[AMD Official Use Only - Internal Distribution Only]
Hi ,Yintian & Christian
I still don't understand why we need this complicated change here . Why can
not just allocate few more extra space in the ring for each read and use the
space to store the output value ?
Regards
Shaoyun.liu
-----Original Message-----
From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> On Behalf Of Christian
König
Sent: Wednesday, April 22, 2020 8:42 AM
To: Tao, Yintian <yintian....@amd.com>; Liu, Monk <monk....@amd.com>; Kuehling,
Felix <felix.kuehl...@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/amdgpu: request reg_val_offs each kiq read reg
Am 22.04.20 um 14:36 schrieb Yintian Tao:
> According to the current kiq read register method, there will be race
> condition when using KIQ to read register if multiple clients want to
> read at same time just like the expample below:
> 1. client-A start to read REG-0 throguh KIQ 2. client-A poll the
> seqno-0 3. client-B start to read REG-1 through KIQ 4. client-B poll
> the seqno-1 5. the kiq complete these two read operation 6. client-A
> to read the register at the wb buffer and
> get REG-1 value
>
> Therefore, use amdgpu_device_wb_get() to request reg_val_offs for each
> kiq read register.
>
> v2: fix the error remove
>
> Signed-off-by: Yintian Tao <yt...@amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu.h | 2 +-
> drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | 19 ++++++++++-------
> drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h | 1 -
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h | 5 +++--
> drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c | 7 +++---
> drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c | 7 +++---
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 27 ++++++++++++++++--------
> 7 files changed, 41 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> index 4e1d4cfe7a9f..7ee5a4da398a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> @@ -526,7 +526,7 @@ static inline void amdgpu_set_ib_value(struct
> amdgpu_cs_parser *p,
> /*
> * Writeback
> */
> -#define AMDGPU_MAX_WB 128 /* Reserve at most 128 WB slots for
> amdgpu-owned rings. */
> +#define AMDGPU_MAX_WB 256 /* Reserve at most 256 WB slots for
> amdgpu-owned rings. */
>
> struct amdgpu_wb {
> struct amdgpu_bo *wb_obj;
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> index ea576b4260a4..d5a59d7c48d6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> @@ -304,10 +304,6 @@ int amdgpu_gfx_kiq_init_ring(struct amdgpu_device
> *adev,
>
> spin_lock_init(&kiq->ring_lock);
>
> - r = amdgpu_device_wb_get(adev, &kiq->reg_val_offs);
> - if (r)
> - return r;
> -
> ring->adev = NULL;
> ring->ring_obj = NULL;
> ring->use_doorbell = true;
> @@ -331,7 +327,6 @@ int amdgpu_gfx_kiq_init_ring(struct amdgpu_device
> *adev,
>
> void amdgpu_gfx_kiq_free_ring(struct amdgpu_ring *ring)
> {
> - amdgpu_device_wb_free(ring->adev, ring->adev->gfx.kiq.reg_val_offs);
> amdgpu_ring_fini(ring);
> }
>
> @@ -672,15 +667,20 @@ uint32_t amdgpu_kiq_rreg(struct amdgpu_device *adev,
> uint32_t reg)
> {
> signed long r, cnt = 0;
> unsigned long flags;
> - uint32_t seq;
> + uint32_t seq, reg_val_offs = 0, value = 0;
> struct amdgpu_kiq *kiq = &adev->gfx.kiq;
> struct amdgpu_ring *ring = &kiq->ring;
>
> BUG_ON(!ring->funcs->emit_rreg);
>
> spin_lock_irqsave(&kiq->ring_lock, flags);
> + if (amdgpu_device_wb_get(adev, ®_val_offs)) {
> + spin_unlock_irqrestore(&kiq->ring_lock, flags);
> + pr_err("critical bug! too more kiq readers\n");
Typo here, this should probably read "too many kiq readers".
But I don't think we need the error message here anyway, the failed_kiq_read
label also prints an error.
With that fixed the patch is Reviewed-by: Christian König
<christian.koe...@amd.com>.
Thanks,
Christian.
> + goto failed_kiq_read;
> + }
> amdgpu_ring_alloc(ring, 32);
> - amdgpu_ring_emit_rreg(ring, reg);
> + amdgpu_ring_emit_rreg(ring, reg, reg_val_offs);
> amdgpu_fence_emit_polling(ring, &seq);
> amdgpu_ring_commit(ring);
> spin_unlock_irqrestore(&kiq->ring_lock, flags); @@ -707,7 +707,10
> @@ uint32_t amdgpu_kiq_rreg(struct amdgpu_device *adev, uint32_t reg)
> if (cnt > MAX_KIQ_REG_TRY)
> goto failed_kiq_read;
>
> - return adev->wb.wb[kiq->reg_val_offs];
> + mb();
> + value = adev->wb.wb[reg_val_offs];
> + amdgpu_device_wb_free(adev, reg_val_offs);
> + return value;
>
> failed_kiq_read:
> pr_err("failed to read reg:%x\n", reg); diff --git
> a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h
> index 634746829024..ee698f0246d8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.h
> @@ -103,7 +103,6 @@ struct amdgpu_kiq {
> struct amdgpu_ring ring;
> struct amdgpu_irq_src irq;
> const struct kiq_pm4_funcs *pmf;
> - uint32_t reg_val_offs;
> };
>
> /*
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> index f61664ee4940..137d3d2b46e8 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> @@ -181,7 +181,8 @@ struct amdgpu_ring_funcs {
> void (*end_use)(struct amdgpu_ring *ring);
> void (*emit_switch_buffer) (struct amdgpu_ring *ring);
> void (*emit_cntxcntl) (struct amdgpu_ring *ring, uint32_t flags);
> - void (*emit_rreg)(struct amdgpu_ring *ring, uint32_t reg);
> + void (*emit_rreg)(struct amdgpu_ring *ring, uint32_t reg,
> + uint32_t reg_val_offs);
> void (*emit_wreg)(struct amdgpu_ring *ring, uint32_t reg, uint32_t val);
> void (*emit_reg_wait)(struct amdgpu_ring *ring, uint32_t reg,
> uint32_t val, uint32_t mask); @@ -265,7 +266,7 @@
> struct
> amdgpu_ring {
> #define amdgpu_ring_emit_hdp_flush(r) (r)->funcs->emit_hdp_flush((r))
> #define amdgpu_ring_emit_switch_buffer(r)
> (r)->funcs->emit_switch_buffer((r))
> #define amdgpu_ring_emit_cntxcntl(r, d)
> (r)->funcs->emit_cntxcntl((r), (d)) -#define amdgpu_ring_emit_rreg(r,
> d) (r)->funcs->emit_rreg((r), (d))
> +#define amdgpu_ring_emit_rreg(r, d, o) (r)->funcs->emit_rreg((r),
> +(d), (o))
> #define amdgpu_ring_emit_wreg(r, d, v) (r)->funcs->emit_wreg((r), (d), (v))
> #define amdgpu_ring_emit_reg_wait(r, d, v, m)
> (r)->funcs->emit_reg_wait((r), (d), (v), (m))
> #define amdgpu_ring_emit_reg_write_reg_wait(r, d0, d1, v, m)
> (r)->funcs->emit_reg_write_reg_wait((r), (d0), (d1), (v), (m)) diff
> --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> index 0a03e2ad5d95..0a3d3bc9d441 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
> @@ -7594,7 +7594,8 @@ static void gfx_v10_0_ring_emit_frame_cntl(struct
> amdgpu_ring *ring, bool start,
> amdgpu_ring_write(ring, v | FRAME_CMD(start ? 0 : 1));
> }
>
> -static void gfx_v10_0_ring_emit_rreg(struct amdgpu_ring *ring,
> uint32_t reg)
> +static void gfx_v10_0_ring_emit_rreg(struct amdgpu_ring *ring, uint32_t reg,
> + uint32_t reg_val_offs)
> {
> struct amdgpu_device *adev = ring->adev;
> struct amdgpu_kiq *kiq = &adev->gfx.kiq; @@ -7606,9 +7607,9 @@
> static void gfx_v10_0_ring_emit_rreg(struct amdgpu_ring *ring, uint32_t reg)
> amdgpu_ring_write(ring, reg);
> amdgpu_ring_write(ring, 0);
> amdgpu_ring_write(ring, lower_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> amdgpu_ring_write(ring, upper_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> }
>
> static void gfx_v10_0_ring_emit_wreg(struct amdgpu_ring *ring,
> uint32_t reg, diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> index fc6c2f2bc76c..ccfa65c3cb5a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c
> @@ -6383,7 +6383,8 @@ static void gfx_v8_0_ring_emit_patch_cond_exec(struct
> amdgpu_ring *ring, unsigne
> ring->ring[offset] = (ring->ring_size >> 2) - offset + cur;
> }
>
> -static void gfx_v8_0_ring_emit_rreg(struct amdgpu_ring *ring,
> uint32_t reg)
> +static void gfx_v8_0_ring_emit_rreg(struct amdgpu_ring *ring, uint32_t reg,
> + uint32_t reg_val_offs)
> {
> struct amdgpu_device *adev = ring->adev;
> struct amdgpu_kiq *kiq = &adev->gfx.kiq; @@ -6395,9 +6396,9 @@
> static void gfx_v8_0_ring_emit_rreg(struct amdgpu_ring *ring, uint32_t reg)
> amdgpu_ring_write(ring, reg);
> amdgpu_ring_write(ring, 0);
> amdgpu_ring_write(ring, lower_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> amdgpu_ring_write(ring, upper_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> }
>
> static void gfx_v8_0_ring_emit_wreg(struct amdgpu_ring *ring,
> uint32_t reg, diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 84fcf842316d..0b706f908d9a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -4043,13 +4043,19 @@ static uint64_t gfx_v9_0_kiq_read_clock(struct
> amdgpu_device *adev)
> {
> signed long r, cnt = 0;
> unsigned long flags;
> - uint32_t seq;
> + uint32_t seq, reg_val_offs = 0;
> + uint64_t value = 0;
> struct amdgpu_kiq *kiq = &adev->gfx.kiq;
> struct amdgpu_ring *ring = &kiq->ring;
>
> BUG_ON(!ring->funcs->emit_rreg);
>
> spin_lock_irqsave(&kiq->ring_lock, flags);
> + if (amdgpu_device_wb_get(adev, ®_val_offs)) {
> + spin_unlock_irqrestore(&kiq->ring_lock, flags);
> + pr_err("critical bug! too more kiq readers\n");
> + goto failed_kiq_read;
> + }
> amdgpu_ring_alloc(ring, 32);
> amdgpu_ring_write(ring, PACKET3(PACKET3_COPY_DATA, 4));
> amdgpu_ring_write(ring, 9 | /* src: register*/
> @@ -4059,9 +4065,9 @@ static uint64_t gfx_v9_0_kiq_read_clock(struct
> amdgpu_device *adev)
> amdgpu_ring_write(ring, 0);
> amdgpu_ring_write(ring, 0);
> amdgpu_ring_write(ring, lower_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> amdgpu_ring_write(ring, upper_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> amdgpu_fence_emit_polling(ring, &seq);
> amdgpu_ring_commit(ring);
> spin_unlock_irqrestore(&kiq->ring_lock, flags); @@ -4088,8 +4094,11
> @@ static uint64_t gfx_v9_0_kiq_read_clock(struct amdgpu_device *adev)
> if (cnt > MAX_KIQ_REG_TRY)
> goto failed_kiq_read;
>
> - return (uint64_t)adev->wb.wb[kiq->reg_val_offs] |
> - (uint64_t)adev->wb.wb[kiq->reg_val_offs + 1 ] << 32ULL;
> + mb();
> + value = (uint64_t)adev->wb.wb[reg_val_offs] |
> + (uint64_t)adev->wb.wb[reg_val_offs + 1 ] << 32ULL;
> + amdgpu_device_wb_free(adev, reg_val_offs);
> + return value;
>
> failed_kiq_read:
> pr_err("failed to read gpu clock\n"); @@ -5482,10 +5491,10 @@
> static void gfx_v9_0_ring_emit_patch_cond_exec(struct amdgpu_ring *ring,
> unsigne
> ring->ring[offset] = (ring->ring_size>>2) - offset + cur;
> }
>
> -static void gfx_v9_0_ring_emit_rreg(struct amdgpu_ring *ring,
> uint32_t reg)
> +static void gfx_v9_0_ring_emit_rreg(struct amdgpu_ring *ring, uint32_t reg,
> + uint32_t reg_val_offs)
> {
> struct amdgpu_device *adev = ring->adev;
> - struct amdgpu_kiq *kiq = &adev->gfx.kiq;
>
> amdgpu_ring_write(ring, PACKET3(PACKET3_COPY_DATA, 4));
> amdgpu_ring_write(ring, 0 | /* src: register*/
> @@ -5494,9 +5503,9 @@ static void gfx_v9_0_ring_emit_rreg(struct amdgpu_ring
> *ring, uint32_t reg)
> amdgpu_ring_write(ring, reg);
> amdgpu_ring_write(ring, 0);
> amdgpu_ring_write(ring, lower_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> amdgpu_ring_write(ring, upper_32_bits(adev->wb.gpu_addr +
> - kiq->reg_val_offs * 4));
> + reg_val_offs * 4));
> }
>
> static void gfx_v9_0_ring_emit_wreg(struct amdgpu_ring *ring,
> uint32_t reg,
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