From: Boris Brezillon <boris.brezillon@collabora.com>
To: Steven Price <steven.price@arm.com>
Cc: "Liviu Dudau" <liviu.dudau@arm.com>,
"Adrián Larumbe" <adrian.larumbe@collabora.com>,
dri-devel@lists.freedesktop.org, kernel@collabora.com,
"Eric Smith" <eric.smith@collabora.com>
Subject: Re: [PATCH v2 4/4] drm/panthor: Fix an off-by-one in the heap context retrieval logic
Date: Thu, 2 May 2024 16:15:03 +0200 [thread overview]
Message-ID: <20240502161503.00f4e3c9@collabora.com> (raw)
In-Reply-To: <791a81bf-323c-40dc-ab51-2d909adcb90b@arm.com>
On Thu, 2 May 2024 15:03:51 +0100
Steven Price <steven.price@arm.com> wrote:
> On 30/04/2024 12:28, Boris Brezillon wrote:
> > ID 0 is reserved to encode 'no-tiler-heap', the heap ID range is
> > [1:MAX_HEAPS_PER_POOL], which we occasionally need to turn into an index
> > in the [0:MAX_HEAPS_PER_POOL-1] when we want to access the context object.
>
> This might be a silly question, but do we need ID 0 to be
> "no-tiler-heap"? Would it be easier to e.g. use a negative number for
> that situation and avoid all the off-by-one problems?
>
> I'm struggling to find the code which needs the 0 value to be special -
> where is it exactly that we encode this "no-tiler-heap" value?
Hm, I thought we were passing the heap handle to the group creation
ioctl, but heap queue/heap association is actually done through a CS
instruction, so I guess you have a point. The only thing that makes a
bit hesitant is that handle=0 is reserved for all other kind of handles
we return, and I think I'd prefer to keep it the same for heap handles.
This being said, we could do the `+- 1` in
panthor_ioctl_tiler_heap_{create,destroy}() to keep things simple in
panthor_heap.c.
next prev parent reply other threads:[~2024-05-02 14:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-30 11:28 [PATCH v2 0/4] drm/panthor: Collection of tiler heap related fixes Boris Brezillon
2024-04-30 11:28 ` [PATCH v2 1/4] drm/panthor: Fix tiler OOM handling to allow incremental rendering Boris Brezillon
2024-04-30 15:27 ` Liviu Dudau
2024-05-02 14:03 ` Steven Price
2024-04-30 11:28 ` [PATCH v2 2/4] drm/panthor: Make sure the tiler initial/max chunks are consistent Boris Brezillon
2024-04-30 15:31 ` Liviu Dudau
2024-05-02 14:03 ` Steven Price
2024-04-30 11:28 ` [PATCH v2 3/4] drm/panthor: Relax the constraints on the tiler chunk size Boris Brezillon
2024-04-30 13:08 ` Adrián Larumbe
2024-05-02 14:03 ` Steven Price
2024-04-30 16:10 ` Liviu Dudau
2024-04-30 11:28 ` [PATCH v2 4/4] drm/panthor: Fix an off-by-one in the heap context retrieval logic Boris Brezillon
2024-04-30 16:40 ` Liviu Dudau
2024-04-30 17:07 ` Boris Brezillon
2024-05-02 14:03 ` Steven Price
2024-05-02 14:15 ` Boris Brezillon [this message]
2024-05-02 14:26 ` Steven Price
2024-05-02 14:36 ` Boris Brezillon
2024-05-02 14:47 ` Boris Brezillon
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