From: sricharan@codeaurora.org (Sricharan)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH V2 1/2] drivers: i2c: qup: Fix broken dma when CONFIG_DEBUG_SG is enabled
Date: Mon, 16 May 2016 10:49:04 +0530 [thread overview]
Message-ID: <000e01d1af32$7c05de40$74119ac0$@codeaurora.org> (raw)
In-Reply-To: <20160513114716.GI1778@katana>
Hi,
> > With CONFIG_DEBUG_SG is enabled and when dma mode is used, below
> dump
> > is seen,
> >
> > ------------[ cut here ]------------
> > kernel BUG at include/linux/scatterlist.h:140!
> > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP Modules linked in:
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.4.0-00459-g9f087b9-dirty
> > #7 Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
> > task: ffffffc036868000 ti: ffffffc036870000 task.ti: ffffffc036870000
> > PC is at qup_sg_set_buf.isra.13+0x138/0x154
> > LR is at qup_sg_set_buf.isra.13+0x50/0x154 pc : [<ffffffc0005a0ed8>]
> > lr : [<ffffffc0005a0df0>] pstate: 60000145 sp : ffffffc0368735c0
> > x29: ffffffc0368735c0 x28: ffffffc036873752
> > x27: ffffffc035233018 x26: ffffffc000c4e000
> > x25: 0000000000000000 x24: 0000000000000004
> > x23: 0000000000000000 x22: ffffffc035233668
> > x21: ffffff80004e3000 x20: ffffffc0352e0018
> > x19: 0000004000000000 x18: 0000000000000028
> > x17: 0000000000000004 x16: ffffffc0017a39c8
> > x15: 0000000000001cdf x14: ffffffc0019929d8
> > x13: ffffffc0352e0018 x12: 0000000000000000
> > x11: 0000000000000001 x10: 0000000000000001
> > x9 : ffffffc0012b2d70 x8 : ffffff80004e3000
> > x7 : 0000000000000018 x6 : 0000000030000000
> > x5 : ffffffc00199f018 x4 : ffffffc035233018
> > x3 : 0000000000000004 x2 : 00000000c0000000
> > x1 : 0000000000000003 x0 : 0000000000000000
> >
> > Process swapper/0 (pid: 1, stack limit = 0xffffffc036870020)
> > Stack: (0xffffffc0368735c0 to 0xffffffc036874000)
> >
> > Change allocation of sg buffers from dma_coherent memory to kzalloc to
> > fix the issue.
>
> This description describes what you do. But not why it is the correct
solution
> to the OOPS. The OOPS neither describes it. Please add some more
> explanation.
>
Ok,will describe it more. The reason it oops is sg_set_bug expects that
the
buf parameter passed in should be a from the lowmem and a valid
pageframe.
This is not true for pages from dma_alloc_coherent which can be carveouts,
hence
the check fails. Allocating buffers using kzalloc fixes the issue.
Regards,
Sricharan
next prev parent reply other threads:[~2016-05-16 5:19 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-06 11:31 [PATCH V2 0/2] drivers: i2c: qup: Some misc fixes Sricharan R
2016-05-06 11:31 ` [PATCH V2 1/2] drivers: i2c: qup: Fix broken dma when CONFIG_DEBUG_SG is enabled Sricharan R
2016-05-06 17:36 ` [V2, " Naveen Kaje
2016-05-13 11:47 ` [PATCH V2 " Wolfram Sang
2016-05-16 5:19 ` Sricharan [this message]
2016-05-06 11:31 ` [PATCH V2 2/2] drivers: i2c: qup: Fix error handling Sricharan R
2016-05-06 17:53 ` [V2,2/2] " Naveen Kaje
2016-05-13 11:48 ` [PATCH V2 2/2] " Wolfram Sang
2016-05-13 11:50 ` Wolfram Sang
2016-05-16 5:59 ` Sricharan
2016-05-13 11:44 ` [PATCH V2 0/2] drivers: i2c: qup: Some misc fixes Wolfram Sang
2016-05-16 5:13 ` Sricharan
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