Huang Gao (Gmail) wrote: > Dear all Maemo fans: > > I just noticed that Maemo used a different mechanism in LCD > driver from normal FB drivers. It seemed that Maemo does not use the > automatic DMA refresh in the driver, which is replaced by an ioctl named > OMAPFB_UPDATE_WINDOW, and a method called TEARSYNC. However, I am > confused why it will improve the performance of graphics applications. > Is there anyone that may give me some tips on this topic?
This was done because of relatively high resolution (800x480x16 bits). Automatic DMA would continuously steal a lot of SDRAM cycles and slowed down everything. Perhaps it would also eat more power and prevented system from sleep when the display is on. I wonder if this is still the case for upcoming OMAP3 based device. BTW, there is kernel ioctl to set automatic refresh and the refresh rate can be tweaked in kernel source but the results are suboptimal. Maybe at least for Nokia 770 it would be possible to use tearsync flag for such automatic update and set the update timer to lcd refresh rate or lcd refresh rate/2 to get nice result. N8x0 cannot update whole screen in one lcd refresh cycle anyway so you'll always get tearing on the bottom. Frantisek _______________________________________________ maemo-developers mailing list maemo-developers@maemo.org https://lists.maemo.org/mailman/listinfo/maemo-developers
