Dmitry Baryshkov <[email protected]> 于2026年1月26日周一 18:49写道： > > On 26/01/2026 12:29, Jun Nie wrote: > > Dmitry Baryshkov <[email protected]> 于2026年1月26日周一 18:13写道： > >> > >> On 26/01/2026 12:06, Jun Nie wrote: > >>> Dmitry Baryshkov <[email protected]> 于2026年1月22日周四 > >>> 18:22写道： > >>>> > >>>> On Thu, Jan 22, 2026 at 02:03:25PM +0800, Jun Nie wrote: > >>>>> Dmitry Baryshkov <[email protected]> 于2026年1月21日周三 > >>>>> 17:30写道： > >>>>>> > >>>>>> On Wed, Jan 21, 2026 at 04:01:51PM +0800, Jun Nie wrote: > >>>>>>> Currently, plane splitting and SSPP allocation occur during the plane > >>>>>>> check phase. Defer these operations until dpu_assign_plane_resources() > >>>>>>> is called from the CRTC side to ensure the topology information from > >>>>>>> the CRTC check is available. > >>>>>> > >>>>>> Why is it important? What is broken otherwise? > >>>>> > >>>>> I see. Thanks! Will add below lines in next version. > >>>>> > >>>>> By default, the plane check occurs before the CRTC check. > >>>>> Without topology information from the CRTC, plane splitting > >>>>> cannot be properly executed. Consequently, the SSPP > >>>>> engine starts without a valid memory address, which triggers > >>>>> an IOMMU warning. > >>>> > >>>> What is plane splitting? Write commit message for somebody who doesn't > >>>> exactly know what is going on. > >>> > >>> Thanks for the suggestion! Any more revise is needed? > >> > >> Sadly enough the text below is not a significant improvement. > >> > >>> > >>> Currently, splitting plane into SSPP rectangles the allocation occur > >>> during the plane check phase, so that a plane can be supported by > >>> multiple hardware pipe. > >> > >> What does this mean? Without virtual planes in place, there are no > >> multiple hardware pipes. > >> > >>> While pipe topology is decided in CRTC check. > >> > >> ?? What does it mean here? > >> > >>> By default, the plane check occurs before the CRTC check in DRM > >>> framework. Without topology information from the CRTC, plane splitting > >>> cannot be properly executed. > >> > >> What does 'properly' mean here? How is it executed? What happens? > >> > >>> Consequently, the SSPP engine starts > >>> without a valid memory address, which triggers IOMMU warning. > >> > >> IOMMU faults. There are no "warnings". > >> > >>> > >>> Defer above plane operations until dpu_assign_plane_resources() > >>> is called from the CRTC side to ensure the topology information from > >>> the CRTC check is available. > >> > >> > > Thanks for the patience! > > > > > > Currently, splitting plane into SSPP rectangles and allocation occur > > during the plane check phase. When virtual plane is enabled to support > > quad-pipe topology later, 2 SSPPs with 4 rect will be needed, so that > > a plane can be supported by 4 hardware pipes. And pipe number is > > number of pipes > > > decided in CRTC check per interface number, resolution and hardware > > feature. > > Okay, but IOMMU errors were reported with virtual planes being disabled. > So how is it relevant?
After revise of splitting plane into pipes, the number of pipes will be decided by CRTC check for both virtual plane and non-virtual plane case to unify the plane handling, instead of assumption of 2 pipes at most. > > > > > By default, the plane check occurs before the CRTC check in DRM > > framework. Without topology information from the CRTC, plane splitting > > WHat is plane splitting? How about: s/plane splitting/splitting plane into pipes ? > > > will be skipped for the first time as pipe number is 0. Consequently, > > the SSPP engine starts without a valid memory address, which triggers > > IOMMU fault. > > > > Defer above plane related operations until dpu_assign_plane_resources() > > is called from the CRTC side to ensure the topology information from > > the CRTC check is available. > > > > Regards, > > Jun > >> > >> -- > >> With best wishes > >> Dmitry > > > -- > With best wishes > Dmitry
