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Subject: Re: [PATCH 03/11] drm/panfrost: Use xarray and helpers for depedency
 tracking
To:     Daniel Vetter <daniel@ffwll.ch>
Cc:     Daniel Vetter <daniel.vetter@ffwll.ch>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Luben Tuikov <luben.tuikov@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Lee Jones <lee.jones@linaro.org>,
        Rob Herring <robh@kernel.org>,
        Tomeu Vizoso <tomeu.vizoso@collabora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
        Daniel Vetter <daniel.vetter@intel.com>
References: <20210521090959.1663703-1-daniel.vetter@ffwll.ch>
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 <2054fee7-dcd2-a4fa-5d50-7fe6f1b474be@arm.com>
 <YLfTGbb52KtbPk7q@phenom.ffwll.local>
From:   Steven Price <steven.price@arm.com>
Message-ID: <e9081dec-0225-a24d-261c-3ab750b29614@arm.com>
Date:   Thu, 3 Jun 2021 08:48:04 +0100
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On 02/06/2021 19:51, Daniel Vetter wrote:
> On Wed, Jun 02, 2021 at 03:06:50PM +0100, Steven Price wrote:
>> On 21/05/2021 10:09, Daniel Vetter wrote:
[...]
>>> +	if (!xa_empty(&job->deps))
>>> +		return xa_erase(&job->deps, job->last_dep++);
>>
>> Rather than tracking last_dep separately this could be written using
>> xa_find():
>>
>>     if (xa_find(&job->deps, &i, ULONG_MAX, XA_PRESENT))
>> 	return xa_erase(&job->deps, &i);
> 
> I copypasted this from other drivers, imo consistency is better than
> looking pretty. I think eventually we should stuff this as optional
> helpers into drm/scheduler.
> 
> Also yours walks the xa twice.

Agreed this isn't as efficient (I was somewhat disappointed xarray
doesn't expose a "get and remove the first element" API). Moving this
into drm/scheduler seems like the right long term solution - so matching
other drivers first is a good move.

Thanks,

Steve