On 05/10/2020 09:39, Boris Brezillon wrote:
On Mon, 5 Oct 2020 09:34:06 +0100
Steven Price <steven.price@xxxxxxx> wrote:
On 05/10/2020 09:15, Boris Brezillon wrote:
Hi Robin, Neil,
On Wed, 16 Sep 2020 10:26:43 +0200
Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote:
Hi Robin,
On 16/09/2020 01:51, Robin Murphy wrote:
According to a downstream commit I found in the Khadas vendor kernel,
the GPU on G12b is wired up for ACE-lite, so (now that Panfrost knows
how to handle this properly) we should describe it as such. Otherwise
the mismatch leads to all manner of fun with mismatched attributes and
inadvertently snooping stale data from caches, which would account for
at least some of the brokenness observed on this platform.
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
arch/arm64/boot/dts/amlogic/meson-g12b.dtsi | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi
index 9b8548e5f6e5..ee8fcae9f9f0 100644
--- a/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-g12b.dtsi
@@ -135,3 +135,7 @@ map1 {
};
};
};
+
+&mali {
+ dma-coherent;
+};
Thanks a lot for digging, I'll run a test to confirm it fixes the issue !
Sorry for the late reply. I triggered a dEQP run with this patch applied
and I see a bunch of "panfrost ffe40000.gpu: matching BO is not heap type"
errors (see below for a full backtrace). That doesn't seem to happen when
we drop this dma-coherent property.
[ 690.945731] ------------[ cut here ]------------
[ 690.950003] panfrost ffe40000.gpu: matching BO is not heap type (GPU VA = 319a000)
[ 690.950051] WARNING: CPU: 0 PID: 120 at drivers/gpu/drm/panfrost/panfrost_mmu.c:465 panfrost_mmu_irq_handler_thread+0x47c/0x650
[ 690.968854] Modules linked in:
[ 690.971878] CPU: 0 PID: 120 Comm: irq/27-panfrost Tainted: G W 5.9.0-rc5-02434-g7d8109ec5a42 #784
[ 690.981964] Hardware name: Khadas VIM3 (DT)
[ 690.986107] pstate: 60000005 (nZCv daif -PAN -UAO BTYPE=--)
[ 690.991627] pc : panfrost_mmu_irq_handler_thread+0x47c/0x650
[ 690.997232] lr : panfrost_mmu_irq_handler_thread+0x47c/0x650
[ 691.002836] sp : ffff800011bcbcd0
[ 691.006114] x29: ffff800011bcbcf0 x28: ffff0000f3fe3800
[ 691.011375] x27: ffff0000ceaf5350 x26: ffff0000ca5fc500
[ 691.016636] x25: ffff0000f32409c0 x24: 0000000000000001
[ 691.021897] x23: ffff0000f3240880 x22: ffff0000f3e3a800
[ 691.027159] x21: 0000000000000000 x20: 0000000000000000
[ 691.032420] x19: 0000000000010001 x18: 0000000000000020
[ 691.037681] x17: 0000000000000000 x16: 0000000000000000
[ 691.042942] x15: ffff0000f3fe3c70 x14: ffffffffffffffff
[ 691.048204] x13: ffff8000116c2428 x12: ffff8000116c2086
[ 691.053466] x11: ffff800011bcbcd0 x10: ffff800011bcbcd0
[ 691.058727] x9 : 00000000fffffffe x8 : 0000000000000000
[ 691.063988] x7 : 7420706165682074 x6 : ffff8000116c1816
[ 691.069249] x5 : 0000000000000000 x4 : 0000000000000000
[ 691.074510] x3 : 00000000ffffffff x2 : ffff8000e348c000
[ 691.079771] x1 : f1b91ff9af2df000 x0 : 0000000000000000
[ 691.085033] Call trace:
[ 691.087452] panfrost_mmu_irq_handler_thread+0x47c/0x650
[ 691.092712] irq_thread_fn+0x2c/0xa0
[ 691.096246] irq_thread+0x184/0x208
[ 691.099699] kthread+0x140/0x160
[ 691.102890] ret_from_fork+0x10/0x34
[ 691.106424] ---[ end trace b5dd8c2dfada8236 ]---
It's quite possible this is caused by the GPU seeing a stale page table
entry, so perhaps coherency isn't working as well as it should...
Do you get an "Unhandled Page fault" message after this?
Yep (see below).
--->8---
[...]
[ 689.805864] panfrost ffe40000.gpu: Unhandled Page fault in AS0 at VA 0x0000000003146080
[ 689.805864] Reason: TODO
[ 689.805864] raw fault status: 0x10003C3
[ 689.805864] decoded fault status: SLAVE FAULT
[ 689.805864] exception type 0xC3: TRANSLATION_FAULT_LEVEL3
[ 689.805864] access type 0x3: WRITE
[ 689.805864] source id 0x100
[ 690.170419] panfrost ffe40000.gpu: gpu sched timeout, js=1, config=0x7300, status=0x8, head=0x3101100, tail=0x3101100, sched_job=000000004b442768
[ 690.770373] panfrost ffe40000.gpu: error powering up gpu shader
[ 690.945123] panfrost ffe40000.gpu: error powering up gpu shader
[ 690.945731] ------------[ cut here ]------------
That's a write fault from level 3 of the page table triggered by shader
core 0 in a fragment job. So could be writing out the frame buffer.
It would be interesting to see if a patch like below would work round
it:
----8<----
diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c
index e8f7b11352d2..5144860afdea 100644
--- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
+++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
@@ -460,9 +460,12 @@ static int panfrost_mmu_map_fault_addr(struct panfrost_device *pfdev, int as,
bo = bomapping->obj;
if (!bo->is_heap) {
- dev_WARN(pfdev->dev, "matching BO is not heap type (GPU VA = %llx)",
+ dev_err(pfdev->dev, "matching BO is not heap type (GPU VA = %llx)",
bomapping->mmnode.start << PAGE_SHIFT);
- ret = -EINVAL;
+ /* Force a flush of the MMU to restart the transaction */
+ mmu_hw_do_operation(pfdev, bomapping->mmu, addr, 0,
+ AS_COMMAND_FLUSH_MEM);
+ ret = 0;
goto err_bo;
}
WARN_ON(bomapping->mmu->as != as);
---8<---
That's obviously not the correct solution (the fault shouldn't occur),
but if flushing the GPU's caches and retrying works then we know it's
a coherency issue. You can also try backing off from the big hammer of
AS_COMMAND_FLUSH_MEM and trying AS_COMMAND_FLUSH_PT or
AS_COMMAND_UNLOCK.
Steve
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