Re: [PATCH] media: adv748x: Don't disable CSI-2 on link_setup

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

On Wed, Mar 06, 2019 at 12:26:59PM +0100, Jacopo Mondi wrote:
> When both the media links between AFE and HDMI and the two TX CSI-2 outputs
> gets disabled, the routing register ADV748X_IO_10 gets zeroed causing both
> TXA and TXB output to get disabled.
> 
> This causes some HDMI transmitters to stop working after both AFE and
> HDMI links are disabled.

Could you elaborate on why this would be the case ? By HDMI transmitter,
I assume you mean the device connected to the HDMI input of the ADV748x.
Why makes it fail (and how ?) when the TXA and TXB are both disabled ?

> Fix this by preventing writing 0 to
> ADV748X_IO_10 register, which gets only updated when links are enabled
> again.
> 
> Fixes: 9423ca350df7 ("media: adv748x: Implement TX link_setup callback")
> Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
> The issue presents itself only on some HDMI transmitters, and went unnoticed
> during the development of:
> "[PATCH v3 0/6] media: adv748x: Implement dynamic routing support"
> 
> Patch intended to be applied on top of latest media-master, where the
> "[PATCH v3 0/6] media: adv748x: Implement dynamic routing support"
> series is applied.
> 
> The patch reports a "Fixes" tag, but should actually be merged with the above
> mentioned series.
> 
> ---
>  drivers/media/i2c/adv748x/adv748x-core.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/i2c/adv748x/adv748x-core.c b/drivers/media/i2c/adv748x/adv748x-core.c
> index f57cd77a32fa..0e5a75eb6d75 100644
> --- a/drivers/media/i2c/adv748x/adv748x-core.c
> +++ b/drivers/media/i2c/adv748x/adv748x-core.c
> @@ -354,6 +354,9 @@ static int adv748x_link_setup(struct media_entity *entity,
> 
>  	tx->src = enable ? rsd : NULL;
> 
> +	if (!enable)
> +		return 0;
> +
>  	if (state->afe.tx) {
>  		/* AFE Requires TXA enabled, even when output to TXB */
>  		io10 |= ADV748X_IO_10_CSI4_EN;

-- 
Regards,

Laurent Pinchart