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

[Shobhit Kumar <shobhit.kumar@linux.intel.com>]

On 03/13/2015 08:00 PM, Ville Syrjälä wrote:
> 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?

PWM subsystem does make the checks. Actually this patch is kind of
prelim patch and I have to still hook up pwm usage in our back-light
infra in intel_panel.c. I have a working patch for that though not
posted yet. Will take care in that final patch for enabling this.

Regards
Shobhit

> 
>>  }
>>  
>>  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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> 
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