Re: [RFC v5 9/9] drm/i915: Backlight control using CRC PMIC based PWM driver

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 12, 2015 at 10:01:33PM +0530, Shobhit Kumar wrote:
> CC: Samuel Ortiz <sameo@linux.intel.com>
> Cc: Linus Walleij <linus.walleij@linaro.org>
> Cc: Alexandre Courbot <gnurou@gmail.com>
> Cc: Thierry Reding <thierry.reding@gmail.com>
> Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dsi.c | 25 +++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_dsi.h |  3 +++
>  2 files changed, 28 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dsi.c b/drivers/gpu/drm/i915/intel_dsi.c
> index 219421c..511446f 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.c
> +++ b/drivers/gpu/drm/i915/intel_dsi.c
> @@ -32,6 +32,7 @@
>  #include <drm/drm_mipi_dsi.h>
>  #include <linux/slab.h>
>  #include <linux/gpio/consumer.h>
> +#include <linux/pwm.h>
>  #include "i915_drv.h"
>  #include "intel_drv.h"
>  #include "intel_dsi.h"
> @@ -402,6 +403,10 @@ static void intel_dsi_enable(struct intel_encoder *encoder)
>  
>  		intel_dsi_port_enable(encoder);
>  	}
> +
> +	/* Enable the backlight with default PWM as programmed by BIOS */
> +	pwm_enable(intel_dsi->pwm);
> +	pwm_config_alternate(intel_dsi->pwm, 0x7F, 100);

I suppose we migth want to wrap these in 'if (intel_dsi->pwm)' checks,
or does the pwm subsystem take care of NULL checks for us?

>  }
>  
>  static void intel_dsi_pre_enable(struct intel_encoder *encoder)
> @@ -467,6 +472,11 @@ static void intel_dsi_pre_disable(struct intel_encoder *encoder)
>  
>  	DRM_DEBUG_KMS("\n");
>  
> +	/* Disable the backlight */
> +	pwm_config_alternate(intel_dsi->pwm, 0x7F, 0);
> +	usleep_range(2000, 3000);
> +	pwm_disable(intel_dsi->pwm);

ditto

> +
>  	if (is_vid_mode(intel_dsi)) {
>  		/* Send Shutdown command to the panel in LP mode */
>  		for_each_dsi_port(port, intel_dsi->ports)
> @@ -971,6 +981,10 @@ static void intel_dsi_encoder_destroy(struct drm_encoder *encoder)
>  	if (intel_dsi->gpio_panel)
>  		gpiod_put(intel_dsi->gpio_panel);
>  
> +	/* dispose of the pwm */
> +	if (intel_dsi->pwm)
> +		pwm_put(intel_dsi->pwm);
> +
>  	intel_encoder_destroy(encoder);
>  }
>  
> @@ -1098,6 +1112,17 @@ void intel_dsi_init(struct drm_device *dev)
>  			DRM_ERROR("Failed to own gpio for panel control\n");
>  			intel_dsi->gpio_panel = NULL;
>  		}
> +
> +		/* Get the PWM chip for backlight control */
> +		intel_dsi->pwm = pwm_get(dev->dev, "pwm_backlight");
> +		if (IS_ERR(intel_dsi->pwm)) {
> +			DRM_ERROR("Faild to own the pwm chip\n");
> +			intel_dsi->pwm = NULL;
> +		} else if (pwm_config_alternate(intel_dsi->pwm, 0x7F, 100) < 0) {
> +			DRM_ERROR("Failed to configure the pwm chip\n");
> +			pwm_put(intel_dsi->pwm);
> +			intel_dsi->pwm = NULL;
> +		}
>  	}
>  
>  	intel_encoder->type = INTEL_OUTPUT_DSI;
> diff --git a/drivers/gpu/drm/i915/intel_dsi.h b/drivers/gpu/drm/i915/intel_dsi.h
> index 8be75a7..d8ec9c1 100644
> --- a/drivers/gpu/drm/i915/intel_dsi.h
> +++ b/drivers/gpu/drm/i915/intel_dsi.h
> @@ -52,6 +52,9 @@ struct intel_dsi {
>  	/* GPIO Desc for CRC based Panel control */
>  	struct gpio_desc *gpio_panel;
>  
> +	/* PWM chip */
> +	struct pwm_device *pwm;
> +
>  	struct intel_connector *attached_connector;
>  
>  	/* bit mask of ports being driven */
> -- 
> 2.1.0
> 
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-- 
Ville Syrjälä
Intel OTC
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