Hi Christoph,
Am 09.01.20 um 15:14 schrieb Christoph Hellwig:
Hi Woody,
sorry for the late reply, I've been off to a vacation over the holidays.
On Sat, Dec 14, 2019 at 10:17:15PM -0500, Woody Suwalski wrote:
Regression in 5.4 kernel on 32-bit Radeon IBM T40 triggered by commit 33b3ad3788aba846fc8b9a065fe2685a0b64f713 Author: Christoph Hellwig hch@lst.de Date: Thu Aug 15 09:27:00 2019 +0200
Howdy, The above patch has triggered a display problem on IBM Thinkpad T40, where the screen is covered with a lots of random short black horizontal lines, or distorted letters in X terms.
The culprit seems to be that the dma_get_required_mask() is returning a value 0x3fffffff which is smaller than dma_get_mask()0xffffffff.That results in dma_addressing_limited()==0 in ttm_bo_device(), and using 40-bits dma instead of 32-bits.
Which is the intended behavior assuming your system has 1GB of memory. Does it?
Assuming the system doesn't have the 1GB split up somehow crazy over the address space that should indeed work as intended.
If I hardcode "1" as the last parameter to ttm_bo_device_init() in place of a call to dma_addressing_limited(),the problem goes away.
I'll need some help from the drm / radeon / TTM maintainers if there are any other side effects from not passing the need_dma32 paramters. Obviously if the device doesn't have more than 32-bits worth of dram and no DMA offset we can't feed unaddressable memory to the device. Unfortunately I have a very hard time following the implementation of the TTM pool if it does anything else in this case.
The only other thing which comes to mind is using huge pages. Can you try a kernel with CONFIG_TRANSPARENT_HUGEPAGE disabled?
Thanks, Christian.
Christian König wrote:
Hi Christoph,
Am 09.01.20 um 15:14 schrieb Christoph Hellwig:
Hi Woody,
sorry for the late reply, I've been off to a vacation over the holidays.
On Sat, Dec 14, 2019 at 10:17:15PM -0500, Woody Suwalski wrote:
Regression in 5.4 kernel on 32-bit Radeon IBM T40 triggered by commit 33b3ad3788aba846fc8b9a065fe2685a0b64f713 Author: Christoph Hellwig hch@lst.de Date: Thu Aug 15 09:27:00 2019 +0200
Howdy, The above patch has triggered a display problem on IBM Thinkpad T40, where the screen is covered with a lots of random short black horizontal lines, or distorted letters in X terms.
The culprit seems to be that the dma_get_required_mask() is returning a value 0x3fffffff which is smaller than dma_get_mask()0xffffffff.That results in dma_addressing_limited()==0 in ttm_bo_device(), and using 40-bits dma instead of 32-bits.
Which is the intended behavior assuming your system has 1GB of memory. Does it?
Assuming the system doesn't have the 1GB split up somehow crazy over the address space that should indeed work as intended.
If I hardcode "1" as the last parameter to ttm_bo_device_init() in place of a call to dma_addressing_limited(),the problem goes away.
I'll need some help from the drm / radeon / TTM maintainers if there are any other side effects from not passing the need_dma32 paramters. Obviously if the device doesn't have more than 32-bits worth of dram and no DMA offset we can't feed unaddressable memory to the device. Unfortunately I have a very hard time following the implementation of the TTM pool if it does anything else in this case.
The only other thing which comes to mind is using huge pages. Can you try a kernel with CONFIG_TRANSPARENT_HUGEPAGE disabled?
Thanks, Christian.
Happy New Year :-)
Yes, the box has 1G of RAM, and unfortunately nope, TRANSPARENT_HUGEPAGE is not on. I am attaching the .config, maybe you can find some insanity there... Also - for reference - a minimalistic patch fixing symptoms (but not addressing the root cause :-( )
I can try to rebuild the kernel with HIGHMEM off, although I am not optimistic it will change anything. But at least it should simplify the 1G split...
So if you have any other ideas - pls let me know..
Thanks, Woody
Woody Suwalski wrote:
Christian König wrote:
Hi Christoph,
Am 09.01.20 um 15:14 schrieb Christoph Hellwig:
Hi Woody,
sorry for the late reply, I've been off to a vacation over the holidays.
On Sat, Dec 14, 2019 at 10:17:15PM -0500, Woody Suwalski wrote:
Regression in 5.4 kernel on 32-bit Radeon IBM T40 triggered by commit 33b3ad3788aba846fc8b9a065fe2685a0b64f713 Author: Christoph Hellwig hch@lst.de Date: Thu Aug 15 09:27:00 2019 +0200
Howdy, The above patch has triggered a display problem on IBM Thinkpad T40, where the screen is covered with a lots of random short black horizontal lines, or distorted letters in X terms.
The culprit seems to be that the dma_get_required_mask() is returning a value 0x3fffffff which is smaller than dma_get_mask()0xffffffff.That results in dma_addressing_limited()==0 in ttm_bo_device(), and using 40-bits dma instead of 32-bits.
Which is the intended behavior assuming your system has 1GB of memory. Does it?
Assuming the system doesn't have the 1GB split up somehow crazy over the address space that should indeed work as intended.
If I hardcode "1" as the last parameter to ttm_bo_device_init() in place of a call to dma_addressing_limited(),the problem goes away.
I'll need some help from the drm / radeon / TTM maintainers if there are any other side effects from not passing the need_dma32 paramters. Obviously if the device doesn't have more than 32-bits worth of dram and no DMA offset we can't feed unaddressable memory to the device. Unfortunately I have a very hard time following the implementation of the TTM pool if it does anything else in this case.
The only other thing which comes to mind is using huge pages. Can you try a kernel with CONFIG_TRANSPARENT_HUGEPAGE disabled?
Thanks, Christian.
Happy New Year :-)
Yes, the box has 1G of RAM, and unfortunately nope, TRANSPARENT_HUGEPAGE is not on. I am attaching the .config, maybe you can find some insanity there... Also - for reference - a minimalistic patch fixing symptoms (but not addressing the root cause :-( )
I can try to rebuild the kernel with HIGHMEM off, although I am not optimistic it will change anything. But at least it should simplify the 1G split...
So if you have any other ideas - pls let me know..
Thanks, Woody
Interesting. Rebuilding the kernel with HIMEM disabled actually solves the display problem. The debug lines show exactly same values for dma_get_required_mask() and dma_get_mask(), yet now it works OK... So what has solved it???
Woody
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Den 09-01-2020 kl. 17:12, skrev Christian König:
Hi Christoph,
Am 09.01.20 um 15:14 schrieb Christoph Hellwig:
Hi Woody,
sorry for the late reply, I've been off to a vacation over the holidays.
On Sat, Dec 14, 2019 at 10:17:15PM -0500, Woody Suwalski wrote:
Regression in 5.4 kernel on 32-bit Radeon IBM T40 triggered by commit 33b3ad3788aba846fc8b9a065fe2685a0b64f713 Author: Christoph Hellwig hch@lst.de Date: Thu Aug 15 09:27:00 2019 +0200
Howdy, The above patch has triggered a display problem on IBM Thinkpad T40, where the screen is covered with a lots of random short black horizontal lines, or distorted letters in X terms.
The culprit seems to be that the dma_get_required_mask() is returning a value 0x3fffffff which is smaller than dma_get_mask()0xffffffff.That results in dma_addressing_limited()==0 in ttm_bo_device(), and using 40-bits dma instead of 32-bits.
Which is the intended behavior assuming your system has 1GB of memory. Does it?
Assuming the system doesn't have the 1GB split up somehow crazy over the address space that should indeed work as intended.
If I hardcode "1" as the last parameter to ttm_bo_device_init() in place of a call to dma_addressing_limited(),the problem goes away.
I'll need some help from the drm / radeon / TTM maintainers if there are any other side effects from not passing the need_dma32 paramters. Obviously if the device doesn't have more than 32-bits worth of dram and no DMA offset we can't feed unaddressable memory to the device. Unfortunately I have a very hard time following the implementation of the TTM pool if it does anything else in this case.
The only other thing which comes to mind is using huge pages. Can you try a kernel with CONFIG_TRANSPARENT_HUGEPAGE disabled?
Any progress on this ?
We have a bugreport in Mageia with the hw: Dell Inspiron 5100, 32-bit P4 processor, 2GB of RAM, Radeon Mobility 7500 (RV200) graphics
that gets display issues too and reverting the offending commit restores normal behaviour.
and the same issue is still there with 5.5 series kernels.
-- Thomas
On Mon, Feb 24, 2020 at 4:20 AM Thomas Backlund tmb@mageia.org wrote:
Den 09-01-2020 kl. 17:12, skrev Christian König:
Hi Christoph,
Am 09.01.20 um 15:14 schrieb Christoph Hellwig:
Hi Woody,
sorry for the late reply, I've been off to a vacation over the holidays.
On Sat, Dec 14, 2019 at 10:17:15PM -0500, Woody Suwalski wrote:
Regression in 5.4 kernel on 32-bit Radeon IBM T40 triggered by commit 33b3ad3788aba846fc8b9a065fe2685a0b64f713 Author: Christoph Hellwig hch@lst.de Date: Thu Aug 15 09:27:00 2019 +0200
Howdy, The above patch has triggered a display problem on IBM Thinkpad T40, where the screen is covered with a lots of random short black horizontal lines, or distorted letters in X terms.
The culprit seems to be that the dma_get_required_mask() is returning a value 0x3fffffff which is smaller than dma_get_mask()0xffffffff.That results in dma_addressing_limited()==0 in ttm_bo_device(), and using 40-bits dma instead of 32-bits.
Which is the intended behavior assuming your system has 1GB of memory. Does it?
Assuming the system doesn't have the 1GB split up somehow crazy over the address space that should indeed work as intended.
If I hardcode "1" as the last parameter to ttm_bo_device_init() in place of a call to dma_addressing_limited(),the problem goes away.
I'll need some help from the drm / radeon / TTM maintainers if there are any other side effects from not passing the need_dma32 paramters. Obviously if the device doesn't have more than 32-bits worth of dram and no DMA offset we can't feed unaddressable memory to the device. Unfortunately I have a very hard time following the implementation of the TTM pool if it does anything else in this case.
The only other thing which comes to mind is using huge pages. Can you try a kernel with CONFIG_TRANSPARENT_HUGEPAGE disabled?
Any progress on this ?
We have a bugreport in Mageia with the hw: Dell Inspiron 5100, 32-bit P4 processor, 2GB of RAM, Radeon Mobility 7500 (RV200) graphics
that gets display issues too and reverting the offending commit restores normal behaviour.
and the same issue is still there with 5.5 series kernels.
Does disabling HIMEM or setting radeon.agpmode=-1 on the kernel command line in grub fix the issue?
Alex
dri-devel@lists.freedesktop.org
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Alex Deucher -
Christian König -
Thomas Backlund -
Thomas Schwinge -
Woody Suwalski