On Mon, Apr 15, 2013 at 6:38 PM, Jani Nikula <jani.nikula at intel.com> wrote: > 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. I think I'll go ahead with the spinlock fix here for 3.10 and we can look into offloading this all for 3.11. Also, Chris do you remember one of these reports - I've kinda never noticed that particular kind of suck? -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch
