In_atomic() isnot encouraged to be used to judge if sleep is possible, see the macros of it
#define in_atomic() (preept_count() != 0)
/Monk
-----Original Message-----
From: Kuehling, Felix
Sent: 2018å¹´3æ??1æ?¥ 23:50
To: amd-gfx at lists.freedesktop.org; Liu, Monk <Monk.Liu at amd.com>
Subject: Re: [PATCH] drm/amdgpu: try again kiq access if not in IRQ(v2)
On 2018-02-28 02:27 AM, Monk Liu wrote:
> sometimes GPU is switched to other VFs and won't swich back soon, so
> the kiq reg access will not signal within a short period, instead of
> busy waiting a long time(MAX_KEQ_REG_WAIT) and returning TMO we can
> istead sleep 5ms and try again later (non irq context)
>
> And since the waiting in kiq_r/weg is busy wait, so MAX_KIQ_REG_WAIT
> shouldn't set to a long time, set it to 10ms is more appropriate.
>
> if gpu already in reset state, don't retry the KIQ reg access
> otherwise it would always hang because KIQ was already die usually.
>
> v2:
> replace schedule() with msleep() for the wait
>
> Change-Id: I8fc807ce85a8d30d2b50153f3f3a6eda344ef994
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> index b832651..1672f5b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
> @@ -22,7 +22,7 @@
> */
>
> #include "amdgpu.h"
> -#define MAX_KIQ_REG_WAIT 100000000 /* in usecs */
> +#define MAX_KIQ_REG_WAIT 10000 /* in usecs, 10ms */
>
> uint64_t amdgpu_csa_vaddr(struct amdgpu_device *adev) { @@ -152,9
> +152,14 @@ uint32_t amdgpu_virt_kiq_rreg(struct amdgpu_device *adev, uint32_t reg)
> amdgpu_ring_commit(ring);
> spin_unlock_irqrestore(&kiq->ring_lock, flags);
>
> +retry_read:
> r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
> if (r < 1) {
> DRM_ERROR("wait for kiq fence error: %ld\n", r);
> + if (!in_interrupt() && !adev->in_gpu_reset) {
You should check in_atomic here. Because it's invalid to sleep in atomic context (e.g. while holding a spin lock) even when not in an interrupt.
This seems to happen a lot for indirect register access, e.g.
soc15_pcie_rreg.
Regards,
 Felix
> + msleep(5);
> + goto retry_read;
> + }
> return ~0;
> }
> val = adev->wb.wb[adev->virt.reg_val_offs];
> @@ -179,9 +184,15 @@ void amdgpu_virt_kiq_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v)
> amdgpu_ring_commit(ring);
> spin_unlock_irqrestore(&kiq->ring_lock, flags);
>
> +retry_write:
> r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
> - if (r < 1)
> + if (r < 1) {
> DRM_ERROR("wait for kiq fence error: %ld\n", r);
> + if (!in_interrupt() && !adev->in_gpu_reset) {
> + msleep(5);
> + goto retry_write;
> + }
> + }
> }
>
> /**
