From: Doug Anderson <dianders@chromium.org>
To: Rajeev Nandan <rajeevny@codeaurora.org>
Cc: dri-devel <dri-devel@lists.freedesktop.org>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
freedreno <freedreno@lists.freedesktop.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Thierry Reding <thierry.reding@gmail.com>,
Sam Ravnborg <sam@ravnborg.org>, Rob Clark <robdclark@gmail.com>,
Lyude Paul <lyude@redhat.com>,
Jani Nikula <jani.nikula@intel.com>,
Rob Herring <robh@kernel.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Andrzej Hajda <a.hajda@samsung.com>,
Daniel Thompson <daniel.thompson@linaro.org>,
"Kristian H. Kristensen" <hoegsberg@chromium.org>,
Abhinav Kumar <abhinavk@codeaurora.org>,
Sean Paul <seanpaul@chromium.org>,
Kalyan Thota <kalyan_t@codeaurora.org>,
Krishna Manikandan <mkrishn@codeaurora.org>
Subject: Re: [v5 3/5] drm/panel-simple: Support for delays between GPIO & regulator
Date: Wed, 2 Jun 2021 17:05:42 -0700 [thread overview]
Message-ID: <CAD=FV=UncbMRcrJmMiCNT6YSoSGzENnmwfEBqmV2aEGXO5mA+Q@mail.gmail.com> (raw)
In-Reply-To: <1622390172-31368-4-git-send-email-rajeevny@codeaurora.org>
Hi,
On Sun, May 30, 2021 at 8:57 AM Rajeev Nandan <rajeevny@codeaurora.org> wrote:
>
> Some panels datasheets may specify a delay between the enable GPIO and
> the regulator. Support this in panel-simple.
>
> Signed-off-by: Rajeev Nandan <rajeevny@codeaurora.org>
> ---
>
> Changes in v4:
> - New
>
> Changes in v5:
> - Update description (Douglas)
> - Warn if "power_to_enable" or "disable_to_power_off" is non-zero and panel->enable_gpio
> is NULL (Douglas)
>
> drivers/gpu/drm/panel/panel-simple.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 047fad5..e3f5b7e 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -133,6 +133,22 @@ struct panel_desc {
> unsigned int prepare_to_enable;
>
> /**
> + * @delay.power_to_enable: Time for the power to enable the display on.
> + *
> + * The time (in milliseconds) to wait after powering up the display
> + * before asserting its enable pin.
> + */
> + unsigned int power_to_enable;
> +
> + /**
> + * @delay.disable_to_power_off: Time for the disable to power the display off.
> + *
> + * The time (in milliseconds) to wait before powering off the display
> + * after deasserting its enable pin.
> + */
> + unsigned int disable_to_power_off;
> +
> + /**
> * @delay.enable: Time for the panel to display a valid frame.
> *
> * The time (in milliseconds) that it takes for the panel to
> @@ -347,6 +363,10 @@ static int panel_simple_suspend(struct device *dev)
> struct panel_simple *p = dev_get_drvdata(dev);
>
> gpiod_set_value_cansleep(p->enable_gpio, 0);
> +
> + if (p->desc->delay.disable_to_power_off)
> + msleep(p->desc->delay.disable_to_power_off);
> +
> regulator_disable(p->supply);
> p->unprepared_time = ktime_get();
>
> @@ -407,6 +427,9 @@ static int panel_simple_prepare_once(struct panel_simple *p)
> return err;
> }
>
> + if (p->desc->delay.power_to_enable)
> + msleep(p->desc->delay.power_to_enable);
> +
> gpiod_set_value_cansleep(p->enable_gpio, 1);
>
> delay = p->desc->delay.prepare;
> @@ -782,6 +805,11 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc,
> break;
> }
>
> + if (!panel->enable_gpio && desc->delay.disable_to_power_off)
> + dev_warn(dev, "Specify enable_gpio when using disable_to_power_off delay\n");
> + if (!panel->enable_gpio && desc->delay.power_to_enable)
> + dev_warn(dev, "Specify enable_gpio when using power_to_enable delay\n");
Last nit is that the warning messages could be a little confusing to
someone reading the logs. I guess the target audience of the error
message is probably someone doing bringup. That person specified a
panel in their device tree and maybe isn't even aware that they're
using "disable_to_power_off" or "power_to_enable". Maybe wording
instead:
Need a delay after disabling panel GPIO, but a GPIO wasn't provided.
Need a delay after enabling panel GPIO, but a GPIO wasn't provided.
That's definitely getting into nittiness, though and I wouldn't be
upset if the patch landed with the existing messages. Thus, with or
without the change to the error message:
Reviewed-by: Douglas Anderson <dianders@chromium.org>
next prev parent reply other threads:[~2021-06-03 0:07 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-30 15:56 [v5 0/5] drm: Support basic DPCD backlight in panel-simple and add a new panel ATNA33XC20 Rajeev Nandan
2021-05-30 15:56 ` [v5 1/5] drm/panel: add basic DP AUX backlight support Rajeev Nandan
2021-05-30 18:49 ` kernel test robot
2021-05-30 18:52 ` kernel test robot
2021-06-03 0:05 ` Doug Anderson
2021-06-03 6:26 ` rajeevny
2021-05-30 15:56 ` [v5 2/5] drm/panel-simple: Support DP AUX backlight Rajeev Nandan
2021-05-30 19:25 ` kernel test robot
2021-06-03 0:05 ` Doug Anderson
2021-05-30 15:56 ` [v5 3/5] drm/panel-simple: Support for delays between GPIO & regulator Rajeev Nandan
2021-06-03 0:05 ` Doug Anderson [this message]
2021-05-30 15:56 ` [v5 4/5] dt-bindings: display: simple: Add Samsung ATNA33XC20 Rajeev Nandan
2021-06-02 18:34 ` Rob Herring
2021-05-30 15:56 ` [v5 5/5] drm/panel-simple: " Rajeev Nandan
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