netdev - Re: [PATCH 1/2] 8139too: Make PIO/MMIO a modparam

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Message-ID: <487D2AEE.8030309@garzik.org>
Date:	Tue, 15 Jul 2008 18:55:42 -0400
From:	Jeff Garzik <jeff@...zik.org>
To:	Dave Jones <davej@...hat.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>, netdev@...r.kernel.org
Subject: Re: [PATCH 1/2] 8139too: Make PIO/MMIO a modparam

Dave Jones wrote:
> On Tue, Jul 15, 2008 at 06:18:30PM -0400, Jeff Garzik wrote:
>  
>  > > Make PIO/MMIO a runtime thing via a module parameter.
>  > > This is needed to support devices that only work with PIO
>  > > without penalising devices that work fine with MMIO in
>  > > distro kernels.
>  > > 
>  > > Signed-off-by: Dave Jones <davej@...hat.com>
>  > 
>  > Looks great overall.
>  > 
>  > Minor nits:
>  > 
>  > * need module param text description
> 
> oops. will fix.
>  
>  > * [optional] if code not too ugly, change mod param description based on 
>  > CONFIG_8139TOO_PIO to indicate the currently compiled default
> 
> Not sure of a non-icky way to do this other than ifdefs.
> The best I could come up with is.
> 
> #ifdef CONFIG_8139TOO_PIO
> MODULE_PARM_DESC(use_io, "PIO/MMIO switch.  0=MMIO 1=PIO default=PIO"); 
> #else
> MODULE_PARM_DESC(use_io, "PIO/MMIO switch.  0=MMIO 1=PIO default=MMIO"); 
> #endif
> 
> palatable?

best you can do AFAIK, so yes


>  > * [optional] would prefer CONFIG_8139TOO_PIO be handled at compile time, 
>  > by changing the initialized value
> 
> This bit should be taken care of in rtl8139_init_module() at the bottom..
> 
> +       /* enable PIO instead of MMIO, if CONFIG_8139TOO_PIO is selected */
> +#ifdef CONFIG_8139TOO_PIO
> +       use_io = 1;
> +#endif

Right, I was saying I prefer simply to set the initialized value 
appropriately, and avoid the extra code dollup during module load.


>  > * [extra project] would be highly useful for MMIO to fall back to PIO, 
>  > and vice versa, should any resource be unavailable.  Sometimes, mainly 
>  > with MMIO and broken/weird BIOSen, only the PIO PCI BARs will be filled 
>  > in with useful info.
> 
> Sounds do-able. I'll add it to my rainy-day project list.

Thanks :)  A few users out in the wild will definitely thank you.

	Jeff



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