Re: [PATCH] [media] adv7604: Initialize drive strength to default when using DT

["Niklas Söderlund" <niklas.soderlund@ragnatech.se>]

Hi Lars,

On 2016-11-29 12:23:48 +0100, Lars-Peter Clausen wrote:
> The adv7604 driver platform data contains fields for configuring the drive
> strength of the output pins. When probing the driver through DT these
> fields are not explicitly initialized, which means they are left at 0. This
> is a reserved setting for the drive strength configuration though and can
> cause signal integrity issues.
> 
> Whether these signal integrity issues are visible depends on the PCB
> specifics (e.g. the higher the load capacitance for the output the more
> visible the issue). But it has been observed on existing solutions at high
> pixel clock rates.
> 
> Initialize the drive strength settings to the power-on-reset value of the
> device when probing through devicetree to avoid this issue.
> 
> Fixes: 0e158be0162b ("adv7604: Add DT support")
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

Tested on Renesas Koelsch board which uses a adv7612 for HDMI input.

Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  drivers/media/i2c/adv7604.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c
> index 5630eb2..a4dc64a 100644
> --- a/drivers/media/i2c/adv7604.c
> +++ b/drivers/media/i2c/adv7604.c
> @@ -3132,6 +3132,9 @@ static int adv76xx_parse_dt(struct adv76xx_state *state)
>  	state->pdata.blank_data = 1;
>  	state->pdata.op_format_mode_sel = ADV7604_OP_FORMAT_MODE0;
>  	state->pdata.bus_order = ADV7604_BUS_ORDER_RGB;
> +	state->pdata.dr_str_data = ADV76XX_DR_STR_MEDIUM_HIGH;
> +	state->pdata.dr_str_clk = ADV76XX_DR_STR_MEDIUM_HIGH;
> +	state->pdata.dr_str_sync = ADV76XX_DR_STR_MEDIUM_HIGH;
>  
>  	return 0;
>  }
> -- 
> 2.1.4
> 

-- 
Regards,
Niklas Söderlund