Re: [PATCH 2/8] omapdrm: encoder-tpd12s015: keep ls_oe_gpio high if CEC is enabled

[Tomi Valkeinen]

On 14/04/17 13:25, Hans Verkuil wrote:
> From: Hans Verkuil 
> 
> When the OMAP4 CEC support is enabled the CEC pin should always
> be on. So keep ls_oe_gpio high when CONFIG_OMAP4_DSS_HDMI_CEC
> is set.
> 
> Background: even if the HPD is low it should still be possible
> to use CEC. Some displays will set the HPD low when they go into standby or
> when they switch to another input, but CEC is still available and able
> to wake up/change input for such a display.
> 
> This is explicitly allowed by the CEC standard.
> 
> Signed-off-by: Hans Verkuil 
> ---
>  drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c | 8 
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c 
> b/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
> index 58276a48112e..757554e6d62f 100644
> --- a/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
> +++ b/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
> @@ -46,6 +46,9 @@ static int tpd_connect(struct omap_dss_device *dssdev,
>   dssdev->dst = dst;
>  
>   gpiod_set_value_cansleep(ddata->ct_cp_hpd_gpio, 1);
> +#ifdef CONFIG_OMAP4_DSS_HDMI_CEC
> + gpiod_set_value_cansleep(ddata->ls_oe_gpio, 1);
> +#endif
>   /* DC-DC converter needs at max 300us to get to 90% of 5V */
>   udelay(300);
>  
> @@ -64,6 +67,7 @@ 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;
> @@ -146,11 +150,15 @@ static int tpd_read_edid(struct omap_dss_device *dssdev,
>   if (!gpiod_get_value_cansleep(ddata->hpd_gpio))
>   return -ENODEV;
>  
> +#ifndef CONFIG_OMAP4_DSS_HDMI_CEC
>   gpiod_set_value_cansleep(ddata->ls_oe_gpio, 1);
> +#endif
>  
>   r = in->ops.hdmi->read_edid(in, edid, len);
>  
> +#ifndef CONFIG_OMAP4_DSS_HDMI_CEC
>   gpiod_set_value_cansleep(ddata->ls_oe_gpio, 0);
> +#endif
>  
>   return r;
>  }
> 

Optimally, we want to enable LS_OE only when needed, which would be when
reading EDID, using HDCP, or using CEC. But we don't have good means to
convey that information at the moment, and I'd rather leave it for later
when we have done the bigger restructuring of omapdrm.

For now, instead of the ifdef-confusion, I think we should just enable
the LS_OE in tpd_connect and be done with it.

 Tomi



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[PATCH 2/8] omapdrm: encoder-tpd12s015: keep ls_oe_gpio high if CEC is enabled

[Hans Verkuil]

From: Hans Verkuil 

When the OMAP4 CEC support is enabled the CEC pin should always
be on. So keep ls_oe_gpio high when CONFIG_OMAP4_DSS_HDMI_CEC
is set.

Background: even if the HPD is low it should still be possible
to use CEC. Some displays will set the HPD low when they go into standby or
when they switch to another input, but CEC is still available and able
to wake up/change input for such a display.

This is explicitly allowed by the CEC standard.

Signed-off-by: Hans Verkuil 
---
 drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c | 8 
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c 
b/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
index 58276a48112e..757554e6d62f 100644
--- a/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
+++ b/drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c
@@ -46,6 +46,9 @@ static int tpd_connect(struct omap_dss_device *dssdev,
dssdev->dst = dst;
 
gpiod_set_value_cansleep(ddata->ct_cp_hpd_gpio, 1);
+#ifdef CONFIG_OMAP4_DSS_HDMI_CEC
+   gpiod_set_value_cansleep(ddata->ls_oe_gpio, 1);
+#endif
/* DC-DC converter needs at max 300us to get to 90% of 5V */
udelay(300);
 
@@ -64,6 +67,7 @@ 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;
@@ -146,11 +150,15 @@ static int tpd_read_edid(struct omap_dss_device *dssdev,
if (!gpiod_get_value_cansleep(ddata->hpd_gpio))
return -ENODEV;
 
+#ifndef CONFIG_OMAP4_DSS_HDMI_CEC
gpiod_set_value_cansleep(ddata->ls_oe_gpio, 1);
+#endif
 
r = in->ops.hdmi->read_edid(in, edid, len);
 
+#ifndef CONFIG_OMAP4_DSS_HDMI_CEC
gpiod_set_value_cansleep(ddata->ls_oe_gpio, 0);
+#endif
 
return r;
 }
-- 
2.11.0