linux-kernel - Re: [PATCH] media: i2c: tvp5150: fix color burst lock instability on some hardware

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Message-ID: <20180326064353.187f752c@vento.lan>
Date:   Mon, 26 Mar 2018 06:43:53 -0300
From:   Mauro Carvalho Chehab <mchehab@...nel.org>
To:     Nasser Afshin <afshin.nasser@...il.com>
Cc:     p.zabel@...gutronix.de, sakari.ailus@...ux.intel.com,
        hans.verkuil@...co.com, bparrot@...com, garsilva@...eddedor.com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: i2c: tvp5150: fix color burst lock instability
 on some hardware

Hi Nasser,

Em Mon, 26 Mar 2018 03:26:33 +0430
Nasser Afshin <afshin.nasser@...il.com> escreveu:

> According to the datasheet, INTREQ/GPCL/VBLK should have a pull-up/down
> resistor if it's been disabled. On hardware that does not have such
> resistor, we should use the default output enable value.
> This prevents the color burst lock instability problem.

If this is hardware-dependent, you should instead store it at
OF (for SoC) or pass via platform_data (for PCI/USB devices).

> 
> Signed-off-by: Nasser Afshin <Afshin.Nasser@...il.com>
> ---
>  drivers/media/i2c/tvp5150.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/i2c/tvp5150.c b/drivers/media/i2c/tvp5150.c
> index 2476d812f669..0e9713814816 100644
> --- a/drivers/media/i2c/tvp5150.c
> +++ b/drivers/media/i2c/tvp5150.c
> @@ -328,7 +328,7 @@ static const struct i2c_reg_value tvp5150_init_default[] = {
>  		TVP5150_OP_MODE_CTL,0x00
>  	},
>  	{ /* 0x03 */
> -		TVP5150_MISC_CTL,0x01
> +		TVP5150_MISC_CTL,0x21
>  	},
>  	{ /* 0x06 */
>  		TVP5150_COLOR_KIL_THSH_CTL,0x10
> @@ -1072,7 +1072,8 @@ static int tvp5150_s_stream(struct v4l2_subdev *sd, int enable)
>  		 * Enable the YCbCr and clock outputs. In discrete sync mode
>  		 * (non-BT.656) additionally enable the the sync outputs.
>  		 */
> -		val |= TVP5150_MISC_CTL_YCBCR_OE | TVP5150_MISC_CTL_CLOCK_OE;
> +		val |= TVP5150_MISC_CTL_YCBCR_OE | TVP5150_MISC_CTL_CLOCK_OE |
> +			TVP5150_MISC_CTL_INTREQ_OE;
>  		if (decoder->mbus_type == V4L2_MBUS_PARALLEL)
>  			val |= TVP5150_MISC_CTL_SYNC_OE;
>  	}



Thanks,
Mauro