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

[Alex Ivanov]

21.09.2013, в 1:27, Alex Deucher <alexdeucher at gmail.com> написал(а):

> On Tue, Sep 17, 2013 at 3:33 PM, Alex Ivanov <gnidorah at p0n4ik.tk> wrote:
>> 17.09.2013, в 18:24, Alex Deucher <alexdeucher at gmail.com> написал(а):
>> 
>>> On Tue, Sep 17, 2013 at 5:23 AM, Alex Ivanov <gnidorah at p0n4ik.tk> wrote:
>>>> Alex,
>>>> 
>>>> 10.09.2013, в 16:37, Alex Deucher <alexdeucher at 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 at 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.
> 
> The register writes seems to be going through the register backbone correctly:
> 
> [0x00B] 0x15E0=0x00000000
> [0x00C] 0x15E4=0xCAFEDEAD
> [0x00D] 0x4274=0x0000000F
> [0x00E] 0x42C8=0x00000007
> [0x00F] 0x4018=0x0000001D
> [0x010] 0x170C=0x80000000
> [0x011] 0x3428=0x00020100
> [0x012] 0x15E4=0xCAFEDEAD
> 
> You can see the 0xCAFEDEAD written to the scratch register via MMIO
> from the ring_test(). The CP fifo however seems to be full of garbage.
> The CP is busy though, so it seems to be functional.  I guess it's
> just fetching garbage rather than commands.
> 
> Does doing a posted write when writing to the ring buffer help?

Unfortunately, no.

> 
> diff --git a/drivers/gpu/drm/radeon/radeon_ring.c
> b/drivers/gpu/drm/radeon/radeon_ring.c
> index a890756..b4f04d2 100644
> --- a/drivers/gpu/drm/radeon/radeon_ring.c
> +++ b/drivers/gpu/drm/radeon/radeon_ring.c
> @@ -324,12 +324,14 @@ static int radeon_debugfs_ring_init(struct
> radeon_device *rdev, struct radeon_ri
>  */
> void radeon_ring_write(struct radeon_ring *ring, uint32_t v)
> {
> +       u32 tmp;
> #if DRM_DEBUG_CODE
>        if (ring->count_dw <= 0) {
>                DRM_ERROR("radeon: writing more dwords to the ring
> than expected!\n");
>        }
> #endif
>        ring->ring[ring->wptr++] = v;
> +       tmp = ring->ring[ring->wptr - 1];
>        ring->wptr &= ring->ptr_mask;
>        ring->count_dw--;
>        ring->ring_free_dw--;