linux-kernel - Re: [PATCH v3 3/9] media: adv7180: add support for NEWAVMODE

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Date:	Mon, 25 Jul 2016 10:55:09 -0700
From:	Steve Longerbeam <steve_longerbeam@...tor.com>
To:	Ian Arkver <ian.arkver.dev@...il.com>,
	Steve Longerbeam <slongerbeam@...il.com>, <lars@...afoo.de>
CC:	<mchehab@...nel.org>, <linux-media@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 3/9] media: adv7180: add support for NEWAVMODE

On 07/25/2016 05:04 AM, Ian Arkver wrote:
> On 23/07/16 18:00, Steve Longerbeam wrote:
>> Parse the optional v4l2 endpoint DT node. If the bus type is
>> V4L2_MBUS_BT656 and the endpoint node specifies "newavmode",
>> configure the BT.656 bus in NEWAVMODE.
>>
>> Signed-off-by: Steve Longerbeam <steve_longerbeam@...tor.com>
>>
>> ---
>>
>> v3:
>> - the newavmode endpoint property is now private to adv7180.
>> ---
>>  .../devicetree/bindings/media/i2c/adv7180.txt      |  4 ++
>>  drivers/media/i2c/adv7180.c                        | 46 ++++++++++++++++++++--
>>  2 files changed, 47 insertions(+), 3 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/media/i2c/adv7180.txt b/Documentation/devicetree/bindings/media/i2c/adv7180.txt
>> index 0d50115..6c175d2 100644
>> --- a/Documentation/devicetree/bindings/media/i2c/adv7180.txt
>> +++ b/Documentation/devicetree/bindings/media/i2c/adv7180.txt
>> @@ -15,6 +15,10 @@ Required Properties :
>>  		"adi,adv7282"
>>  		"adi,adv7282-m"
>>  
>> +Optional Endpoint Properties :
>> +- newavmode: a boolean property to indicate the BT.656 bus is operating
>> +  in Analog Device's NEWAVMODE. Valid for BT.656 busses only.
>> +
>>  Example:
>>  
>>  	i2c0@...2000 {
>> diff --git a/drivers/media/i2c/adv7180.c b/drivers/media/i2c/adv7180.c
>> index cb83ebb..3067d5f 100644
>> --- a/drivers/media/i2c/adv7180.c
>> +++ b/drivers/media/i2c/adv7180.c
>> @@ -31,6 +31,7 @@
>>  #include <media/v4l2-event.h>
>>  #include <media/v4l2-device.h>
>>  #include <media/v4l2-ctrls.h>
>> +#include <media/v4l2-of.h>
>>  #include <linux/mutex.h>
>>  #include <linux/delay.h>
>>  
>> @@ -106,6 +107,7 @@
>>  #define ADV7180_REG_SHAP_FILTER_CTL_1	0x0017
>>  #define ADV7180_REG_CTRL_2		0x001d
>>  #define ADV7180_REG_VSYNC_FIELD_CTL_1	0x0031
>> +#define ADV7180_VSYNC_FIELD_CTL_1_NEWAVMODE 0x02
>
> See below re this value.
>

Hi Ian, I double-checked the ADV7180 datasheet, this value is
correct. Bit 4, when cleared, _enables_ NEWAVMODE.


>>  #define ADV7180_REG_MANUAL_WIN_CTL_1	0x003d
>>  #define ADV7180_REG_MANUAL_WIN_CTL_2	0x003e
>>  #define ADV7180_REG_MANUAL_WIN_CTL_3	0x003f
>> @@ -214,6 +216,7 @@ struct adv7180_state {
>>  	struct mutex		mutex; /* mutual excl. when accessing chip */
>>  	int			irq;
>>  	v4l2_std_id		curr_norm;
>> +	bool			newavmode;
>>  	bool			powered;
>>  	bool			streaming;
>>  	u8			input;
>> @@ -864,9 +867,15 @@ static int adv7180_init(struct adv7180_state *state)
>>  	if (ret < 0)
>>  		return ret;
>>  
>> -	/* Manually set V bit end position in NTSC mode */
>> -	return adv7180_write(state, ADV7180_REG_NTSC_V_BIT_END,
>> -					ADV7180_NTSC_V_BIT_END_MANUAL_NVEND);
>> +	if (!state->newavmode) {
>> +		/* Manually set V bit end position in NTSC mode */
>> +		ret = adv7180_write(state, ADV7180_REG_NTSC_V_BIT_END,
>> +				    ADV7180_NTSC_V_BIT_END_MANUAL_NVEND);
>> +		if (ret < 0)
>> +			return ret;
>> +	}
>> +
>> +	return 0;
>
> According to the ADV7180 datasheet, rev. J, page 48 [1], when NEWAVMODE is 0,
> no adjustments are possible to the output timings, which would imply this write
> is ignored after your edit.

That's correct, when NEWAVMODE is enabled (by clearing reg 0x31 bit 4), no
adjustments are possible to the output timings:

>From the rev J datasheet, page 91, when reg 0x31 bit 4 is set (NEAVMODE disabled):

"Manual VS/FIELD position controlled by Register 0x32, Register 0x33, and
Register 0xE5 to Register 0xEA"

>
> 1: www.analog.com/media/en/technical-documentation/data-sheets/*ADV7180*.pdf
>
>>  }
>>  
>>  static int adv7180_set_std(struct adv7180_state *state, unsigned int std)
>> @@ -1217,6 +1226,13 @@ static int init_device(struct adv7180_state *state)
>>  	if (ret)
>>  		goto out_unlock;
>>  
>> +	if (state->newavmode) {
>> +		ret = adv7180_write(state, ADV7180_REG_VSYNC_FIELD_CTL_1,
>> +				    ADV7180_VSYNC_FIELD_CTL_1_NEWAVMODE);
>> +		if (ret < 0)
>> +			goto out_unlock;
>> +	}
>> +
>
> Again according to the DS, NEWAVMODE is set by default and enables a
> stream which is by default CCIR656 compliant. Your edit writes 0x02 to
> this register which actually clears NEWAVMODE (bit 4).

correct, it clears bit 4 which _enables_ NEWAVMODE.

NEWAVMODE by default is _disabled_ (bit 4 is set).


Steve