linux-kernel - Re: [PATCH] net: ethernet: Use dma_set_mask_and

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Message-ID: <f3a7d89c-43b4-4d5a-ac70-6b14c77b4cd4@lunn.ch>
Date: Mon, 25 Nov 2024 19:10:08 +0100
From: Andrew Lunn <andrew@...n.ch>
To: zhangheng <zhangheng@...inos.cn>
Cc: joyce.ooi@...el.com, andrew+netdev@...n.ch, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	chris.snook@...il.com, f.fainelli@...il.com, horms@...nel.org,
	shannon.nelson@....com, jacob.e.keller@...el.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: ethernet: Use dma_set_mask_and_coherent to set DMA
 mask

On Mon, Nov 25, 2024 at 11:34:46AM +0800, zhangheng wrote:
> Many drivers still have two explicit calls of dma_set_mask() and
> dma_set_coherent_mask().
> 
> Let's simplify with dma_set_mask_and_coherent().

Is simplification a sufficient justification?

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html#clean-up-patches

1.6.6. Clean-up patches

  Netdev discourages patches which perform simple clean-ups, which are
  not in the context of other work. For example:

  Addressing checkpatch.pl warnings

  Addressing Local variable ordering issues

  Conversions to device-managed APIs (devm_ helpers)

  This is because it is felt that the churn that such changes produce
  comes at a greater cost than the value of such clean-ups.

What is the value of this simplification? What is the likelihood you
have actually broken something? The problem with these sorts of
patches is that they are often made blindly without understanding the
code and a small percentage actually break things. As a result,
Maintainers need to look at these patches and spend the time to
actually understand them. I would prefer to spend that time on new
drivers, rather than old code which works and does not really benefit
from simplification.

	Andrew