On 30/09/2024 17:05, Hugo Villeneuve wrote:

On Mon, 30 Sep 2024 16:38:14 +0200 Neil Armstrong neil.armstrong@linaro.org wrote:

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Hi,

On 27/09/2024 15:53, Hugo Villeneuve wrote:

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From: Hugo Villeneuve hvilleneuve@dimonoff.com

In jadard_prepare() a reset pulse is generated with the following statements (delays ommited for clarity):

  gpiod_set_value(jadard->reset, 1); --> Deassert reset
  gpiod_set_value(jadard->reset, 0); --> Assert reset for 10ms
  gpiod_set_value(jadard->reset, 1); --> Deassert reset

However, specifying second argument of "0" to gpiod_set_value() means to deassert the GPIO, and "1" means to assert it. If the reset signal is defined as GPIO_ACTIVE_LOW in the DTS, the above statements will incorrectly generate the reset pulse (inverted) and leave it asserted (LOW) at the end of jadard_prepare().

Did you check the polarity in DTS of _all_ users of this driver ?

Hi Neil, I confirmed that no in-tree DTS is referencing this driver. I did a search of all the compatible strings defined in the "jadard,jd9365da-h3.yaml" file. I also did the same on Debian code search.

OK then: Reviewed-by: Neil Armstrong neil.armstrong@linaro.org

Hugo.

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Neil

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Fix reset behavior by inverting gpiod_set_value() second argument in jadard_prepare(). Also modify second argument to devm_gpiod_get() in jadard_dsi_probe() to assert the reset when probing.

Do not modify it in jadard_unprepare() as it is already properly asserted with "1", which seems to be the intended behavior.

Fixes: 6b818c533dd8 ("drm: panel: Add Jadard JD9365DA-H3 DSI panel") Cc: stable@vger.kernel.org Signed-off-by: Hugo Villeneuve hvilleneuve@dimonoff.com

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drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c index 44897e5218a69..6fec99cf4d935 100644 --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c @@ -110,13 +110,13 @@ static int jadard_prepare(struct drm_panel *panel) if (jadard->desc->lp11_to_reset_delay_ms) msleep(jadard->desc->lp11_to_reset_delay_ms);

• gpiod_set_value(jadard->reset, 1);

• gpiod_set_value(jadard->reset, 0); msleep(5);

• gpiod_set_value(jadard->reset, 0);

• gpiod_set_value(jadard->reset, 1); msleep(10);

• gpiod_set_value(jadard->reset, 1);

• gpiod_set_value(jadard->reset, 0); msleep(130); ret = jadard->desc->init(jadard);

@@ -1131,7 +1131,7 @@ static int jadard_dsi_probe(struct mipi_dsi_device *dsi) dsi->format = desc->format; dsi->lanes = desc->lanes;

• jadard->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);

• jadard->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(jadard->reset)) { DRM_DEV_ERROR(&dsi->dev, "failed to get our reset GPIO\n"); return PTR_ERR(jadard->reset);

base-commit: 18ba6034468e7949a9e2c2cf28e2e123b4fe7a50