[PATCH] drm/amdkfd: Disable Packet Manager in non HWS mode except Hawaii

[Kuehling, Felix]

On 2019-04-17 4:54 p.m., Zhao, Yong wrote:
> The packet manager is only needed for HWS mode, as well as Hawaii in non
> HWS mode. So only initialize it under those scenarios. This is useful
> especially for emulation environment when things are slow.

I never thought of packet manager initialization as something expensive. 
Why does this matter? In emulation, the GPU is slow, but the CPU should 
be OK. Packet manager initialization doesn't do any waiting for the GPU, 
so I don't see how this would have any measurable impact.

Anyway, see one cosmetic comment inline.


>
> Change-Id: Iedfa07c94241e3252463e1e5ea537543c2ccef03
> Signed-off-by: Yong Zhao <Yong.Zhao at amd.com>
> ---
>   .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.c   | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> index 1d6b15788ebf..ec83914d9867 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> @@ -911,13 +911,22 @@ static void uninitialize(struct device_queue_manager *dqm)
>   
>   static int start_nocpsch(struct device_queue_manager *dqm)
>   {
> +	int ret = 0;

checkpatch.pl would complain that there should be an empty line after 
variable declarations.


>   	init_interrupts(dqm);
> -	return pm_init(&dqm->packets, dqm);
> +	/* Cache flushing on Hawaii in non HWS mode is done through packet
> +	 * manager (PM), so we need to initialize PM for Hawaii.
> +	 */
> +	if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
> +		ret = pm_init(&dqm->packets, dqm);
> +
> +	return ret;
>   }
>   
>   static int stop_nocpsch(struct device_queue_manager *dqm)
>   {
> -	pm_uninit(&dqm->packets);
> +	if (dqm->dev->device_info->asic_family == CHIP_HAWAII)
> +		pm_uninit(&dqm->packets);
> +
>   	return 0;
>   }
>