On 2018-12-21 10:32 a.m., Deng, Emily wrote: >> -----Original Message----- >> From: Michel Dänzer <michel@xxxxxxxxxxx> >> Sent: Friday, December 21, 2018 5:28 PM >> To: Deng, Emily <Emily.Deng@xxxxxxx> >> Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx >> Subject: Re: [PATCH] drm/amdgpu/virtual_dce: Need to pin the fb's bo >> >> On 2018-12-21 10:17 a.m., Deng, Emily wrote: >>>> From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of >>>> Deng, Emily >>>>> From: Michel Dänzer <michel@xxxxxxxxxxx> On 2018-12-21 9:45 a.m., >>>>> Deng, Emily wrote: >>>>>>> From: Michel Dänzer <michel@xxxxxxxxxxx> On 2018-12-21 8:26 a.m., >>>>>>> Emily Deng wrote: >>>>>>>> When the bo is used to set mode, the bo need to be pinned. >>>>>>> >>>>>>> On second thought, why does the BO need to be pinned? When using >>>>>>> the display hardware, the BO needs to be pinned to prevent it from >>>>>>> being moved while the hardware is scanning out from it, but that >>>>>>> shouldn't be >>>>> necessary here. >>>>>> The pin here is used for scan out the buffer by remote display app. >>>>> >>>>> I still don't understand why pinning is needed. What mechanism does >>>>> the remote display app use to access the BO contents? >>>> Sorry, I am not familiar with the remote display app. Maybe it will >>>> use drm ioctl function to get the current crtc's fb's information, >>>> and get the content in the fb's buffer object by mmap or translate >>>> the bo to an OpenGL texture for next rendering. Maybe don't need to >>>> pin the bo here, as the use has no different with other normal bos. >>>> So please ignore the patch, and will send another patch to remove the unpin >> the fb's bo code. >>> It seems to be hard to remove all the pin for virtual_dce, as it uses some >> common code in amdgpu_display.c. >> >> Because of amdgpu_display_unpin_work_func? That might be as simple as >> replacing >> >> schedule_work(&works->unpin_work); >> >> with >> >> kfree(works->shared); >> kfree(works); >> >> in dce_virtual_pageflip. > But the amdgpu_display_crtc_page_flip_target will pin the new_bo, then > we don't need to unpin it? Ah, right, but then dce_virtual_pageflip could just unpin it? Not ideal, but better than leaving it pinned unnecessarily. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
