Hi, On Thu, Nov 10, 2011 at 5:50 PM, Simon Que <s...@chromium.org> wrote: > If the firmware did not initialize the backlight PWM registers, set up a > default PWM frequency of 200 Hz. This is determined using the following > formula: > > freq = refclk / (128 * pwm_max) > > The PWM register allows the max PWM value to be set. So we want to use > the formula, where freq = 200: > > pwm_max = refclk / (128 * freq) > > This patch will, in the case of missing PWM register initialization > values, look for the reference clock frequency. Based on that, it sets > an appropriate max PWM value for a frequency of 200 Hz. > > If no refclk frequency is found, the max PWM will be zero, which results > in no change to the PWM registers.
I think the general approach of finding a suitable PWM setting is better this way, but you're attacking the problem at the wrong level. There is already a place to hook in this in intel_panel_get_max_backlight(): Do it there in the "XXX add code" case, have the helper update the dev_priv fields to the calculated max and call i915_read_blc_pwm_ctl() again to program said fields. -Olof _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx