linux-kernel - Re: [PATCH 04/10] gpu: host1x: Lock classes during job submission

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Date:   Tue, 7 Nov 2017 14:28:37 +0200
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Dmitry Osipenko <digetx@...il.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        thierry.reding@...il.com, jonathanh@...dia.com
Cc:     dri-devel@...ts.freedesktop.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/10] gpu: host1x: Lock classes during job submission

On 05.11.2017 18:46, Dmitry Osipenko wrote:
> On 05.11.2017 14:01, Mikko Perttunen wrote:
 >> ...
>>
>> +static int mlock_id_for_class(unsigned int class)
>> +{
>> +#if HOST1X_HW >= 6
>> +	switch (class)
>> +	{
>> +	case HOST1X_CLASS_HOST1X:
>> +		return 0;
>> +	case HOST1X_CLASS_VIC:
>> +		return 17;
>
> What is the meaning of returned ID values that you have defined here? Why VIC
> should have different ID on T186?

On T186, MLOCKs are not "generic" - the HW knows that each MLOCK 
corresponds to a specific class. Therefore we must map that correctly.

>
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +#else
>> +	switch (class)
>> +	{
>> +	case HOST1X_CLASS_HOST1X:
>> +		return 0;
>> +	case HOST1X_CLASS_GR2D:
>> +		return 1;
>> +	case HOST1X_CLASS_GR2D_SB:
>> +		return 2;
>
> Note that we are allowing to switch 2d classes in the same jobs context and
> currently jobs class is somewhat hardcoded to GR2D.
>
> Even though that GR2D and GR2D_SB use different register banks, is it okay to
> trigger execution of different classes simultaneously? Would syncpoint
> differentiate classes on OP_DONE event?

Good point, we might need to use the same lock for these two.

>
> I suppose that MLOCK (the module lock) implies the whole module locking,
> wouldn't it make sense to just use the module ID's defined in the TRM?

Can you point out where these are defined?

Mikko