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Date: Sun, 01 Aug 2021 23:29:59 -0700
Message-ID: <87pmuw5pg8.wl-ashutosh.dixit@intel.com>
From: "Dixit, Ashutosh" <ashutosh.dixit@intel.com>
In-Reply-To: <20210730085348.2326899-3-matthew.auld@intel.com>
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Subject: Re: [Intel-gfx] [PATCH i-g-t v3 03/11] lib/i915/gem_mman: add fixed
 mode to gem_mmap_offset__cpu
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To: Matthew Auld <matthew.auld@intel.com>
Cc: igt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Daniel Vetter <daniel.vetter@ffwll.ch>, Ramalingam C <ramalingam.c@intel.com>
List-ID: <igt-dev@lists.freedesktop.org>

On Fri, 30 Jul 2021 01:53:40 -0700, Matthew Auld wrote:
>
> On discrete we only support the new fixed mode.
>
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Ramalingam C <ramalingam.c@intel.com>
> ---
>  lib/i915/gem_mman.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c
> index c432bb16..563a7ccf 100644
> --- a/lib/i915/gem_mman.c
> +++ b/lib/i915/gem_mman.c
> @@ -474,8 +474,14 @@ void *gem_mmap__cpu(int fd, uint32_t handle, uint64_t offset, uint64_t size, uns
>  void *__gem_mmap_offset__cpu(int fd, uint32_t handle, uint64_t offset,
>			     uint64_t size, unsigned prot)
>  {
> -	return __gem_mmap_offset(fd, handle, offset, size, prot,
> +	void *ptr;
> +
> +	ptr = __gem_mmap_offset(fd, handle, offset, size, prot,
>				 I915_MMAP_OFFSET_WB);
> +	if (!ptr)
> +		ptr = __gem_mmap_offset__fixed(fd, handle, offset, size, prot);
> +
> +	return ptr;

Imo there's some asymmetry here. If we are adding fixed mode to
mmap__device_coherent (in the previous patch) then we should also be adding
it to mmap__cpu_coherent (as before). Or, if we are adding fixed mode to
__gem_mmap_offset__cpu we should also be adding it to
__gem_mmap_offset__wc. Thanks.