Messages in this thread | | | Subject | Re: Regression in 5.4 kernel on 32-bit Radeon IBM T40 | From | Meelis Roos <> | Date | Sun, 15 Dec 2019 18:04:09 +0200 |
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15.12.19 05:17 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.
I have the same problem on 32-bit Dell Latitude D600.
> 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.
Tried this on top on 5.4.0 and it helped here too.
-- Meelis Roos <mroos@linux.ee>
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