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From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: David Brownell <david-b@pacbell.net>,
	linux-ide@vger.kernel.org,
	Kevin Hilman <khilman@deeprootsystems.com>
Subject: Re: [patch 2.6.29-rc2] palm_bk3710 buildfix
Date: Mon, 19 Jan 2009 16:06:47 +0300	[thread overview]
Message-ID: <49747AE7.7060908@ru.mvista.com> (raw)
In-Reply-To: <200901191307.33405.bzolnier@gmail.com>

Bartlomiej Zolnierkiewicz wrote:

>>>>>>Someone should fix hw_regs_t to neither be a typedef, nor
>>>>>>use "unsigned long" where it should use "void __iomem *".

>>>>>    It cannot use pointers of course -- as the addresses can be I/O 
>>>>>ports.

>>>>It could use the ioread*() calls, which take pointers
>>>>and handle both types of I/O in a type-safe manner.

>>>  Probably they can... though using those would only slow down 
>>>register access on x86.

>>   ... and cause code bloat due to switching to real function calls from 
>>inlines which now should render into in/out isns.

> OTOH it would allow to unify a lot of 'if (hwif->host_flags & IDE_HFLAG_MMIO)'
> cases so the code may even shrink.

    It won't shrink as much as it will grow.

> I also suspect that register access slow
> down is most likely negligable (we can always measure and check it).

    I'd agree here but code bloat won't be as negligible considering the IDE 
code's predominant use of I/O ports on x86.

> The real reason for not using ioread*() and co. is that not all archs support
> them (though I checked some time ago, maybe they do now?) and we don't want to
> break IDE support for them.

    Sure. :-)

> Thanks,
> Bart

MBR, Sergei

  reply	other threads:[~2009-01-19 13:06 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-18 16:33 [patch 2.6.29-rc2] palm_bk3710 buildfix David Brownell
2009-01-18 17:14 ` Sergei Shtylyov
2009-01-19  0:29   ` David Brownell
2009-01-19  8:35     ` Sergei Shtylyov
2009-01-19  8:57       ` Sergei Shtylyov
2009-01-19 12:07         ` Bartlomiej Zolnierkiewicz
2009-01-19 13:06           ` Sergei Shtylyov [this message]
2009-01-19 14:14             ` Sergei Shtylyov
2009-01-19 12:00   ` Bartlomiej Zolnierkiewicz
2009-01-19 13:03     ` Sergei Shtylyov
2009-01-19 13:21       ` Bartlomiej Zolnierkiewicz

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