Re: [RFC PATCH 3/3] encoder-tpd12s015: keep the ls_oe_gpio on while the phys_addr is valid

From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Hans Verkuil <hverkuil@xs4all.nl>, linux-media@vger.kernel.org
Cc: Hans Verkuil <hans.verkuil@cisco.com>, dri-devel@lists.freedesktop.org
Subject: Re: [RFC PATCH 3/3] encoder-tpd12s015: keep the ls_oe_gpio on while the phys_addr is valid
Date: Tue, 10 May 2016 14:36:50 +0300	[thread overview]
Message-ID: <5731C7D2.4090807@ti.com> (raw)
In-Reply-To: <1461922746-17521-4-git-send-email-hverkuil@xs4all.nl>

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Hi Hans,

On 29/04/16 12:39, Hans Verkuil wrote:
> From: Hans Verkuil <hans.verkuil@cisco.com>
> 
> As long as there is a valid physical address in the EDID and the omap
> CEC support is enabled, then we keep ls_oe_gpio on to ensure the CEC
> signal is passed through the tpd12s015.
> 
> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> Suggested-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> ---
>  drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c b/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
> index 916a899..efbba23 100644
> --- a/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
> +++ b/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
> @@ -16,6 +16,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/gpio/consumer.h>
>  
> +#include <media/cec-edid.h>
>  #include <video/omapdss.h>
>  #include <video/omap-panel-data.h>
>  
> @@ -65,6 +66,7 @@ static void tpd_disconnect(struct omap_dss_device *dssdev,
>  		return;
>  
>  	gpiod_set_value_cansleep(ddata->ct_cp_hpd_gpio, 0);
> +	gpiod_set_value_cansleep(ddata->ls_oe_gpio, 0);
>  
>  	dst->src = NULL;
>  	dssdev->dst = NULL;
> @@ -142,6 +144,7 @@ static int tpd_read_edid(struct omap_dss_device *dssdev,
>  {
>  	struct panel_drv_data *ddata = to_panel_data(dssdev);
>  	struct omap_dss_device *in = ddata->in;
> +	bool valid_phys_addr = 0;
>  	int r;
>  
>  	if (!gpiod_get_value_cansleep(ddata->hpd_gpio))
> @@ -151,7 +154,15 @@ static int tpd_read_edid(struct omap_dss_device *dssdev,
>  
>  	r = in->ops.hdmi->read_edid(in, edid, len);
>  
> -	gpiod_set_value_cansleep(ddata->ls_oe_gpio, 0);
> +#ifdef CONFIG_OMAP2_DSS_HDMI_CEC
> +	/*
> +	 * In order to support CEC this pin should remain high
> +	 * as long as the EDID has a valid physical address.
> +	 */
> +	valid_phys_addr =
> +		cec_get_edid_phys_addr(edid, r, NULL) != CEC_PHYS_ADDR_INVALID;
> +#endif
> +	gpiod_set_value_cansleep(ddata->ls_oe_gpio, valid_phys_addr);
>  
>  	return r;
>  }

I think this works, but... Maybe it would be cleaner to have the LS_OE
enabled if a cable is connected. That's actually what we had earlier,
but I removed that due to a race issue:

a87a6d6b09de3118e5679c2057b99b7791b7673b ("OMAPDSS: encoder-tpd12s015:
Fix race issue with LS_OE"). Now, with CEC, there's need to have LS_OE
enabled even after reading the EDID, so I think it's better to go back
to the old model (after fixing the race issue, of course =).

 Tomi

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