[RFC PATCH v2 10/17] WIP: gpu: host1x: Add no-recovery mode

[Mikko Perttunen]

On 9/11/20 7:40 PM, Dmitry Osipenko wrote:
> 05.09.2020 13:34, Mikko Perttunen пишет:
>> +	} else {
>> +		struct host1x_job *failed_job = job;
>> +
>> +		host1x_job_dump(dev, job);
>> +
>> +		host1x_syncpt_set_locked(job->syncpt);
>> +		failed_job->cancelled = true;
>> +
>> +		list_for_each_entry_continue(job, &cdma->sync_queue, list) {
>> +			unsigned int i;
>> +
>> +			if (job->syncpt != failed_job->syncpt)
>> +				continue;
>> +
>> +			for (i = 0; i < job->num_slots; i++) {
>> +				unsigned int slot = (job->first_get/8 + i) %
>> +						    HOST1X_PUSHBUFFER_SLOTS;
>> +				u32 *mapped = cdma->push_buffer.mapped;
>> +
>> +				mapped[2*slot+0] = 0x1bad0000;
>> +				mapped[2*slot+1] = 0x1bad0000;
> 
> The 0x1bad0000 is a valid memory address on Tegra20.
> 
> The 0x60000000 is invalid phys address for all hardware generations.
> It's used by grate-kernel [1] and VDE driver [2]. Note that the 0x6 <<
> 28 is also invalid Host1x opcode, while 0x1 should break CDMA parser
> during of PB debug-dumping.
> 
> [1]
> https://github.com/grate-driver/linux/blob/master/drivers/gpu/drm/tegra/gem.h#L16
> 
> [2]
> https://elixir.bootlin.com/linux/v5.9-rc4/source/drivers/staging/media/tegra-vde/iommu.c#L99
> 
> The VDE driver reserves the trapping IOVA addresses, I assume the Host1x
> driver should do the same.
> 

The 0x1bad0000's are not intended to be memory addresses, they are NOOP 
opcodes (INCR of 0 words to offset 0xbad). I'll fix this to use proper 
functions to construct the opcodes and add some comments. These need to 
be NOOP opcodes so the command parser skips over these "cancelled" jobs 
when the channel is resumed.

BTW, 0x60000000 is valid on Tegra194 and later.

Mikko