linux-kernel - Re: [PATCH v2] bus: mhi: host: don't free bhie tables during suspend/hibernation

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Message-ID: <h2wv7drxntokziiwbzjw5xjzbctbomp6cfcba7ppfbih6o7so7@p6dazv32xfx4>
Date: Fri, 25 Apr 2025 12:34:10 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Muhammad Usama Anjum <usama.anjum@...labora.com>
Cc: Johannes Berg <johannes@...solutions.net>, 
	Jeff Johnson <jjohnson@...nel.org>, Jeffrey Hugo <quic_jhugo@...cinc.com>, 
	Yan Zhen <yanzhen@...o.com>, Youssef Samir <quic_yabdulra@...cinc.com>, 
	Qiang Yu <quic_qianyu@...cinc.com>, Alex Elder <elder@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Kunwu Chan <chentao@...inos.cn>, kernel@...labora.com, 
	mhi@...ts.linux.dev, linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-wireless@...r.kernel.org, ath11k@...ts.infradead.org
Subject: Re: [PATCH v2] bus: mhi: host: don't free bhie tables during
 suspend/hibernation

On Thu, Apr 10, 2025 at 07:56:54PM +0500, Muhammad Usama Anjum wrote:
> Fix dma_direct_alloc() failure at resume time during bhie_table
> allocation. There is a crash report where at resume time, the memory
> from the dma doesn't get allocated and MHI fails to re-initialize.
> There may be fragmentation of some kind which fails the allocation
> call.
> 

If dma_direct_alloc() fails, then it is a platform limitation/issue. We cannot
workaround that in the device drivers. What is the guarantee that other drivers
will also continue to work? Will you go ahead and patch all of them which
release memory during suspend?

Please investigate why the allocation fails. Even this is not a device issue, so
we cannot add quirks :/

> To fix it, don't free the memory at power down during suspend /
> hibernation. Instead, use the same allocated memory again after every
> resume / hibernation. This patch has been tested with resume and
> hibernation both.
> 
> The rddm is of constant size for a given hardware. While the fbc_image
> size depends on the firmware. If the firmware changes, we'll free and
> allocate new memory for it.
> 
> Here are the crash logs:
> 
> [ 3029.338587] mhi mhi0: Requested to power ON
> [ 3029.338621] mhi mhi0: Power on setup success
> [ 3029.668654] kworker/u33:8: page allocation failure: order:7, mode:0xc04(GFP_NOIO|GFP_DMA32), nodemask=(null),cpuset=/,mems_allowed=0
> [ 3029.668682] CPU: 4 UID: 0 PID: 2744 Comm: kworker/u33:8 Not tainted 6.11.11-valve10-1-neptune-611-gb69e902b4338 #1ed779c892334112fb968aaa3facf9686b5ff0bd7
> [ 3029.668690] Hardware name: Valve Galileo/Galileo, BIOS F7G0112 08/01/2024

Did you intend to leak this information? If not, please remove it from
stacktrace.

- Mani

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