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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: Will Deacon <will.deacon@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	linux-pci@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
	Mark Brown <mark.brown@linaro.org>
Subject: Re: [PATCH] PCI: generic: map config window in one go
Date: Fri, 29 Jan 2016 15:32:01 +0100	[thread overview]
Message-ID: <CAKv+Gu_V83bUktPX0EiHd6qCDT2y0NEx=4n-uVv=P2MF9AZbMQ@mail.gmail.com> (raw)
In-Reply-To: <20160129142831.GF4541@arm.com>

On 29 January 2016 at 15:28, Will Deacon <will.deacon@arm.com> wrote:
> Hi Ard,
>
> On Fri, Jan 29, 2016 at 03:17:15PM +0100, Ard Biesheuvel wrote:
>> Instead of iterating over the PCI config window and performing individual
>> ioremap() calls on all the adjacent slices, perform a single ioremap() to
>> map the entire region, and divvy it up later. This not only prevents
>> leaving some of it mapped if we fail half way through, it also ensures that
>> archs that support huge-vmap can use section mappings to perform the
>> mapping.
>>
>> On my Seattle A0 box, this transforms 128 separate 1 MB mappings that are
>> mapped down to 4 KB pages into a single 128 MB mapping using 2 MB sections,
>> saving 512 KB worth of page tables.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>
> The code was written this way in response to feedback during driver review
> that we couldn't necessarily grab that much contiguous vmalloc space on
> 32-bit ARM. Unless that's changed, we probably want to to predicate this
> change on having a 64-bit arch.
>

Ah right. How about testing for the ARCH_HAVE_HUGE_VMAP Kconfig symbol
explicitly?

WARNING: multiple messages have this Message-ID (diff)
From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] PCI: generic: map config window in one go
Date: Fri, 29 Jan 2016 15:32:01 +0100	[thread overview]
Message-ID: <CAKv+Gu_V83bUktPX0EiHd6qCDT2y0NEx=4n-uVv=P2MF9AZbMQ@mail.gmail.com> (raw)
In-Reply-To: <20160129142831.GF4541@arm.com>

On 29 January 2016 at 15:28, Will Deacon <will.deacon@arm.com> wrote:
> Hi Ard,
>
> On Fri, Jan 29, 2016 at 03:17:15PM +0100, Ard Biesheuvel wrote:
>> Instead of iterating over the PCI config window and performing individual
>> ioremap() calls on all the adjacent slices, perform a single ioremap() to
>> map the entire region, and divvy it up later. This not only prevents
>> leaving some of it mapped if we fail half way through, it also ensures that
>> archs that support huge-vmap can use section mappings to perform the
>> mapping.
>>
>> On my Seattle A0 box, this transforms 128 separate 1 MB mappings that are
>> mapped down to 4 KB pages into a single 128 MB mapping using 2 MB sections,
>> saving 512 KB worth of page tables.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>
> The code was written this way in response to feedback during driver review
> that we couldn't necessarily grab that much contiguous vmalloc space on
> 32-bit ARM. Unless that's changed, we probably want to to predicate this
> change on having a 64-bit arch.
>

Ah right. How about testing for the ARCH_HAVE_HUGE_VMAP Kconfig symbol
explicitly?

  reply	other threads:[~2016-01-29 14:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-29 14:17 [PATCH] PCI: generic: map config window in one go Ard Biesheuvel
2016-01-29 14:17 ` Ard Biesheuvel
2016-01-29 14:19 ` Ard Biesheuvel
2016-01-29 14:19   ` Ard Biesheuvel
2016-01-29 14:22   ` Ard Biesheuvel
2016-01-29 14:22     ` Ard Biesheuvel
2016-01-29 14:28 ` Will Deacon
2016-01-29 14:28   ` Will Deacon
2016-01-29 14:32   ` Ard Biesheuvel [this message]
2016-01-29 14:32     ` Ard Biesheuvel
2016-01-29 14:52     ` Arnd Bergmann
2016-01-29 14:52       ` Arnd Bergmann
2016-02-05 10:48       ` Ard Biesheuvel
2016-02-05 10:48         ` Ard Biesheuvel
2016-02-05 13:37         ` Arnd Bergmann
2016-02-05 13:37           ` Arnd Bergmann
2016-02-05 14:09           ` Ard Biesheuvel
2016-02-05 14:09             ` Ard Biesheuvel

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