Re: [PATCH 4/5] fbdev: omap2: panel-dpi: allow specification of a reset gpio
From: Tomi Valkeinen <hidden>
Date: 2015-12-16 17:35:30
On 10/12/15 15:11, Uwe Kleine-König wrote:
From: Uwe Kleine-König <redacted> Some displays have a reset input. To assert that the display is functional the reset gpio must be deasserted. Teach the driver to get and drive such a gpio accordingly. Signed-off-by: Uwe Kleine-König <redacted> --- Documentation/devicetree/bindings/video/panel-dpi.txt | 1 + drivers/video/fbdev/omap2/displays-new/panel-dpi.c | 7 +++++++ 2 files changed, 8 insertions(+)
DT changes should be posted to devicetree@vger.kernel.org. And, I think, the binding document changes are usually as a separate patch.
quoted hunk ↗ jump to hunk
diff --git a/Documentation/devicetree/bindings/video/panel-dpi.txt b/Documentation/devicetree/bindings/video/panel-dpi.txt index a40180b05bab..1a1d8f6f884f 100644 --- a/Documentation/devicetree/bindings/video/panel-dpi.txt +++ b/Documentation/devicetree/bindings/video/panel-dpi.txt@@ -7,6 +7,7 @@ Required properties: Optional properties: - label: a symbolic name for the panel - enable-gpios: panel enable gpio +- reset-gpios: GPIO to control the RESET pin Required nodes: - "panel-timing" containing video timingsdiff --git a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c index 1216341a0d19..7e2f9e0813dc 100644 --- a/drivers/video/fbdev/omap2/displays-new/panel-dpi.c +++ b/drivers/video/fbdev/omap2/displays-new/panel-dpi.c@@ -32,6 +32,7 @@ struct panel_drv_data { int backlight_gpio; struct gpio_desc *enable_gpio; + struct gpio_desc *reset_gpio; }; #define to_panel_data(p) container_of(p, struct panel_drv_data, dssdev)@@ -83,6 +84,7 @@ static int panel_dpi_enable(struct omap_dss_device *dssdev) if (r) return r; + gpiod_set_value_cansleep(ddata->reset_gpio, 0); gpiod_set_value_cansleep(ddata->enable_gpio, 1); if (gpio_is_valid(ddata->backlight_gpio))@@ -211,6 +213,11 @@ static int panel_dpi_probe_of(struct platform_device *pdev) if (IS_ERR(ddata->enable_gpio)) return PTR_ERR(ddata->enable_gpio); + ddata->reset_gpio = devm_gpiod_get_optional(&pdev->dev, + "reset", GPIOD_OUT_HIGH); + if (IS_ERR(ddata->reset_gpio)) + return PTR_ERR(ddata->reset_gpio); + ddata->backlight_gpio = -ENOENT; r = of_get_display_timing(node, "panel-timing", &timing);
This looks a bit odd to me. This only ever sets the reset gpio to 0, on panel enable. If we never toggle the reset, it could be set to 0 at probe time, right? Reset is a bit tricky. I've seen panels where you have to have only a short reset pulse (reset high, wait a short time, reset low). If you leave the reset high, the panel draws extra power. So I think the best we can do in a generic way is just to ensure the reset is not asserted. Tomi
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