Am Freitag, den 09.08.2019, 14:04 +0200 schrieb Lucas Stach:
This builds on top of the MMU contexts introduced earlier. Instead of having one context per GPU core, each GPU client receives its own context.
On MMUv1 this still means a single shared pagetable set is used by all clients, but on MMUv2 there is now a distinct set of pagetables for each client. As the command fetch is also translated via the MMU on MMUv2 the kernel command ringbuffer is mapped into each of the client pagetables.
As the MMU context switch is a bit of a heavy operation, due to the needed cache and TLB flushing, this patch implements a lazy way of switching the MMU context. The kernel does not have its own MMU context, but reuses the last client context for all of its operations. This has some visible impact, as the GPU can now only be started once a client has submitted some work and we got the client MMU context assigned. Also the MMU context has a different lifetime than the general client context, as the GPU might still execute the kernel command buffer in the context of a client even after the client has completed all GPU work and has been terminated. Only when the GPU is runtime suspended or switches to another clients MMU context is the old context freed up.
Signed-off-by: Lucas Stach l.stach@pengutronix.de
v3: Don't call etnaviv_cmdbuf_suballoc_unmap when mapping failed.
[...]
/* @@ -308,7 +312,8 @@ void etnaviv_sync_point_queue(struct etnaviv_gpu *gpu, unsigned int event) /* Append a command buffer to the ring buffer. */ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
- unsigned int event, struct etnaviv_cmdbuf *cmdbuf)
- struct etnaviv_iommu_context *mmu_context, unsigned int event,
- struct etnaviv_cmdbuf *cmdbuf)
{
struct etnaviv_cmdbuf *buffer = &gpu->buffer; unsigned int waitlink_offset = buffer->user_size - 16;
@@ -317,17 +322,19 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
bool switch_context = gpu->exec_state != exec_state; unsigned int new_flush_seq = READ_ONCE(gpu->mmu_context->flush_seq); bool need_flush = gpu->flush_seq != new_flush_seq;
- bool switch_mmu_context = gpu->mmu_context != mmu_context;
I screwed up this one during the rework to avoid the flush sequence race. I'll squash the following into this commit:
--- a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c +++ b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c @@ -320,9 +320,9 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state, u32 return_target, return_dwords; u32 link_target, link_dwords; bool switch_context = gpu->exec_state != exec_state; - unsigned int new_flush_seq = READ_ONCE(gpu->mmu_context->flush_seq); - bool need_flush = gpu->flush_seq != new_flush_seq; bool switch_mmu_context = gpu->mmu_context != mmu_context; + unsigned int new_flush_seq = READ_ONCE(gpu->mmu_context->flush_seq); + bool need_flush = switch_mmu_context || gpu->flush_seq != new_flush_seq;