[PATCH v3 06/10] drm/msm/A6xx: Use posamble to reset counters on preemption

[Akhil P Oommen]

On Thu, Sep 05, 2024 at 04:51:24PM +0200, Antonino Maniscalco wrote:
> Use the postamble to reset perf counters when switching between rings,
> except when sysprof is enabled, analogously to how they are reset
> between submissions when switching pagetables.
> 
> Signed-off-by: Antonino Maniscalco <antomani103 at gmail.com>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 20 ++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     |  5 +++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 32 +++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/adreno/adreno_gpu.h   |  7 +++++--
>  4 files changed, 61 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index ed0b138a2d66..710ec3ce2923 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -366,7 +366,8 @@ static void a6xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
>  static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
>  		struct a6xx_gpu *a6xx_gpu, struct msm_gpu_submitqueue *queue)
>  {
> -	u64 preempt_offset_priv_secure;
> +	bool sysprof = refcount_read(&a6xx_gpu->base.base.sysprof_active) > 1;
> +	u64 preempt_offset_priv_secure, preempt_postamble;
>  
>  	OUT_PKT7(ring, CP_SET_PSEUDO_REG, 15);
>  
> @@ -398,6 +399,23 @@ static void a6xx_emit_set_pseudo_reg(struct msm_ringbuffer *ring,
>  	/* seems OK to set to 0 to disable it */
>  	OUT_RING(ring, 0);
>  	OUT_RING(ring, 0);
> +
> +	/* if not profiling set postamble to clear perfcounters, else clear it */
> +	if (!sysprof && a6xx_gpu->preempt_postamble_len) {
> +		preempt_postamble = a6xx_gpu->preempt_postamble_iova;
> +
> +		OUT_PKT7(ring, CP_SET_AMBLE, 3);
> +		OUT_RING(ring, lower_32_bits(preempt_postamble));
> +		OUT_RING(ring, upper_32_bits(preempt_postamble));
> +		OUT_RING(ring, CP_SET_AMBLE_2_DWORDS(
> +					a6xx_gpu->preempt_postamble_len) |
> +				CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
> +	} else {

Why do we need this else part?

> +		OUT_PKT7(ring, CP_SET_AMBLE, 3);
> +		OUT_RING(ring, 0);
> +		OUT_RING(ring, 0);
> +		OUT_RING(ring, CP_SET_AMBLE_2_TYPE(KMD_AMBLE_TYPE));
> +	}
>  }
>  
>  static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> index da10060e38dc..b009732c08c5 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> @@ -71,6 +71,11 @@ struct a6xx_gpu {
>  	bool uses_gmem;
>  	bool skip_save_restore;
>  
> +	struct drm_gem_object *preempt_postamble_bo;
> +	void *preempt_postamble_ptr;
> +	uint64_t preempt_postamble_iova;
> +	uint64_t preempt_postamble_len;
> +
>  	struct a6xx_gmu gmu;
>  
>  	struct drm_gem_object *shadow_bo;
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> index 1caff76aca6e..ec44f44d925f 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_preempt.c
> @@ -346,6 +346,28 @@ static int preempt_init_ring(struct a6xx_gpu *a6xx_gpu,
>  	return 0;
>  }
>  
> +static void preempt_prepare_postamble(struct a6xx_gpu *a6xx_gpu)
> +{
> +	u32 *postamble = a6xx_gpu->preempt_postamble_ptr;
> +	u32 count = 0;
> +
> +	postamble[count++] = PKT7(CP_REG_RMW, 3);
> +	postamble[count++] = REG_A6XX_RBBM_PERFCTR_SRAM_INIT_CMD;
> +	postamble[count++] = 0;
> +	postamble[count++] = 1;
> +
> +	postamble[count++] = PKT7(CP_WAIT_REG_MEM, 6);
> +	postamble[count++] = CP_WAIT_REG_MEM_0_FUNCTION(WRITE_EQ);
> +	postamble[count++] = CP_WAIT_REG_MEM_1_POLL_ADDR_LO(
> +				REG_A6XX_RBBM_PERFCTR_SRAM_INIT_STATUS);
> +	postamble[count++] = CP_WAIT_REG_MEM_2_POLL_ADDR_HI(0);
> +	postamble[count++] = CP_WAIT_REG_MEM_3_REF(0x1);
> +	postamble[count++] = CP_WAIT_REG_MEM_4_MASK(0x1);
> +	postamble[count++] = CP_WAIT_REG_MEM_5_DELAY_LOOP_CYCLES(0);

Isn't it better to just replace this with NOP packets when sysprof is
enabled, just before triggering preemption? It will help to have an
immediate effect.

-Akhil

> +
> +	a6xx_gpu->preempt_postamble_len = count;
> +}
> +
>  void a6xx_preempt_fini(struct msm_gpu *gpu)
>  {
>  	struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> @@ -376,6 +398,16 @@ void a6xx_preempt_init(struct msm_gpu *gpu)
>  	a6xx_gpu->uses_gmem = 1;
>  	a6xx_gpu->skip_save_restore = 1;
>  
> +	a6xx_gpu->preempt_postamble_ptr  = msm_gem_kernel_new(gpu->dev,
> +			PAGE_SIZE, MSM_BO_WC | MSM_BO_MAP_PRIV,
> +			gpu->aspace, &a6xx_gpu->preempt_postamble_bo,
> +			&a6xx_gpu->preempt_postamble_iova);
> +
> +	preempt_prepare_postamble(a6xx_gpu);
> +
> +	if (IS_ERR(a6xx_gpu->preempt_postamble_ptr))
> +		goto fail;
> +
>  	timer_setup(&a6xx_gpu->preempt_timer, a6xx_preempt_timer, 0);
>  
>  	return;
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.h b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> index 6b1888280a83..87098567483b 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.h
> @@ -610,12 +610,15 @@ OUT_PKT4(struct msm_ringbuffer *ring, uint16_t regindx, uint16_t cnt)
>  	OUT_RING(ring, PKT4(regindx, cnt));
>  }
>  
> +#define PKT7(opcode, cnt) \
> +	(CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) | \
> +		((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23))
> +
>  static inline void
>  OUT_PKT7(struct msm_ringbuffer *ring, uint8_t opcode, uint16_t cnt)
>  {
>  	adreno_wait_ring(ring, cnt + 1);
> -	OUT_RING(ring, CP_TYPE7_PKT | (cnt << 0) | (PM4_PARITY(cnt) << 15) |
> -		((opcode & 0x7F) << 16) | (PM4_PARITY(opcode) << 23));
> +	OUT_RING(ring, PKT7(opcode, cnt));
>  }
>  
>  struct msm_gpu *a2xx_gpu_init(struct drm_device *dev);
> 
> -- 
> 2.46.0
>