linux-kernel - Re: [PATCH 09/18] serial: sc16is7xx: add macro for max number of UART ports

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Date: Thu, 21 Dec 2023 12:00:58 -0500
From: Hugo Villeneuve <hugo@...ovil.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: gregkh@...uxfoundation.org, jirislaby@...nel.org, jringle@...dpoint.com,
 kubakici@...pl, phil@...pberrypi.org, linux-kernel@...r.kernel.org,
 linux-serial@...r.kernel.org, Hugo Villeneuve <hvilleneuve@...onoff.com>
Subject: Re: [PATCH 09/18] serial: sc16is7xx: add macro for max number of
 UART ports

On Thu, 21 Dec 2023 18:55:17 +0200
Andy Shevchenko <andriy.shevchenko@...el.com> wrote:

> On Thu, Dec 21, 2023 at 11:41:03AM -0500, Hugo Villeneuve wrote:
> > On Wed, 20 Dec 2023 17:50:34 +0200
> > Andy Shevchenko <andriy.shevchenko@...el.com> wrote:
> > > On Tue, Dec 19, 2023 at 12:18:53PM -0500, Hugo Villeneuve wrote:
> 
> ...
> 
> > > > -	if (count < 0 || count > ARRAY_SIZE(irda_port))
> > > > +	if (count < 0 || count > SC16IS7XX_MAX_PORTS)
> > > 
> > > ARRAY_SIZE() is more robust than this. What if you change to support different
> > > devices where this won't be as defined?
> > 
> > not sure that I understand your point, because SC16IS7XX_MAX_PORTS is
> > the maximum for all devices supported by this driver. The irda_port
> > array always has a fixed number of elements set to SC16IS7XX_MAX_PORTS,
> > even if the device that we are probing has only one port for example.
> 
> For current models of the device, yes. Who knows the future?
> Also, ARRAY_SIZE() make it less points to update if ever needed.
> 
> > But I can change it back to ARRAY_SIZE(irda_port) if you want.
> 
> Please change it back.
> 
> > > >  		return;
> 
> ...
> 
> > > > +	WARN_ON(devtype->nr_uart > SC16IS7XX_MAX_PORTS);
> > > 
> > > Not sure about this, perhaps it's fine.
> > 
> > This check is only there if we add support for a new device and we
> > incorrectly set nr_uart to an incorrect value, which will cause other
> > problems anyway, of course :)
> > 
> > This could be removed.
> 
> Let's remove. We can add it back in case something like this (quite unlikely)
> happens.

Ok, will do both for v2.

Hugo Villeneuve