From: Meelis Roos <mroos@linux.ee>
To: Woody Suwalski <terraluna977@gmail.com>
Cc: "Christian König" <christian.koenig@amd.com>,
"Deucher, Alexander" <alexander.deucher@amd.com>,
linux-kernel@vger.kernel.org, "Pavel Machek" <pavel@ucw.cz>
Subject: Re: Regression in 5.4 kernel on 32-bit Radeon IBM T40
Date: Sun, 15 Dec 2019 18:04:09 +0200 [thread overview]
Message-ID: <1e6a6ccb-a7a0-4173-d667-a53eb99b8699@linux.ee> (raw)
In-Reply-To: <400f6ce9-e360-0860-ca2a-fb8bccdcdc9b@gmail.com>
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>
next prev parent reply other threads:[~2019-12-15 16:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-15 3:17 Regression in 5.4 kernel on 32-bit Radeon IBM T40 Woody Suwalski
2019-12-15 16:04 ` Meelis Roos [this message]
2020-01-09 14:14 ` Christoph Hellwig
2020-01-09 15:12 ` Christian König
2020-01-09 22:40 ` Woody Suwalski
2020-01-10 2:40 ` Woody Suwalski
2020-03-14 22:06 ` Thomas Schwinge
2020-02-22 16:16 ` Thomas Backlund
2020-09-16 22:15 ` Alex Deucher
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