>-----Original Message----- >From: Michel Dänzer <michel@xxxxxxxxxxx> >Sent: Friday, December 21, 2018 5:37 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 10:32 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. Yes, it is not a good idea to leave it pinned. Then will need lots of "if (amdgpu_virtual_display)", don't know whether it could be accept? > > >-- >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
