linux-kernel - Re: [PATCH 07/83] drm/radeon: Add kfd-->kgd interface of locking srbm_gfx

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Date:	Fri, 11 Jul 2014 12:34:38 -0400
From:	Jerome Glisse <j.glisse@...il.com>
To:	Oded Gabbay <oded.gabbay@...il.com>
Cc:	David Airlie <airlied@...ux.ie>,
	Alex Deucher <alexander.deucher@....com>,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	John Bridgman <John.Bridgman@....com>,
	Andrew Lewycky <Andrew.Lewycky@....com>,
	Joerg Roedel <joro@...tes.org>,
	Oded Gabbay <oded.gabbay@....com>,
	Christian König <christian.koenig@....com>
Subject: Re: [PATCH 07/83] drm/radeon: Add kfd-->kgd interface of locking
 srbm_gfx_cntl register

On Fri, Jul 11, 2014 at 12:50:07AM +0300, Oded Gabbay wrote:
> This patch adds a new interface to kfd2kgd_calls structure, which
> allows the kfd to lock and unlock the srbm_gfx_cntl register

Why does kfd needs to lock this register if kfd can not access
any of those register ? This sounds broken to me, exposing a
driver internal mutex to another driver is not something i am
fan of.

Cheers,
Jérôme

> 
> Signed-off-by: Oded Gabbay <oded.gabbay@....com>
> ---
>  drivers/gpu/drm/radeon/radeon_kfd.c | 20 ++++++++++++++++++++
>  include/linux/radeon_kfd.h          |  4 ++++
>  2 files changed, 24 insertions(+)
> 
> diff --git a/drivers/gpu/drm/radeon/radeon_kfd.c b/drivers/gpu/drm/radeon/radeon_kfd.c
> index 66ee36b..594020e 100644
> --- a/drivers/gpu/drm/radeon/radeon_kfd.c
> +++ b/drivers/gpu/drm/radeon/radeon_kfd.c
> @@ -43,6 +43,10 @@ static void unkmap_mem(struct kgd_dev *kgd, struct kgd_mem *mem);
>  
>  static uint64_t get_vmem_size(struct kgd_dev *kgd);
>  
> +static void lock_srbm_gfx_cntl(struct kgd_dev *kgd);
> +static void unlock_srbm_gfx_cntl(struct kgd_dev *kgd);
> +
> +
>  static const struct kfd2kgd_calls kfd2kgd = {
>  	.allocate_mem = allocate_mem,
>  	.free_mem = free_mem,
> @@ -51,6 +55,8 @@ static const struct kfd2kgd_calls kfd2kgd = {
>  	.kmap_mem = kmap_mem,
>  	.unkmap_mem = unkmap_mem,
>  	.get_vmem_size = get_vmem_size,
> +	.lock_srbm_gfx_cntl = lock_srbm_gfx_cntl,
> +	.unlock_srbm_gfx_cntl = unlock_srbm_gfx_cntl,
>  };
>  
>  static const struct kgd2kfd_calls *kgd2kfd;
> @@ -233,3 +239,17 @@ static uint64_t get_vmem_size(struct kgd_dev *kgd)
>  
>  	return rdev->mc.real_vram_size;
>  }
> +
> +static void lock_srbm_gfx_cntl(struct kgd_dev *kgd)
> +{
> +	struct radeon_device *rdev = (struct radeon_device *)kgd;
> +
> +	mutex_lock(&rdev->srbm_mutex);
> +}
> +
> +static void unlock_srbm_gfx_cntl(struct kgd_dev *kgd)
> +{
> +	struct radeon_device *rdev = (struct radeon_device *)kgd;
> +
> +	mutex_unlock(&rdev->srbm_mutex);
> +}
> diff --git a/include/linux/radeon_kfd.h b/include/linux/radeon_kfd.h
> index c7997d4..40b691c 100644
> --- a/include/linux/radeon_kfd.h
> +++ b/include/linux/radeon_kfd.h
> @@ -81,6 +81,10 @@ struct kfd2kgd_calls {
>  	void (*unkmap_mem)(struct kgd_dev *kgd, struct kgd_mem *mem);
>  
>  	uint64_t (*get_vmem_size)(struct kgd_dev *kgd);
> +
> +	/* SRBM_GFX_CNTL mutex */
> +	void (*lock_srbm_gfx_cntl)(struct kgd_dev *kgd);
> +	void (*unlock_srbm_gfx_cntl)(struct kgd_dev *kgd);
>  };
>  
>  bool kgd2kfd_init(unsigned interface_version,
> -- 
> 1.9.1
> 
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