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* framebuffer corruption due to overlapping stp instructions on arm64
@ 2018-08-02 19:31 Mikulas Patocka
       [not found] ` <CAHCPf3tFGqkYEcWNN4LaWThw_rVqT316pzLv6T7RfxwO-eZ0EA@mail.gmail.com>
  2018-08-03  7:11 ` Andrew Pinski
  0 siblings, 2 replies; 95+ messages in thread
From: Mikulas Patocka @ 2018-08-02 19:31 UTC (permalink / raw)
  To: Catalin Marinas, Will Deacon, Russell King, Thomas Petazzoni
  Cc: linux-arm-kernel, linux-kernel, libc-alpha

Hi

I tried to use a PCIe graphics card on the MacchiatoBIN board and I hit a 
strange problem.

When I use the links browser in graphics mode on the framebuffer, I get 
occasional pixel corruption. Links does memcpy, memset and 4-byte writes 
on the framebuffer - nothing else.

I found out that the pixel corruption is caused by overlapping unaligned 
stp instructions inside memcpy. In order to avoid branching, the arm64 
memcpy implementation may write the same destination twice with different 
alignment. If I put "dmb sy" between the overlapping stp instructions, the 
pixel corruption goes away.

This seems like a hardware bug. Is it a known errata? Do you have any 
workarounds for it?

I tried AMD card (HD 6350) and NVidia (NVS 285) and both exhibit the same 
corruption. OpenGL doesn't work (it results in artifacts on the AMD card 
and lock-up on the NVidia card), but it's quite expected if even simple 
writing to the framebuffer doesn't work.

Mikulas

^ permalink raw reply	[flat|nested] 95+ messages in thread

end of thread, other threads:[~2018-08-09 15:29 UTC | newest]

Thread overview: 95+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-08-02 19:31 framebuffer corruption due to overlapping stp instructions on arm64 Mikulas Patocka
     [not found] ` <CAHCPf3tFGqkYEcWNN4LaWThw_rVqT316pzLv6T7RfxwO-eZ0EA@mail.gmail.com>
2018-08-03  6:35   ` Mikulas Patocka
2018-08-03  7:16     ` Ard Biesheuvel
2018-08-03  9:41       ` Will Deacon
2018-08-03 17:09         ` Mikulas Patocka
2018-08-03 17:32           ` Sinan Kaya
2018-08-03 17:33           ` Ard Biesheuvel
2018-08-03 18:25             ` Mikulas Patocka
2018-08-03 20:44               ` Matt Sealey
2018-08-03 21:20                 ` Ard Biesheuvel
2018-08-06 10:25                   ` Mikulas Patocka
2018-08-06 12:42                     ` Robin Murphy
2018-08-06 12:53                       ` Ard Biesheuvel
2018-08-06 13:41                       ` Marcin Wojtas
2018-08-06 13:48                         ` Ard Biesheuvel
2018-08-06 14:07                           ` Marcin Wojtas
2018-08-06 14:13                             ` Mikulas Patocka
2018-08-06 15:47                       ` Ard Biesheuvel
2018-08-06 17:09                         ` Mikulas Patocka
2018-08-06 17:21                           ` Ard Biesheuvel
2018-08-06 19:54                             ` Mikulas Patocka
2018-08-06 20:11                               ` Ard Biesheuvel
2018-08-06 20:31                                 ` Mikulas Patocka
2018-08-07 16:40                                 ` Marcin Wojtas
2018-08-07 17:39                                   ` Mikulas Patocka
2018-08-07 18:07                                     ` Ard Biesheuvel
2018-08-07 18:17                                       ` Mikulas Patocka
     [not found]                                     ` <CAPv3WKcKoEe=Qysp6Oac2C=G9bUhUQf1twSRCY+_qJ6XEC-iag@mail.gmail.com>
2018-08-08 14:10                                       ` Mikulas Patocka
2018-08-06 17:13                         ` Catalin Marinas
2018-08-06 17:19                           ` Mikulas Patocka
2018-08-08 18:31                       ` Mikulas Patocka
2018-08-04 13:29                 ` Mikulas Patocka
2018-08-08 12:16                 ` Catalin Marinas
2018-08-08 13:02                   ` David Laight
2018-08-08 13:46                     ` Mikulas Patocka
2018-08-08 14:26                       ` David Laight
2018-08-08 14:50                         ` Catalin Marinas
2018-08-08 16:21                           ` Mikulas Patocka
2018-08-08 16:31                             ` Arnd Bergmann
2018-08-08 16:43                               ` David Laight
2018-08-08 18:56                                 ` Mikulas Patocka
2018-08-08 18:37                         ` Mikulas Patocka
2018-08-08 11:39           ` Catalin Marinas
2018-08-08 14:12             ` Mikulas Patocka
2018-08-08 14:28               ` Catalin Marinas
2018-08-08 18:40                 ` Mikulas Patocka
2018-08-08 15:01               ` Richard Earnshaw (lists)
2018-08-08 15:14                 ` Catalin Marinas
2018-08-08 16:01                   ` Arnd Bergmann
2018-08-08 18:25                     ` Mikulas Patocka
2018-08-08 21:51                       ` Arnd Bergmann
2018-08-09 15:29                         ` Arnd Bergmann
2018-08-03  7:11 ` Andrew Pinski
2018-08-03  7:53   ` Florian Weimer
2018-08-03  9:12     ` Szabolcs Nagy
2018-08-03  9:15     ` Ramana Radhakrishnan
2018-08-03  9:29       ` Ard Biesheuvel
2018-08-03  9:37         ` Ramana Radhakrishnan
2018-08-03  9:42         ` Richard Earnshaw (lists)
2018-08-04  0:58           ` Mikulas Patocka
2018-08-04  1:13             ` Andrew Pinski
2018-08-04 11:04               ` Mikulas Patocka
2018-08-05 18:33                 ` Florian Weimer
2018-08-06  8:02                   ` Mikulas Patocka
2018-08-06  8:10                     ` Ard Biesheuvel
2018-08-06 10:31                       ` Mikulas Patocka
2018-08-06 10:37                         ` Ard Biesheuvel
2018-08-06 10:42                           ` Mikulas Patocka
2018-08-06 10:48                             ` Ard Biesheuvel
2018-08-06 12:09                               ` Mikulas Patocka
2018-08-06 12:19                                 ` Ard Biesheuvel
2018-08-06 12:22                                   ` Ard Biesheuvel
2018-08-07 14:14                                   ` Mikulas Patocka
2018-08-07 14:40                                     ` Ard Biesheuvel
2018-08-08 19:15                                   ` Mikulas Patocka
2018-08-06 11:19                         ` Siddhesh Poyarekar
2018-08-06 11:29                           ` Ard Biesheuvel
2018-08-06 14:26                   ` Tulio Magno Quites Machado Filho
2018-08-05 21:51                 ` Pavel Machek
2018-08-06 14:30                   ` Mikulas Patocka
2018-08-03 11:24         ` David Laight
2018-08-03 12:04           ` Mikulas Patocka
2018-08-03 13:04             ` David Laight
2018-08-05 14:36               ` Mikulas Patocka
2018-08-06 10:18                 ` David Laight
2018-08-07 14:07                   ` Mikulas Patocka
2018-08-07 14:33                     ` David Laight
2018-08-08 14:21                       ` Mikulas Patocka
2018-08-03 13:20     ` Mikulas Patocka
2018-08-03 13:31   ` Mikulas Patocka
2018-08-03 14:17     ` Richard Earnshaw (lists)
2018-08-05 21:36   ` Pavel Machek
2018-08-06  8:04     ` Ramana Radhakrishnan
2018-08-06  8:44       ` Pavel Machek
2018-08-06  9:11         ` Ard Biesheuvel

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