From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrzej Hajda <a.hajda@samsung.com>
Subject: Re: [PATCH v6 05/14] drm/exynos: dsi: add TE interrupt handler to
 support LCD I80 interface
Date: Mon, 21 Jul 2014 16:01:03 +0200
Message-ID: <53CD1D1F.1050109@samsung.com>
References: <1405587689-1466-1-git-send-email-yj44.cho@samsung.com>
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To: YoungJun Cho <yj44.cho@samsung.com>, airlied@linux.ie, dri-devel@lists.freedesktop.org
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, linux-samsung-soc@vger.kernel.org, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, sw0312.kim@samsung.com, kyungmin.park@samsung.com, robh+dt@kernel.org, galak@codeaurora.org, kgene.kim@samsung.com
List-Id: devicetree@vger.kernel.org

On 07/17/2014 11:01 AM, YoungJun Cho wrote:
> To support LCD I80 interface, the DSI host should register
> TE interrupt handler from the TE GPIO of attached panel.
> So the panel generates a tearing effect synchronization signal
> then the DSI host calls the CRTC device manager to trigger
> to transfer video image.
> 

This whole patch seems to be a hack.

I think it is not a good idea to parse property of one device by another
device's driver.

Especially here TE GPIO belongs to the panel. The panel driver should
know how to configure it and how to use it or not. The panel driver will
generate TE signal based on this GPIO, DSI/BTA mechanism or any other
mechanism provided by the panel.
TE signal should be delivered to the display controller. The only role
of DSIM here is that it is between the panel and the display controller
so it should be used to route this signal to DC.

According to specs TE signal should/can be generated by DBI and DSI
command mode panels, so its handling should be more generic, not Exynos
specific.

Regards
Andrzej

> Signed-off-by: YoungJun Cho <yj44.cho@samsung.com>
> Acked-by: Inki Dae <inki.dae@samsung.com>
> Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c | 95 ++++++++++++++++++++++++++++++++-
>  1 file changed, 93 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index 58bfb2a..4997bfe 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -16,7 +16,9 @@
>  #include <drm/drm_panel.h>
>  
>  #include <linux/clk.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/irq.h>
> +#include <linux/of_gpio.h>
>  #include <linux/phy/phy.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/component.h>
> @@ -24,6 +26,7 @@
>  #include <video/mipi_display.h>
>  #include <video/videomode.h>
>  
> +#include "exynos_drm_crtc.h"
>  #include "exynos_drm_drv.h"
>  
>  /* returns true iff both arguments logically differs */
> @@ -247,6 +250,7 @@ struct exynos_dsi {
>  	struct clk *bus_clk;
>  	struct regulator_bulk_data supplies[2];
>  	int irq;
> +	int te_gpio;
>  
>  	u32 pll_clk_rate;
>  	u32 burst_clk_rate;
> @@ -954,17 +958,89 @@ static irqreturn_t exynos_dsi_irq(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> +static irqreturn_t exynos_dsi_te_irq_handler(int irq, void *dev_id)
> +{
> +	struct exynos_dsi *dsi = (struct exynos_dsi *)dev_id;
> +	struct drm_encoder *encoder = dsi->encoder;
> +
> +	if (dsi->state & DSIM_STATE_ENABLED)
> +		exynos_drm_crtc_te_handler(encoder->crtc);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void exynos_dsi_enable_irq(struct exynos_dsi *dsi)
> +{
> +	enable_irq(dsi->irq);
> +
> +	if (gpio_is_valid(dsi->te_gpio))
> +		enable_irq(gpio_to_irq(dsi->te_gpio));
> +}
> +
> +static void exynos_dsi_disable_irq(struct exynos_dsi *dsi)
> +{
> +	if (gpio_is_valid(dsi->te_gpio))
> +		disable_irq(gpio_to_irq(dsi->te_gpio));
> +
> +	disable_irq(dsi->irq);
> +}
> +
>  static int exynos_dsi_init(struct exynos_dsi *dsi)
>  {
>  	exynos_dsi_enable_clock(dsi);
>  	exynos_dsi_reset(dsi);
> -	enable_irq(dsi->irq);
> +	exynos_dsi_enable_irq(dsi);
>  	exynos_dsi_wait_for_reset(dsi);
>  	exynos_dsi_init_link(dsi);
>  
>  	return 0;
>  }
>  
> +static int exynos_dsi_register_te_irq(struct exynos_dsi *dsi)
> +{
> +	int ret;
> +
> +	dsi->te_gpio = of_get_named_gpio(dsi->panel_node, "te-gpios", 0);
> +	if (!gpio_is_valid(dsi->te_gpio)) {
> +		dev_err(dsi->dev, "no te-gpios specified\n");
> +		ret = dsi->te_gpio;
> +		goto out;
> +	}
> +
> +	ret = gpio_request_one(dsi->te_gpio, GPIOF_IN, "te_gpio");
> +	if (ret) {
> +		dev_err(dsi->dev, "gpio request failed with %d\n", ret);
> +		goto out;
> +	}
> +
> +	/*
> +	 * This TE GPIO IRQ should not be set to IRQ_NOAUTOEN, because panel
> +	 * calls drm_panel_init() first then calls mipi_dsi_attach() in probe().
> +	 * It means that te_gpio is invalid when exynos_dsi_enable_irq() is
> +	 * called by drm_panel_init() before panel is attached.
> +	 */
> +	ret = request_threaded_irq(gpio_to_irq(dsi->te_gpio),
> +					exynos_dsi_te_irq_handler, NULL,
> +					IRQF_TRIGGER_RISING, "TE", dsi);
> +	if (ret) {
> +		dev_err(dsi->dev, "request interrupt failed with %d\n", ret);
> +		gpio_free(dsi->te_gpio);
> +		goto out;
> +	}
> +
> +out:
> +	return ret;
> +}
> +
> +static void exynos_dsi_unregister_te_irq(struct exynos_dsi *dsi)
> +{
> +	if (gpio_is_valid(dsi->te_gpio)) {
> +		free_irq(gpio_to_irq(dsi->te_gpio), dsi);
> +		gpio_free(dsi->te_gpio);
> +		dsi->te_gpio = -ENOENT;
> +	}
> +}
> +
>  static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>  				  struct mipi_dsi_device *device)
>  {
> @@ -978,6 +1054,16 @@ static int exynos_dsi_host_attach(struct mipi_dsi_host *host,
>  	if (dsi->connector.dev)
>  		drm_helper_hpd_irq_event(dsi->connector.dev);
>  
> +	/*
> +	 * If attached panel device is for command mode one, dsi should
> +	 * register TE interrupt handler.
> +	 */
> +	if (!(dsi->mode_flags & MIPI_DSI_MODE_VIDEO)) {
> +		int ret = exynos_dsi_register_te_irq(dsi);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	return 0;
>  }
>  
> @@ -986,6 +1072,8 @@ static int exynos_dsi_host_detach(struct mipi_dsi_host *host,
>  {
>  	struct exynos_dsi *dsi = host_to_dsi(host);
>  
> +	exynos_dsi_unregister_te_irq(dsi);
> +
>  	dsi->panel_node = NULL;
>  
>  	if (dsi->connector.dev)
> @@ -1099,7 +1187,7 @@ static void exynos_dsi_poweroff(struct exynos_dsi *dsi)
>  
>  		exynos_dsi_disable_clock(dsi);
>  
> -		disable_irq(dsi->irq);
> +		exynos_dsi_disable_irq(dsi);
>  	}
>  
>  	dsi->state &= ~DSIM_STATE_CMD_LPM;
> @@ -1445,6 +1533,9 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>  		goto err_del_component;
>  	}
>  
> +	/* To be checked as invalid one */
> +	dsi->te_gpio = -ENOENT;
> +
>  	init_completion(&dsi->completed);
>  	spin_lock_init(&dsi->transfer_lock);
>  	INIT_LIST_HEAD(&dsi->transfer_list);
>