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

[Daniel Vetter]

On Fri, Mar 13, 2015 at 04:30:43PM +0200, Ville Syrjälä wrote:
> On Thu, Mar 12, 2015 at 10:01:33PM +0530, Shobhit Kumar wrote:
> > CC: Samuel Ortiz <sameo at linux.intel.com>
> > Cc: Linus Walleij <linus.walleij at linaro.org>
> > Cc: Alexandre Courbot <gnurou at gmail.com>
> > Cc: Thierry Reding <thierry.reding at gmail.com>
> > Signed-off-by: Shobhit Kumar <shobhit.kumar at 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;

If the i915.ko driver loads before the mfd.ko driver we need to do a
deferred probe here I think. Just failing isn't robust.

This also means that if people don't configure their kernel properly then
we'll fall over here, but meh.
-Daniel

> > +		} 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
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch