Re: drm/radeon: "ring test failed" on PA-RISC Linux

From: Alex Ivanov <gnidorah@p0n4ik.tk>
To: Alex Deucher <alexdeucher@gmail.com>
Cc: Maling list - DRI developers <dri-devel@lists.freedesktop.org>
Subject: Re: drm/radeon: "ring test failed" on PA-RISC Linux
Date: Tue, 17 Sep 2013 23:33:20 +0400	[thread overview]
Message-ID: <E837CF38-7104-442E-941B-6B64ED876F82@p0n4ik.tk> (raw)
In-Reply-To: <CADnq5_MvvO-K8vu8euc0dfUhXDAXgjb43H-Tx3OjPVN9OQE-8w@mail.gmail.com>

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17.09.2013, в 18:24, Alex Deucher <alexdeucher@gmail.com> написал(а):

> On Tue, Sep 17, 2013 at 5:23 AM, Alex Ivanov <gnidorah@p0n4ik.tk> wrote:
>> Alex,
>> 
>> 10.09.2013, в 16:37, Alex Deucher <alexdeucher@gmail.com> написал(а):
>> 
>>> The dummy page isn't really going to help much.  That page is just
>>> used as a safety placeholder for gart entries that aren't mapped on
>>> the GPU.  TTM (drivers/gpu/drm/ttm) actually does the allocation of
>>> the backing pages for the gart.
>> 
>>> You may want to look there.
>> 
>> Ah, sorry. Indeed. Though, my idea with:
>> 
>> On Tue, Sep 10, 2013 at 5:20 AM, Alex Ivanov <gnidorah@p0n4ik.tk> wrote:
>> 
>>> Thanks! I'll try. Meanwhile i've tried a switch from page_alloc() to
>>> dma_alloc_coherent() in radeon_dummy_page_*(), which didn't help :(
>> 
>> doesn't make a sense at TTM part as well.
> 
> After the driver is loaded, you can dump some info from debugfs:
> r100_rbbm_info
> r100_cp_ring_info
> r100_cp_csq_fifo
> Which will dump a bunch of registers and internal fifos so we can see
> that the chip actually processed.
> 
> Alex

Reading of r100_cp_ring_info leads to a KP:

r100_debugfs_cp_ring_info():
count = (rdp + ring->ring_size - wdp) & ring->ptr_mask;
i = (rdp + j) & ring->ptr_mask;

        for (j = 0; j <= count; j++) {
                i = (rdp + j) & ring->ptr_mask;
		--> Here at first iteration <--
		--> count = 262080, i = 0 <--
                seq_printf(m, "r[%04d]=0x%08x\n", i, ring->ring[i]);
        }

Reading of radeon_ring_gfx (which i've additionally tried to read) 
throws an MCE:

radeon_debugfs_ring_info():
count = (ring->ring_size / 4) - ring->ring_free_dw;
i = (ring->rptr + ring->ptr_mask + 1 - 32) & ring->ptr_mask;

        for (j = 0; j <= (count + 32); j++) {
		--> Here at first iteration <--
		--> i = 262112, j = 0 <--
                seq_printf(m, "r[%5d]=0x%08x\n", i, ring->ring[i]);
                i = (i + 1) & ring->ptr_mask;
        }

I'm attaching debug outputs on kernel built with these loops commented.

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