Re: [v4 2/4] drm/panel-simple: Support for delays between GPIO & regulator
From: Doug Anderson <dianders@chromium.org>
Date: 2021-05-25 17:19:05
Also in:
dri-devel, linux-arm-msm, lkml
Hi, On Tue, May 25, 2021 at 12:31 AM Rajeev Nandan [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Some panels datasheets may specify a delay between the enable GPIO and the regulator. Support this in panel-simple. Signed-off-by: Rajeev Nandan <redacted> --- Changes in v4: - New drivers/gpu/drm/panel/panel-simple.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c index f9e4e60..caed71b 100644 --- a/drivers/gpu/drm/panel/panel-simple.c +++ b/drivers/gpu/drm/panel/panel-simple.c@@ -134,6 +134,22 @@ 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) that it takes for the panel to + * turn the display on.
Maybe a slightly better description: 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) that it takes for the panel to + * turn the display off.
Maybe a slightly better description: The time (in milliseconds) to wait after disabling the display before deasserting its enable pin.
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+ */ + 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@@ -367,6 +383,10 @@ 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); +
I wonder if it's worth a warning if "p->desc->delay.disable_to_power_off" is non-zero and p->enable_gpio is NULL? I guess in theory it'd also be nice to confirm that p->supply wasn't a dummy regulator, but that's slightly harder.
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regulator_disable(p->supply); p->unprepared_time = ktime_get();@@ -427,6 +447,9 @@ 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); +
Similar to above: I wonder if it's worth a warning if "p->desc->delay.power_to_enable" is non-zero and p->enable_gpio is NULL? -Doug