 24 October 2016 11:32 AM, Mugunthan V N wrote:
> Increase ADC reference clock from 3MHz to 24MHz so that the
> sampling rates goes up from 100K samples per second to 800K
> samples per second on AM335x and AM437x SoC.
> 
> Also increase opendelay for touchscreen configuration to
> equalize the increase in ADC reference clock frequency,
> which results in the same amount touch events reported via
> evtest on AM335x GP EVM.
> 
> Signed-off-by: Mugunthan V N 

Found issues with touchscreen usage with GUI on my AM335x GP EVM. Fixed
with change the "ti,charge-delay" DT property based on change in ADC
clocks. Will be sending v2 patch soon.

Regards
Mugunthan V N


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-26 Thread Lee Jones
On Tue, 25 Oct 2016, John Syne wrote:
> > On Oct 24, 2016, at 11:38 PM, Lee Jones  wrote:
> > On Mon, 24 Oct 2016, John Syne wrote:
> >>> On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
>  On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
>  
>  On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
> >>> On Oct 23, 2016, at 11:02 PM, Mugunthan V N  
> >>> wrote:
> >>> 
> >>> Increase ADC reference clock from 3MHz to 24MHz so that the
> >>> sampling rates goes up from 100K samples per second to 800K
> >>> samples per second on AM335x and AM437x SoC.
> >>> 
> >>> Also increase opendelay for touchscreen configuration to
> >>> equalize the increase in ADC reference clock frequency,
> >>> which results in the same amount touch events reported via
> >>> evtest on AM335x GP EVM.
> >>> 
> >>> Signed-off-by: Mugunthan V N 
> >>> ---
> >>> 
> >>> This patch depends on ADC DMA patch series [1]
> >>> 
> >>> Without DMA support, when ADC ref clock is set at 24MHz, I am
> >>> seeing fifo overflow as CPU is not able to pull the ADC samples.
> >>> This answers that DMA support is must for ADC to consume the
> >>> samples generated at 24MHz with no open, step delay or
> >>> averaging with patch [2].
> >>> 
> >>> Measured the performance with the iio_generic_buffer with the
> >>> patch [3] applied
> >>> 
> >>> [1] - http://www.spinics.net/lists/devicetree/msg145045.html
> >>> [2] - http://pastebin.ubuntu.com/23357935/
> >>> [3] - http://pastebin.ubuntu.com/23357939/
> >>> 
> >>> ---
> >>> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
> >>> 1 file changed, 2 insertions(+), 2 deletions(-)
> >>> 
> >>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
> >>> b/include/linux/mfd/ti_am335x_tscadc.h
> >>> index b9a53e0..96c4207 100644
> >>> --- a/include/linux/mfd/ti_am335x_tscadc.h
> >>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> >>> @@ -90,7 +90,7 @@
> >>> /* Delay register */
> >>> #define STEPDELAY_OPEN_MASK   (0x3 << 0)
> >>> #define STEPDELAY_OPEN(val)   ((val) << 0)
> >>> -#define STEPCONFIG_OPENDLY   STEPDELAY_OPEN(0x098)
> > Wouldn’t this be better to add this to the devicetree?
> > 
> > ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
> > ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 
> > 0x500>;
> > ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>  
>  For a touch screen, there is not need to change in these parameter
>  settings, so my opinion is to keep it as is. Or am I missing something?
> >>> I was thinking that if you are using this driver as an ADC, you may want 
> >>> the flexibility to make these changes in the DT. I’m doing this by 
> >>> connecting sensors to the ADC inputs. I’m not using this driver for a 
> >>> touchscreen. 
> >> 
> >> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
> >> 
> >> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
> >> 
> >> Besides, these DT features are already implemented in the driver so it is 
> >> just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, 
> >> which you modified in this patch series.
> > 
> > This looks like configuration, no?
> > 
> > DT should be used to describe the hardware.
> You may be right, but how is this different to setting the baud rate on a 
> serial channel or sampling rate on a audio channel? Looking through the DT, 
> there are many configuration settings, so I’m not sure what is the correct 
> way to handle this. Surely it is better to handle this in DT vs hard coding 
> these settings?

I think setting the UART baud rate is also an invalid DT entry.

It's okay to list all of the options in DT, but to actually select
one, that should be done either in userspace or as a kernel option.
Perhaps as a Kconfig selection.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-25 Thread John Syne

> On Oct 24, 2016, at 11:38 PM, Lee Jones  wrote:
> 
> On Mon, 24 Oct 2016, John Syne wrote:
>>> On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
 On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
 
 On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
>>> On Oct 23, 2016, at 11:02 PM, Mugunthan V N  wrote:
>>> 
>>> Increase ADC reference clock from 3MHz to 24MHz so that the
>>> sampling rates goes up from 100K samples per second to 800K
>>> samples per second on AM335x and AM437x SoC.
>>> 
>>> Also increase opendelay for touchscreen configuration to
>>> equalize the increase in ADC reference clock frequency,
>>> which results in the same amount touch events reported via
>>> evtest on AM335x GP EVM.
>>> 
>>> Signed-off-by: Mugunthan V N 
>>> ---
>>> 
>>> This patch depends on ADC DMA patch series [1]
>>> 
>>> Without DMA support, when ADC ref clock is set at 24MHz, I am
>>> seeing fifo overflow as CPU is not able to pull the ADC samples.
>>> This answers that DMA support is must for ADC to consume the
>>> samples generated at 24MHz with no open, step delay or
>>> averaging with patch [2].
>>> 
>>> Measured the performance with the iio_generic_buffer with the
>>> patch [3] applied
>>> 
>>> [1] - http://www.spinics.net/lists/devicetree/msg145045.html
>>> [2] - http://pastebin.ubuntu.com/23357935/
>>> [3] - http://pastebin.ubuntu.com/23357939/
>>> 
>>> ---
>>> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
>>> b/include/linux/mfd/ti_am335x_tscadc.h
>>> index b9a53e0..96c4207 100644
>>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>>> @@ -90,7 +90,7 @@
>>> /* Delay register */
>>> #define STEPDELAY_OPEN_MASK (0x3 << 0)
>>> #define STEPDELAY_OPEN(val) ((val) << 0)
>>> -#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
> Wouldn’t this be better to add this to the devicetree?
> 
>   ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>   ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
>   ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
 
 For a touch screen, there is not need to change in these parameter
 settings, so my opinion is to keep it as is. Or am I missing something?
>>> I was thinking that if you are using this driver as an ADC, you may want 
>>> the flexibility to make these changes in the DT. I’m doing this by 
>>> connecting sensors to the ADC inputs. I’m not using this driver for a 
>>> touchscreen. 
>> 
>> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
>> 
>> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
>> 
>> Besides, these DT features are already implemented in the driver so it is 
>> just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, 
>> which you modified in this patch series.
> 
> This looks like configuration, no?
> 
> DT should be used to describe the hardware.
You may be right, but how is this different to setting the baud rate on a 
serial channel or sampling rate on a audio channel? Looking through the DT, 
there are many configuration settings, so I’m not sure what is the correct way 
to handle this. Surely it is better to handle this in DT vs hard coding these 
settings?

Regards,
John
> 
> -- 
> Lee Jones
> Linaro STMicroelectronics Landing Team Lead
> Linaro.org │ Open source software for ARM SoCs
> Follow Linaro: Facebook | Twitter | Blog



Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-25 Thread John Syne

> On Oct 24, 2016, at 11:37 PM, Vignesh R  wrote:
> 
> 
> 
> On Tuesday 25 October 2016 11:46 AM, John Syne wrote:
>> 
>>> On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
>>> 
 
 On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
 
> [...]
>>> 
>>> ---
>>> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
>>> b/include/linux/mfd/ti_am335x_tscadc.h
>>> index b9a53e0..96c4207 100644
>>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>>> @@ -90,7 +90,7 @@
>>> /* Delay register */
>>> #define STEPDELAY_OPEN_MASK (0x3 << 0)
>>> #define STEPDELAY_OPEN(val) ((val) << 0)
>>> -#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
> Wouldn’t this be better to add this to the devicetree?
> 
>   ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>   ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
>   ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
 
 For a touch screen, there is not need to change in these parameter
 settings, so my opinion is to keep it as is. Or am I missing something?
>>> I was thinking that if you are using this driver as an ADC, you may want 
>>> the flexibility to make these changes in the DT. I’m doing this by 
>>> connecting sensors to the ADC inputs. I’m not using this driver for a 
>>> touchscreen.
>> 
> 
> ti_am335x_adc driver already supports above DT parameters and its upto
> the user to adjust these parameters as required.
> 
>> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
>> 
>> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
>> 
>> Besides, these DT features are already implemented in the driver so it is 
>> just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, 
>> which you modified in this patch series.
>> 
> 
> Touchscreen driver (ti_am335x_tsc.c) does not support above DT parameters.
This patch series also modifies ti_am335x_adc.c

https://github.com/analogdevicesinc/linux/blob/master/drivers/iio/adc/ti_am335x_adc.c#L447

Regards,
John
> 
> -- 
> Regards
> Vignesh



Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-24 Thread Vignesh R


On Tuesday 25 October 2016 11:46 AM, John Syne wrote:
> 
>> On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
>>
>>>
>>> On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
>>>
[...]
>>
>> ---
>> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
>> b/include/linux/mfd/ti_am335x_tscadc.h
>> index b9a53e0..96c4207 100644
>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>> @@ -90,7 +90,7 @@
>> /* Delay register */
>> #define STEPDELAY_OPEN_MASK  (0x3 << 0)
>> #define STEPDELAY_OPEN(val)  ((val) << 0)
>> -#define STEPCONFIG_OPENDLY  STEPDELAY_OPEN(0x098)
 Wouldn’t this be better to add this to the devicetree?

ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>>>
>>> For a touch screen, there is not need to change in these parameter
>>> settings, so my opinion is to keep it as is. Or am I missing something?
>> I was thinking that if you are using this driver as an ADC, you may want the 
>> flexibility to make these changes in the DT. I’m doing this by connecting 
>> sensors to the ADC inputs. I’m not using this driver for a touchscreen.
> 

ti_am335x_adc driver already supports above DT parameters and its upto
the user to adjust these parameters as required.

> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
> 
> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
> 
> Besides, these DT features are already implemented in the driver so it is 
> just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, which 
> you modified in this patch series.
> 

Touchscreen driver (ti_am335x_tsc.c) does not support above DT parameters.

-- 
Regards
Vignesh


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-24 Thread Lee Jones
On Mon, 24 Oct 2016, John Syne wrote:
> > On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
> >> On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
> >> 
> >> On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
> > On Oct 23, 2016, at 11:02 PM, Mugunthan V N  wrote:
> > 
> > Increase ADC reference clock from 3MHz to 24MHz so that the
> > sampling rates goes up from 100K samples per second to 800K
> > samples per second on AM335x and AM437x SoC.
> > 
> > Also increase opendelay for touchscreen configuration to
> > equalize the increase in ADC reference clock frequency,
> > which results in the same amount touch events reported via
> > evtest on AM335x GP EVM.
> > 
> > Signed-off-by: Mugunthan V N 
> > ---
> > 
> > This patch depends on ADC DMA patch series [1]
> > 
> > Without DMA support, when ADC ref clock is set at 24MHz, I am
> > seeing fifo overflow as CPU is not able to pull the ADC samples.
> > This answers that DMA support is must for ADC to consume the
> > samples generated at 24MHz with no open, step delay or
> > averaging with patch [2].
> > 
> > Measured the performance with the iio_generic_buffer with the
> > patch [3] applied
> > 
> > [1] - http://www.spinics.net/lists/devicetree/msg145045.html
> > [2] - http://pastebin.ubuntu.com/23357935/
> > [3] - http://pastebin.ubuntu.com/23357939/
> > 
> > ---
> > include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
> > b/include/linux/mfd/ti_am335x_tscadc.h
> > index b9a53e0..96c4207 100644
> > --- a/include/linux/mfd/ti_am335x_tscadc.h
> > +++ b/include/linux/mfd/ti_am335x_tscadc.h
> > @@ -90,7 +90,7 @@
> > /* Delay register */
> > #define STEPDELAY_OPEN_MASK (0x3 << 0)
> > #define STEPDELAY_OPEN(val) ((val) << 0)
> > -#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
> >>> Wouldn’t this be better to add this to the devicetree?
> >>> 
> >>>   ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
> >>>   ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
> >>>   ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
> >> 
> >> For a touch screen, there is not need to change in these parameter
> >> settings, so my opinion is to keep it as is. Or am I missing something?
> > I was thinking that if you are using this driver as an ADC, you may want 
> > the flexibility to make these changes in the DT. I’m doing this by 
> > connecting sensors to the ADC inputs. I’m not using this driver for a 
> > touchscreen. 
> 
> Here is a DT overlay were this gets using on the BeagleBoneBlack.  
> 
> https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts
> 
> Besides, these DT features are already implemented in the driver so it is 
> just a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, which 
> you modified in this patch series.

This looks like configuration, no?

DT should be used to describe the hardware.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-24 Thread John Syne

> On Oct 24, 2016, at 11:01 PM, John Syne  wrote:
> 
>> 
>> On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
>> 
>> On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
> On Oct 23, 2016, at 11:02 PM, Mugunthan V N  wrote:
> 
> Increase ADC reference clock from 3MHz to 24MHz so that the
> sampling rates goes up from 100K samples per second to 800K
> samples per second on AM335x and AM437x SoC.
> 
> Also increase opendelay for touchscreen configuration to
> equalize the increase in ADC reference clock frequency,
> which results in the same amount touch events reported via
> evtest on AM335x GP EVM.
> 
> Signed-off-by: Mugunthan V N 
> ---
> 
> This patch depends on ADC DMA patch series [1]
> 
> Without DMA support, when ADC ref clock is set at 24MHz, I am
> seeing fifo overflow as CPU is not able to pull the ADC samples.
> This answers that DMA support is must for ADC to consume the
> samples generated at 24MHz with no open, step delay or
> averaging with patch [2].
> 
> Measured the performance with the iio_generic_buffer with the
> patch [3] applied
> 
> [1] - http://www.spinics.net/lists/devicetree/msg145045.html
> [2] - http://pastebin.ubuntu.com/23357935/
> [3] - http://pastebin.ubuntu.com/23357939/
> 
> ---
> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
> b/include/linux/mfd/ti_am335x_tscadc.h
> index b9a53e0..96c4207 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -90,7 +90,7 @@
> /* Delay register */
> #define STEPDELAY_OPEN_MASK   (0x3 << 0)
> #define STEPDELAY_OPEN(val)   ((val) << 0)
> -#define STEPCONFIG_OPENDLY   STEPDELAY_OPEN(0x098)
>>> Wouldn’t this be better to add this to the devicetree?
>>> 
>>> ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>>> ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
>>> ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
>> 
>> For a touch screen, there is not need to change in these parameter
>> settings, so my opinion is to keep it as is. Or am I missing something?
> I was thinking that if you are using this driver as an ADC, you may want the 
> flexibility to make these changes in the DT. I’m doing this by connecting 
> sensors to the ADC inputs. I’m not using this driver for a touchscreen. 

Here is a DT overlay were this gets using on the BeagleBoneBlack.  

https://github.com/RobertCNelson/bb.org-overlays/blob/master/src/arm/BB-ADC-00A0.dts

Besides, these DT features are already implemented in the driver so it is just 
a matter of adding these entries to the am33xx.dtsi & am4372.dtsi, which you 
modified in this patch series.

Regards,
John

> 
> Regards,
> John
>> 
>> Regards
>> Mugunthan V N



Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-24 Thread John Syne

> On Oct 24, 2016, at 10:52 PM, Mugunthan V N  wrote:
> 
> On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
 On Oct 23, 2016, at 11:02 PM, Mugunthan V N  wrote:
 
 Increase ADC reference clock from 3MHz to 24MHz so that the
 sampling rates goes up from 100K samples per second to 800K
 samples per second on AM335x and AM437x SoC.
 
 Also increase opendelay for touchscreen configuration to
 equalize the increase in ADC reference clock frequency,
 which results in the same amount touch events reported via
 evtest on AM335x GP EVM.
 
 Signed-off-by: Mugunthan V N 
 ---
 
 This patch depends on ADC DMA patch series [1]
 
 Without DMA support, when ADC ref clock is set at 24MHz, I am
 seeing fifo overflow as CPU is not able to pull the ADC samples.
 This answers that DMA support is must for ADC to consume the
 samples generated at 24MHz with no open, step delay or
 averaging with patch [2].
 
 Measured the performance with the iio_generic_buffer with the
 patch [3] applied
 
 [1] - http://www.spinics.net/lists/devicetree/msg145045.html
 [2] - http://pastebin.ubuntu.com/23357935/
 [3] - http://pastebin.ubuntu.com/23357939/
 
 ---
 include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
 
 diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
 b/include/linux/mfd/ti_am335x_tscadc.h
 index b9a53e0..96c4207 100644
 --- a/include/linux/mfd/ti_am335x_tscadc.h
 +++ b/include/linux/mfd/ti_am335x_tscadc.h
 @@ -90,7 +90,7 @@
 /* Delay register */
 #define STEPDELAY_OPEN_MASK(0x3 << 0)
 #define STEPDELAY_OPEN(val)((val) << 0)
 -#define STEPCONFIG_OPENDLYSTEPDELAY_OPEN(0x098)
>> Wouldn’t this be better to add this to the devicetree?
>> 
>>  ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>>  ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
>>  ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;
> 
> For a touch screen, there is not need to change in these parameter
> settings, so my opinion is to keep it as is. Or am I missing something?
I was thinking that if you are using this driver as an ADC, you may want the 
flexibility to make these changes in the DT. I’m doing this by connecting 
sensors to the ADC inputs. I’m not using this driver for a touchscreen. 

Regards,
John
> 
> Regards
> Mugunthan V N



Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-24 Thread Mugunthan V N
On Tuesday 25 October 2016 02:28 AM, John Syne wrote:
>> > On Oct 23, 2016, at 11:02 PM, Mugunthan V N  wrote:
>> > 
>> > Increase ADC reference clock from 3MHz to 24MHz so that the
>> > sampling rates goes up from 100K samples per second to 800K
>> > samples per second on AM335x and AM437x SoC.
>> > 
>> > Also increase opendelay for touchscreen configuration to
>> > equalize the increase in ADC reference clock frequency,
>> > which results in the same amount touch events reported via
>> > evtest on AM335x GP EVM.
>> > 
>> > Signed-off-by: Mugunthan V N 
>> > ---
>> > 
>> > This patch depends on ADC DMA patch series [1]
>> > 
>> > Without DMA support, when ADC ref clock is set at 24MHz, I am
>> > seeing fifo overflow as CPU is not able to pull the ADC samples.
>> > This answers that DMA support is must for ADC to consume the
>> > samples generated at 24MHz with no open, step delay or
>> > averaging with patch [2].
>> > 
>> > Measured the performance with the iio_generic_buffer with the
>> > patch [3] applied
>> > 
>> > [1] - http://www.spinics.net/lists/devicetree/msg145045.html
>> > [2] - http://pastebin.ubuntu.com/23357935/
>> > [3] - http://pastebin.ubuntu.com/23357939/
>> > 
>> > ---
>> > include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
>> > 1 file changed, 2 insertions(+), 2 deletions(-)
>> > 
>> > diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
>> > b/include/linux/mfd/ti_am335x_tscadc.h
>> > index b9a53e0..96c4207 100644
>> > --- a/include/linux/mfd/ti_am335x_tscadc.h
>> > +++ b/include/linux/mfd/ti_am335x_tscadc.h
>> > @@ -90,7 +90,7 @@
>> > /* Delay register */
>> > #define STEPDELAY_OPEN_MASK(0x3 << 0)
>> > #define STEPDELAY_OPEN(val)((val) << 0)
>> > -#define STEPCONFIG_OPENDLYSTEPDELAY_OPEN(0x098)
> Wouldn’t this be better to add this to the devicetree?
> 
>   ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
>   ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
>   ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;

For a touch screen, there is not need to change in these parameter
settings, so my opinion is to keep it as is. Or am I missing something?

Regards
Mugunthan V N


Re: [PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-24 Thread John Syne

> On Oct 23, 2016, at 11:02 PM, Mugunthan V N  wrote:
> 
> Increase ADC reference clock from 3MHz to 24MHz so that the
> sampling rates goes up from 100K samples per second to 800K
> samples per second on AM335x and AM437x SoC.
> 
> Also increase opendelay for touchscreen configuration to
> equalize the increase in ADC reference clock frequency,
> which results in the same amount touch events reported via
> evtest on AM335x GP EVM.
> 
> Signed-off-by: Mugunthan V N 
> ---
> 
> This patch depends on ADC DMA patch series [1]
> 
> Without DMA support, when ADC ref clock is set at 24MHz, I am
> seeing fifo overflow as CPU is not able to pull the ADC samples.
> This answers that DMA support is must for ADC to consume the
> samples generated at 24MHz with no open, step delay or
> averaging with patch [2].
> 
> Measured the performance with the iio_generic_buffer with the
> patch [3] applied
> 
> [1] - http://www.spinics.net/lists/devicetree/msg145045.html
> [2] - http://pastebin.ubuntu.com/23357935/
> [3] - http://pastebin.ubuntu.com/23357939/
> 
> ---
> include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
> b/include/linux/mfd/ti_am335x_tscadc.h
> index b9a53e0..96c4207 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -90,7 +90,7 @@
> /* Delay register */
> #define STEPDELAY_OPEN_MASK   (0x3 << 0)
> #define STEPDELAY_OPEN(val)   ((val) << 0)
> -#define STEPCONFIG_OPENDLY   STEPDELAY_OPEN(0x098)
Wouldn’t this be better to add this to the devicetree?

ti,chan-step-avg = <0x16 0x16 0x16 0x16 0x16 0x16 0x16>;
ti,chan-step-opendelay = <0x500 0x500 0x500 0x500 0x500 0x500 0x500>;
ti,chan-step-sampledelay = <0x0 0x0 0x0 0x0 0x0 0x0 0x0>;

Regards,
John
> +#define STEPCONFIG_OPENDLY   STEPDELAY_OPEN(0x500)
> #define STEPDELAY_SAMPLE_MASK (0xFF << 24)
> #define STEPDELAY_SAMPLE(val) ((val) << 24)
> #define STEPCONFIG_SAMPLEDLY  STEPDELAY_SAMPLE(0)
> @@ -137,7 +137,7 @@
> #define SEQ_STATUS BIT(5)
> #define CHARGE_STEP   0x11
> 
> -#define ADC_CLK  300
> +#define ADC_CLK  2400
> #define TOTAL_STEPS   16
> #define TOTAL_CHANNELS8
> #define FIFO1_THRESHOLD   19
> -- 
> 2.10.1.502.g6598894
> 



[PATCH] drivers: mfd: ti_am335x_tscadc: increase ADC ref clock to 24MHz

2016-10-23 Thread Mugunthan V N
Increase ADC reference clock from 3MHz to 24MHz so that the
sampling rates goes up from 100K samples per second to 800K
samples per second on AM335x and AM437x SoC.

Also increase opendelay for touchscreen configuration to
equalize the increase in ADC reference clock frequency,
which results in the same amount touch events reported via
evtest on AM335x GP EVM.

Signed-off-by: Mugunthan V N 
---

This patch depends on ADC DMA patch series [1]

Without DMA support, when ADC ref clock is set at 24MHz, I am
seeing fifo overflow as CPU is not able to pull the ADC samples.
This answers that DMA support is must for ADC to consume the
samples generated at 24MHz with no open, step delay or
averaging with patch [2].

Measured the performance with the iio_generic_buffer with the
patch [3] applied

[1] - http://www.spinics.net/lists/devicetree/msg145045.html
[2] - http://pastebin.ubuntu.com/23357935/
[3] - http://pastebin.ubuntu.com/23357939/

---
 include/linux/mfd/ti_am335x_tscadc.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/mfd/ti_am335x_tscadc.h 
b/include/linux/mfd/ti_am335x_tscadc.h
index b9a53e0..96c4207 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -90,7 +90,7 @@
 /* Delay register */
 #define STEPDELAY_OPEN_MASK(0x3 << 0)
 #define STEPDELAY_OPEN(val)((val) << 0)
-#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x098)
+#define STEPCONFIG_OPENDLY STEPDELAY_OPEN(0x500)
 #define STEPDELAY_SAMPLE_MASK  (0xFF << 24)
 #define STEPDELAY_SAMPLE(val)  ((val) << 24)
 #define STEPCONFIG_SAMPLEDLY   STEPDELAY_SAMPLE(0)
@@ -137,7 +137,7 @@
 #define SEQ_STATUS BIT(5)
 #define CHARGE_STEP0x11
 
-#define ADC_CLK300
+#define ADC_CLK2400
 #define TOTAL_STEPS16
 #define TOTAL_CHANNELS 8
 #define FIFO1_THRESHOLD19
-- 
2.10.1.502.g6598894