[PATCH v4] drm/amdgpu: Ensure the DMA engine is deactivated during set ups
Lang Yu
Lang.Yu at amd.com
Thu Apr 28 10:27:35 UTC 2022
On 04/28/ , ricetons at gmail.com wrote:
> From: Haohui Mai <ricetons at gmail.com>
>
> The patch fully deactivates the DMA engine before setting up the ring
> buffer to avoid potential data races and crashes.
>
> The v4 patch addresses the comments from Lang Yu <Lang.Yu at amd.com>.
>
> Signed-off-by: Haohui Mai <ricetons at gmail.com>
> ---
> drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c | 113 ++++++++++++++-----------
> 1 file changed, 62 insertions(+), 51 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c b/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c
> index 013d2dec81d0..b000117b77d0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c
> +++ b/drivers/gpu/drm/amd/amdgpu/sdma_v5_2.c
> @@ -459,7 +459,6 @@ static void sdma_v5_2_ring_emit_fence(struct amdgpu_ring *ring, u64 addr, u64 se
> }
> }
>
> -
> /**
> * sdma_v5_2_gfx_stop - stop the gfx async dma engines
> *
> @@ -505,17 +504,21 @@ static void sdma_v5_2_rlc_stop(struct amdgpu_device *adev)
> }
>
> /**
> - * sdma_v5_2_ctx_switch_enable - stop the async dma engines context switch
> + * sdma_v5_2_ctx_switch_enable_for_instance - start the async dma engines
> + * context switch for an instance
> *
> * @adev: amdgpu_device pointer
> - * @enable: enable/disable the DMA MEs context switch.
> + * @instance_idx: the index of the SDMA instance
> *
> - * Halt or unhalt the async dma engines context switch.
> + * Unhalt the async dma engines context switch.
> */
> -static void sdma_v5_2_ctx_switch_enable(struct amdgpu_device *adev, bool enable)
> +static void sdma_v5_2_ctx_switch_enable_for_instance(struct amdgpu_device *adev, int instance_idx)
> {
> u32 f32_cntl, phase_quantum = 0;
> - int i;
> +
> + if (WARN_ON(instance_idx >= adev->sdma.num_instances)) {
> + return;
> + }
>
> if (amdgpu_sdma_phase_quantum) {
> unsigned value = amdgpu_sdma_phase_quantum;
> @@ -539,61 +542,71 @@ static void sdma_v5_2_ctx_switch_enable(struct amdgpu_device *adev, bool enable)
> phase_quantum =
> value << SDMA0_PHASE0_QUANTUM__VALUE__SHIFT |
> unit << SDMA0_PHASE0_QUANTUM__UNIT__SHIFT;
> - }
> -
> - for (i = 0; i < adev->sdma.num_instances; i++) {
> - if (enable && amdgpu_sdma_phase_quantum) {
> - WREG32_SOC15_IP(GC, sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_PHASE0_QUANTUM),
> - phase_quantum);
> - WREG32_SOC15_IP(GC, sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_PHASE1_QUANTUM),
> - phase_quantum);
> - WREG32_SOC15_IP(GC, sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_PHASE2_QUANTUM),
> - phase_quantum);
> - }
>
> - if (!amdgpu_sriov_vf(adev)) {
> - f32_cntl = RREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_CNTL));
> - f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_CNTL,
> - AUTO_CTXSW_ENABLE, enable ? 1 : 0);
> - WREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_CNTL), f32_cntl);
> - }
> + WREG32_SOC15_IP(GC,
> + sdma_v5_2_get_reg_offset(adev, instance_idx, mmSDMA0_PHASE0_QUANTUM),
> + phase_quantum);
> + WREG32_SOC15_IP(GC,
> + sdma_v5_2_get_reg_offset(adev, instance_idx, mmSDMA0_PHASE1_QUANTUM),
> + phase_quantum);
> + WREG32_SOC15_IP(GC,
> + sdma_v5_2_get_reg_offset(adev, instance_idx, mmSDMA0_PHASE2_QUANTUM),
> + phase_quantum);
> }
>
> + if (!amdgpu_sriov_vf(adev)) {
> + f32_cntl = RREG32(sdma_v5_2_get_reg_offset(adev, instance_idx, mmSDMA0_CNTL));
> + f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_CNTL,
> + AUTO_CTXSW_ENABLE, 1);
> + WREG32(sdma_v5_2_get_reg_offset(adev, instance_idx, mmSDMA0_CNTL), f32_cntl);
> + }
> }
>
> /**
> - * sdma_v5_2_enable - stop the async dma engines
> + * sdma_v5_2_ctx_switch_disable_all - stop the async dma engines context switch
> *
> * @adev: amdgpu_device pointer
> - * @enable: enable/disable the DMA MEs.
> *
> - * Halt or unhalt the async dma engines.
> + * Halt the async dma engines context switch.
> */
> -static void sdma_v5_2_enable(struct amdgpu_device *adev, bool enable)
> +static void sdma_v5_2_ctx_switch_disable_all(struct amdgpu_device *adev)
> {
> u32 f32_cntl;
> int i;
>
> - if (!enable) {
> - sdma_v5_2_gfx_stop(adev);
> - sdma_v5_2_rlc_stop(adev);
> - }
> + if (amdgpu_sriov_vf(adev))
> + return;
>
> - if (!amdgpu_sriov_vf(adev)) {
> - for (i = 0; i < adev->sdma.num_instances; i++) {
> - f32_cntl = RREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_F32_CNTL));
> - f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_F32_CNTL, HALT, enable ? 0 : 1);
> - WREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_F32_CNTL), f32_cntl);
> - }
> + for (i = 0; i < adev->sdma.num_instances; i++) {
> + f32_cntl = RREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_CNTL));
> + f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_CNTL,
> + AUTO_CTXSW_ENABLE, 0);
> + WREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_CNTL), f32_cntl);
> }
> }
>
> +/**
> + * sdma_v5_2_halt - stop the async dma engines
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * Halt the async dma engines.
> + */
> +static void sdma_v5_2_halt(struct amdgpu_device *adev)
> +{
> + sdma_v5_2_gfx_stop(adev);
> + sdma_v5_2_rlc_stop(adev);
> +}
> +
> /**
> * sdma_v5_2_gfx_resume - setup and start the async dma engines
> *
> * @adev: amdgpu_device pointer
> *
> * Set up the gfx DMA ring buffers and enable them.
> + * It assumes that the dma engine is stopped for each instance.
> + * The function enables the engine and preemptions sequentially for each instance.
> + *
> * Returns 0 for success, error for failure.
> */
> static int sdma_v5_2_gfx_resume(struct amdgpu_device *adev)
> @@ -737,10 +750,7 @@ static int sdma_v5_2_gfx_resume(struct amdgpu_device *adev)
>
> ring->sched.ready = true;
>
> - if (amdgpu_sriov_vf(adev)) { /* bare-metal sequence doesn't need below to lines */
> - sdma_v5_2_ctx_switch_enable(adev, true);
> - sdma_v5_2_enable(adev, true);
> - }
> + sdma_v5_2_ctx_switch_enable_for_instance(adev, i);
>
> r = amdgpu_ring_test_ring(ring);
> if (r) {
> @@ -784,7 +794,7 @@ static int sdma_v5_2_load_microcode(struct amdgpu_device *adev)
> int i, j;
>
> /* halt the MEs */
> - sdma_v5_2_enable(adev, false);
> + sdma_v5_2_halt(adev);
>
> for (i = 0; i < adev->sdma.num_instances; i++) {
> if (!adev->sdma.instance[i].fw)
> @@ -856,8 +866,8 @@ static int sdma_v5_2_start(struct amdgpu_device *adev)
> int r = 0;
>
> if (amdgpu_sriov_vf(adev)) {
> - sdma_v5_2_ctx_switch_enable(adev, false);
> - sdma_v5_2_enable(adev, false);
> + sdma_v5_2_ctx_switch_disable_all(adev);
> + sdma_v5_2_halt(adev);
>
> /* set RB registers */
> r = sdma_v5_2_gfx_resume(adev);
> @@ -865,6 +875,9 @@ static int sdma_v5_2_start(struct amdgpu_device *adev)
> }
>
> if (adev->firmware.load_type == AMDGPU_FW_LOAD_DIRECT) {
> + sdma_v5_2_ctx_switch_disable_all(adev);
> + sdma_v5_2_halt(adev);
You don't need call these functions here.
In original code, you can see sdma_v5_2_load_microcode() calls
sdma_v5_2_enable(adev, false) to halt the engine before load ucode.
What I mean is sdma_v5_2_halt(adev) should have no functional change with
original sdma_v5_2_enable(adev, false), like this,
static void sdma_v5_2_halt(struct amdgpu_device *adev) {
u32 f32_cntl;
int i;
sdma_v5_2_gfx_stop(adev);
sdma_v5_2_rlc_stop(adev);
if (!amdgpu_sriov_vf(adev)) {
for (i = 0; i < adev->sdma.num_instances; i++) {
f32_cntl = RREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_F32_CNTL));
f32_cntl = REG_SET_FIELD(f32_cntl, SDMA0_F32_CNTL, HALT, 1);
WREG32(sdma_v5_2_get_reg_offset(adev, i, mmSDMA0_F32_CNTL), f32_cntl);
}
}
}
But you remove the codes to set the HLAT bit of register mmSDMA0_F32_CNTL.
Regards,
Lang
> r = sdma_v5_2_load_microcode(adev);
> if (r)
> return r;
> @@ -881,12 +894,10 @@ static int sdma_v5_2_start(struct amdgpu_device *adev)
> amdgpu_gfx_off_ctrl(adev, false);
>
> sdma_v5_2_soft_reset(adev);
> - /* unhalt the MEs */
> - sdma_v5_2_enable(adev, true);
> - /* enable sdma ring preemption */
> - sdma_v5_2_ctx_switch_enable(adev, true);
>
> - /* start the gfx rings and rlc compute queues */
> + /* Soft reset supposes to disable the dma engine and preemption.
> + * Now start the gfx rings and rlc compute queues.
> + */
> r = sdma_v5_2_gfx_resume(adev);
> if (adev->in_s0ix)
> amdgpu_gfx_off_ctrl(adev, true);
> @@ -1340,8 +1351,8 @@ static int sdma_v5_2_hw_fini(void *handle)
> if (amdgpu_sriov_vf(adev))
> return 0;
>
> - sdma_v5_2_ctx_switch_enable(adev, false);
> - sdma_v5_2_enable(adev, false);
> + sdma_v5_2_ctx_switch_disable_all(adev);
> + sdma_v5_2_halt(adev);
>
> return 0;
> }
> --
> 2.25.1
>
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