On Mon, 15 Apr 2013, Chris Wilson <chris at chris-wilson.co.uk> wrote: > On Fri, Apr 12, 2013 at 03:18:37PM +0300, Jani Nikula wrote: >> Backlight data and registers are fiddled through LVDS/eDP modeset >> enable/disable hooks, backlight sysfs files, asle interrupts, and register >> save/restore. Protect the backlight related registers and driver private >> fields using a spinlock. >> >> The locking in register save/restore covers a little more than is strictly >> necessary, including non-modeset case, for simplicity. >> >> v2: Cover register access, save/restore, i915_read_blc_pwm_ctl() and code >> paths leading there. >> >> Signed-off-by: Jani Nikula <jani.nikula at intel.com> > > Looks reasonable. > > intel_panel_actually_set_backlight() should have a WARN_ON(!spinlocked); > > The irqness of the register writes scares me slightly - since the IRQ in > question is from ACPI and we have a few bug reports along the lines of > "backlight makes the entire system sluggish" i.e. commonly associated > with bad interrupt handling. Whilst you are looking at updating the > backlight programming, can you look at pushing the writes from out > of the interrupt handler? So, add a work to do the register writes, and change the spinlock into a mutex while at it? Should be fairly simple, if you think that's the way to go. BR, Jani.
