Re: [PATCH v7 4/4] drm/mediatek: set dpi pin mode to gpio low to avoid leakage current

Hi, Jitao:

On Tue, 2020-02-25 at 14:46 +0800, Jitao Shi wrote:

Config dpi pins mode to output and pull low when dpi is disabled. Aovid leakage current from some dpi pins (Hsync Vsync DE ... ).

Signed-off-by: Jitao Shi jitao.shi@mediatek.com

drivers/gpu/drm/mediatek/mtk_dpi.c | 33 ++++++++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c index c3e631b93c2e..ca570040ffdf 100644 --- a/drivers/gpu/drm/mediatek/mtk_dpi.c +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c @@ -10,7 +10,9 @@ #include <linux/kernel.h> #include <linux/of.h> #include <linux/of_device.h> +#include <linux/of_gpio.h> #include <linux/of_graph.h> +#include <linux/pinctrl/consumer.h> #include <linux/platform_device.h> #include <linux/types.h>

@@ -74,6 +76,9 @@ struct mtk_dpi { enum mtk_dpi_out_yc_map yc_map; enum mtk_dpi_out_bit_num bit_num; enum mtk_dpi_out_channel_swap channel_swap;

• struct pinctrl *pinctrl;
• struct pinctrl_state *pins_gpio;
• struct pinctrl_state *pins_dpi; int refcount; u32 pclk_sample;

}; @@ -387,6 +392,9 @@ static void mtk_dpi_power_off(struct mtk_dpi *dpi) if (--dpi->refcount != 0) return;

• if (dpi->pinctrl && dpi->pins_gpio)

• pinctrl_select_state(dpi->pinctrl, dpi->pins_gpio);
  

• mtk_dpi_disable(dpi); clk_disable_unprepare(dpi->pixel_clk); clk_disable_unprepare(dpi->engine_clk);

@@ -411,6 +419,9 @@ static int mtk_dpi_power_on(struct mtk_dpi *dpi) goto err_pixel; }

• if (dpi->pinctrl && dpi->pins_dpi)

• pinctrl_select_state(dpi->pinctrl, dpi->pins_dpi);
  

• mtk_dpi_enable(dpi); return 0;

@@ -716,8 +727,26 @@ static int mtk_dpi_probe(struct platform_device *pdev)

dpi->dev = dev; dpi->conf = (struct mtk_dpi_conf *)of_device_get_match_data(dev);

• dpi->pclk_sample = of_property_read_u32_index(dev->of_node,

• 				      "pclk-sample");
  

• of_property_read_u32_index(dev->of_node, "pclk-sample", 1,

• 		   &dpi->pclk_sample);
  

Why this exists in this patch?

• dpi->pinctrl = devm_pinctrl_get(&pdev->dev);
• if (IS_ERR(dpi->pinctrl))

• dev_dbg(&pdev->dev, "Cannot find pinctrl!\n");
  

I think you should set dpi->pinctrl to NULL when error, and check dpi->pinctrl before you use it, such as pinctrl_lookup_state().

Regards, CK

• dpi->pins_gpio = pinctrl_lookup_state(dpi->pinctrl, "gpiomode");

• if (IS_ERR(dpi->pins_gpio)) {

• dpi->pins_gpio = NULL;
  

• dev_dbg(&pdev->dev, "Cannot find pinctrl gpiomode!\n");
  

• }

• if (dpi->pinctrl && dpi->pins_gpio)

• pinctrl_select_state(dpi->pinctrl, dpi->pins_gpio);
  

• dpi->pins_dpi = pinctrl_lookup_state(dpi->pinctrl, "dpimode");

• if (IS_ERR(dpi->pins_dpi)) {

• dpi->pins_dpi = NULL;
  

• dev_dbg(&pdev->dev, "Cannot find pinctrl dpimode!\n");
  

• }

  mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); dpi->regs = devm_ioremap_resource(dev, mem);