Hi Am 11.06.19 um 17:33 schrieb Daniel Vetter: > On Tue, Jun 11, 2019 at 2:32 PM Thomas Zimmermann <tzimmermann@xxxxxxx> wrote: >> >> Hi >> >> Am 05.06.19 um 11:58 schrieb Gerd Hoffmann: >>> On Tue, Jun 04, 2019 at 05:41:59PM +0200, Thomas Zimmermann wrote: >>>> The cursor handling in mgag200 is complicated to understand. It touches a >>>> number of different BOs, but doesn't really use all of them. >>>> >>>> Rewriting the cursor update reduces the amount of cursor state. There are >>>> two BOs for double-buffered HW updates. The source BO updates the one that >>>> is currently not displayed and then switches buffers. Explicit BO locking >>>> has been removed from the code. BOs are simply pinned and unpinned in video >>>> RAM. >>> >>> Cursors are not that big after all, so maybe pin the two BOs for >>> double-buffering permanently in vram to simplify things further? >>> >>> Also factoring out the code which updates the two BOs to a separate >>> function should help making the code more readable. >> >> The cursor handling in the ast driver is similar, but uses one single BO >> to hold both cursor buffers. I'm thinking about how to turn both >> implementations into a generic helper for legacy cursors (i.e., low >> number of colors or palette). This would also be helpful for my work on >> fbdev porting. >> >> One idea is to adapt deferred I/O. DRM would expose an ARGB shadow >> buffer to userspace and let the mmap implementation update the HW >> buffers (including dithering, palette setup, etc.). > > No mmap games needed with kms, we expect userspace to give us an ioctl > call in all cases. fbdev is the legacy horrors that works differently. Thanks for clarifying this. Conversion should be much easier this way. I saw the dirty callback and the DIRTYFB ioctl, but I don't saw anything in Weston that calls it. So I assumed that it's obsolete or optional. Best regards Thomas > So for cursors, assuming you have universal cursors, you just need to > update the shadowed copy in the prepare_fb plane hook. For > non-universal plane drivers you need to do that somewhere in your > set/move_cursor hooks (I think both of them). Aside: For non-cursors > there's also the dirtyfb ioctl, which serves the same purpose. > > Cheers, Daniel > >> >> Best regards >> Thomas >> >>> But even as-is the patch is a step into the right direction. >>> >>> Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx> >>> >>> cheers, >>> Gerd >>> >> >> -- >> Thomas Zimmermann >> Graphics Driver Developer >> SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany >> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah >> HRB 21284 (AG Nürnberg) >> > > -- Thomas Zimmermann Graphics Driver Developer SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany GF: Felix Imendörffer, Mary Higgins, Sri Rasiah HRB 21284 (AG Nürnberg)
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