From: Sean Paul <sean@poorly.run>
To: Douglas Anderson <dianders@chromium.org>
Cc: Sean Paul <seanpaul@chromium.org>,
Thierry Reding <thierry.reding@gmail.com>,
Sandeep Panda <spanda@codeaurora.org>,
linux-arm-msm@vger.kernel.org,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
jsanka@codeaurora.org, ryandcase@chromium.org,
David Airlie <airlied@linux.ie>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/6] drm/panel: simple: Support panels with HPD where HPD isn't connected
Date: Thu, 25 Oct 2018 14:08:33 -0400 [thread overview]
Message-ID: <20181025180833.GK154160@art_vandelay> (raw)
In-Reply-To: <20181022204639.8558-2-dianders@chromium.org>
On Mon, Oct 22, 2018 at 01:46:35PM -0700, Douglas Anderson wrote:
> Some eDP panels that are designed to be always connected to a board
> use their HPD signal to signal that they've finished powering on and
> they're ready to be talked to.
>
> However, for various reasons it's possible that the HPD signal from
> the panel isn't actually hooked up. In the case where the HPD isn't
> hooked up you can look at the timing diagram on the panel datasheet
> and insert a delay for the maximum amount of time that the HPD might
> take to come up.
>
> Let's add support in simple-panel for this concept.
>
> At the moment we will co-opt the existing "prepare" delay to keep
> track of the delay and we'll use a boolean to specify that a given
> panel should only apply the delay if the "no-hpd" property was
> specified.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
> drivers/gpu/drm/panel/panel-simple.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 97964f7f2ace..38c646fb55fd 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -63,12 +63,15 @@ struct panel_desc {
> * turn the display off (no content is visible)
> * @unprepare: the time (in milliseconds) that it takes for the panel
> * to power itself down completely
> + * @prepare_delay_only_if_no_hpd: The prepare delay should only be done
> + * if we know Hot Plug Detect isn't used.
I think it'd be more clear if we just had a new 'hpd_absent_delay' which is
added to prepare if no_hpd is true.
Sean
> */
> struct {
> unsigned int prepare;
> unsigned int enable;
> unsigned int disable;
> unsigned int unprepare;
> + bool prepare_delay_only_if_no_hpd;
> } delay;
>
> u32 bus_format;
> @@ -79,6 +82,7 @@ struct panel_simple {
> struct drm_panel base;
> bool prepared;
> bool enabled;
> + bool no_hpd;
>
> const struct panel_desc *desc;
>
> @@ -215,7 +219,8 @@ static int panel_simple_prepare(struct drm_panel *panel)
>
> gpiod_set_value_cansleep(p->enable_gpio, 1);
>
> - if (p->desc->delay.prepare)
> + if (p->desc->delay.prepare &&
> + (!p->desc->delay.prepare_delay_only_if_no_hpd || p->no_hpd))
> msleep(p->desc->delay.prepare);
>
> p->prepared = true;
> @@ -305,6 +310,8 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
> panel->prepared = false;
> panel->desc = desc;
>
> + panel->no_hpd = of_property_read_bool(dev->of_node, "no-hpd");
> +
> panel->supply = devm_regulator_get(dev, "power");
> if (IS_ERR(panel->supply))
> return PTR_ERR(panel->supply);
> --
> 2.19.1.568.g152ad8e336-goog
>
--
Sean Paul, Software Engineer, Google / Chromium OS
next prev parent reply other threads:[~2018-10-25 18:08 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-22 20:46 [PATCH 1/6] dt-bindings: drm/panel: simple: Add no-hpd property Douglas Anderson
2018-10-22 20:46 ` [PATCH 2/6] drm/panel: simple: Support panels with HPD where HPD isn't connected Douglas Anderson
2018-10-25 18:08 ` Sean Paul [this message]
2018-10-22 20:46 ` [PATCH 3/6] drm/panel: simple: Add "no-hpd" delay for Innolux TV123WAM Douglas Anderson
2018-10-22 20:46 ` [PATCH 4/6] drm/bridge: ti-sn65dsi86: Remove the mystery delay Douglas Anderson
2018-10-25 18:10 ` Sean Paul
2018-10-22 20:46 ` [PATCH 5/6] drm/panel: simple: Innolux TV123WAM is actually P120ZDG-BF1 Douglas Anderson
2018-10-25 18:13 ` Sean Paul
2018-10-25 18:45 ` Doug Anderson
2018-10-25 19:25 ` Abhinav Kumar
2018-10-25 22:24 ` Doug Anderson
2018-10-26 14:38 ` Sean Paul
2018-10-22 20:46 ` [PATCH 6/6] dt-bindings: " Douglas Anderson
2018-10-25 18:15 ` Sean Paul
2018-10-25 19:49 ` Rob Herring
2018-10-25 18:06 ` [PATCH 1/6] dt-bindings: drm/panel: simple: Add no-hpd property Sean Paul
2018-10-25 19:28 ` Rob Herring
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