netdev - Re: [PATCH net-next v10 1/8] hinic3: Async Event Queue interfaces

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Message-ID: <20250731140935.GE8494@horms.kernel.org>
Date: Thu, 31 Jul 2025 15:09:35 +0100
From: Simon Horman <horms@...nel.org>
To: Fan Gong <gongfan1@...wei.com>
Cc: andrew+netdev@...n.ch, christophe.jaillet@...adoo.fr, corbet@....net,
	davem@...emloft.net, edumazet@...gle.com, fuguiming@...artners.com,
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	jdamato@...tly.com, kuba@...nel.org, lee@...ger.us,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
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	netdev@...r.kernel.org, pabeni@...hat.com,
	przemyslaw.kitszel@...el.com, shenchenyang1@...ilicon.com,
	shijing34@...wei.com, sumang@...vell.com, vadim.fedorenko@...ux.dev,
	wulike1@...wei.com, zhoushuai28@...wei.com,
	zhuyikai1@...artners.com
Subject: Re: [PATCH net-next v10 1/8] hinic3: Async Event Queue interfaces

On Thu, Jul 31, 2025 at 02:39:25PM +0100, Simon Horman wrote:
> On Thu, Jul 31, 2025 at 06:49:34PM +0800, Fan Gong wrote:
> > > >
> > > > So the swapped data by HW is neither BE or LE. In this case, we should use
> > > > swab32 to obtain the correct LE data because our driver currently supports LE.
> > > > This is for compensating for bad HW decisions.
> > >
> > > Let us assume that the host is reading data provided by HW.
> > >
> > > If the swab32 approach works on a little endian host
> > > to allow the host to access 32-bit values in host byte order.
> > > Then this is because it outputs a 32-bit little endian values.
> > >
> > > But, given the same input, it will not work on a big endian host.
> > > This is because the same little endian output will be produced,
> > > while the host byte order is big endian.
> > >
> > > I think you need something based on be32_to_cpu()/cpu_to_be32().
> > > This will effectively be swab32 on little endian hosts (no change!).
> > > And a no-op on big endian hosts (addressing my point above).
> > >
> > > More specifically, I think you should use be32_to_cpu_array() and
> > > cpu_to_be32_array() instead of swab32_array().
> > 
> > Thanks. We'll take your suggestion.
> 
> Thanks, I really appreciate that.

Sorry, I missed Gur's related email before responding.
It seems that conversation now supersedes this one.

[1]https://lore.kernel.org/netdev/20250731125839.1137083-1-gur.stavi@huawei.com/