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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: David Binderman <dcb314@hotmail.com>
Cc: "andrzej.hajda@intel.com" <andrzej.hajda@intel.com>,
	"neil.armstrong@linaro.org" <neil.armstrong@linaro.org>,
	"rfoss@kernel.org" <rfoss@kernel.org>,
	"jonas@kwiboo.se" <jonas@kwiboo.se>,
	"jernej.skrabec@gmail.com" <jernej.skrabec@gmail.com>,
	"airlied@gmail.com" <airlied@gmail.com>,
	"daniel@ffwll.ch" <daniel@ffwll.ch>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: drivers/gpu/drm/bridge/fsl-ldb.c:101: possible loss of information.
Date: Thu, 9 Mar 2023 11:26:47 +0200	[thread overview]
Message-ID: <20230309092647.GM31765@pendragon.ideasonboard.com> (raw)
In-Reply-To: <DB6P189MB056810B266B656706ECF7EAB9CB59@DB6P189MB0568.EURP189.PROD.OUTLOOK.COM>

Hi David,

On Thu, Mar 09, 2023 at 07:59:34AM +0000, David Binderman wrote:
> Hello there Laurent,
> 
> >We could, but I don't think it will make any difference in practice as
> >the maximum pixel clock frequency supported by the SoC is 80MHz (per
> >LVDS channel). That would result in a 560MHz frequency returned by this
> >function, well below the 31 bits limit.
> 
> Thanks for your explanation. I have a couple of suggestions for possible improvements:
> 
> 1. Your explanatory text in a comment nearby. This helps all readers of the code.
> 
> 2. Might the frequency go up to 300 MHz anytime soon ? The code will stop working then. 
> In this case, I would suggest to put in a run time sanity check to make sure no 31 bit overflow. 

As it's a hardware limit of the SoC, I wouldn't expect so.

This being said, I think adding a UL suffix to the constants would be
better than a comment as it will please static checkers and serve as
documentation to humans. Would you be able to send a patch to fix this ?

> Just a couple of ideas for the code.

Thanks for taking the time to share those.

-- 
Regards,

Laurent Pinchart

  reply	other threads:[~2023-03-09  9:26 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-07 16:45 David Binderman
2023-03-08 23:22 ` Laurent Pinchart
2023-03-09  7:59   ` David Binderman
2023-03-09  9:26     ` Laurent Pinchart [this message]
2023-03-09  9:42       ` David Binderman
2023-03-09 10:04         ` Laurent Pinchart

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