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From: Steven Price <steven.price@arm.com>
To: Rob Herring <robh@kernel.org>,
	Tomeu Vizoso <tomeu.vizoso@collabora.com>,
	Alyssa Rosenzweig <alyssa@rosenzweig.io>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	David Airlie <airlied@linux.ie>, Inki Dae <inki.dae@samsung.com>,
	Joonyoung Shim <jy0922.shim@samsung.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Kukjin Kim <kgene@kernel.org>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Sean Paul <sean@poorly.run>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] drm: shmem: Add drm_gem_shmem_map_offset() wrapper
Date: Mon, 20 May 2019 10:21:09 +0100	[thread overview]
Message-ID: <b4d04dfd-3f45-e456-e944-9c337a6538a5@arm.com> (raw)
In-Reply-To: <20190516202644.GE3851@phenom.ffwll.local>

On 16/05/2019 21:26, Daniel Vetter wrote:
> On Thu, May 16, 2019 at 03:14:46PM +0100, Steven Price wrote:
>> Provide a wrapper for drm_gem_map_offset() for clients of shmem. This
>> wrapper provides the correct semantics for the drm_gem_shmem_mmap()
>> callback.
>>
>> Signed-off-by: Steven Price <steven.price@arm.com>
>> ---
>>  drivers/gpu/drm/drm_gem_shmem_helper.c | 20 ++++++++++++++++++++
>>  include/drm/drm_gem_shmem_helper.h     |  2 ++
>>  2 files changed, 22 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
>> index 1ee208c2c85e..9dbebc4897d1 100644
>> --- a/drivers/gpu/drm/drm_gem_shmem_helper.c
>> +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
>> @@ -400,6 +400,26 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
>>  }
>>  EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
>>  
>> +/**
>> + * drm_gem_map_offset - return the fake mmap offset for a gem object
>> + * @file: drm file-private structure containing the gem object
>> + * @dev: corresponding drm_device
>> + * @handle: gem object handle
>> + * @offset: return location for the fake mmap offset
>> + *
>> + * This provides an offset suitable for user space to return to the
>> + * drm_gem_shmem_mmap() callback via an mmap() call.
>> + *
>> + * Returns:
>> + * 0 on success or a negative error code on failure.
>> + */
>> +int drm_gem_shmem_map_offset(struct drm_file *file, struct drm_device *dev,
>> +			     u32 handle, u64 *offset)
>> +{
>> +	return drm_gem_map_offset(file, dev, handle, offset);
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gem_shmem_map_offset);
> 
> Not seeing the point of this mapper, since drm_gem_shmem_map_offset isn't
> speficic at all. It works for dumb, shmem, cma and private objects all
> equally well. I'd drop this and just directly call the underlying thing,
> no need to layer helpers.
> -Daniel

Ok, I'll drop it. I may have misunderstood, but I think Chris Wilson was
asking for it because shmem is the source of the particular requirements
of what can be mmap()d. But I think a helper can be added very easily if
anything changes, so this patch is probably premature.

I'll resend the series with this patch dropped.

Thanks,
Steve

  reply	other threads:[~2019-05-20  9:21 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-16 14:14 [PATCH v2 0/3] drm/panfrost: drm_gem_map_offset() helper Steven Price
2019-05-16 14:14 ` [PATCH v2 1/3] drm/gem: Rename drm_gem_dumb_map_offset() to drm_gem_map_offset() Steven Price
2019-05-16 20:25   ` Daniel Vetter
2019-05-16 14:14 ` [PATCH v2 2/3] drm: shmem: Add drm_gem_shmem_map_offset() wrapper Steven Price
2019-05-16 20:26   ` Daniel Vetter
2019-05-20  9:21     ` Steven Price [this message]
2019-05-16 14:14 ` [PATCH v2 3/3] drm/panfrost: Use drm_gem_shmem_map_offset() Steven Price
2019-05-16 15:36 ` [PATCH v2 0/3] drm/panfrost: drm_gem_map_offset() helper Alyssa Rosenzweig

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