From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Russell King <rmk@arm.linux.org.uk>, linux-arch@vger.kernel.org
Subject: Re: [RFC PATCH 2/4] pio-mapping: Add ARM support for the PIOmapping API
Date: Mon, 08 Feb 2010 13:09:31 -0600 [thread overview]
Message-ID: <1265656171.6289.26.camel@mulgrave.site> (raw)
In-Reply-To: <1265652171.4020.165.camel@pc1117.cambridge.arm.com>
On Mon, 2010-02-08 at 18:02 +0000, Catalin Marinas wrote:
> If we do cache flushing in kunmap() we wouldn't need an additional cache
> flushing for highmem pages, so you can implement pio_kunmap()
> accordingly. James' point in a previous e-mail was that he doesn't want
> drivers to have "if (!PageHighMem(page))".
>
> Now, the ARM kunmap() function doesn't seem to do any flushing, only
> kunmap_atomic(). Do I miss anything?
>
> Also, for PIPT caches we don't actually create any D-cache aliases with
> kmap, so I'm not sure why we need to always flush the cache in kunmap().
Right ... this is why the implementation is arch specific. The PIPT
implementation would be a nop for lowmem and directly equivalent to the
corresponding kmap for highmem (no flushes ... unless there are platform
semantics requiring them because of the mappings that are in the kmaps
anyway).
James
next prev parent reply other threads:[~2010-02-08 19:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-05 16:31 [RFC PATCH 0/4] PIO drivers and cache coherency Catalin Marinas
2010-02-05 16:31 ` [RFC PATCH 1/4] pio-mapping: Add generic support for PIO mapping API Catalin Marinas
2010-02-05 16:31 ` [RFC PATCH 2/4] pio-mapping: Add ARM support for the " Catalin Marinas
2010-02-05 16:43 ` James Bottomley
2010-02-05 17:20 ` Catalin Marinas
2010-02-05 17:36 ` James Bottomley
2010-02-05 18:02 ` Catalin Marinas
2010-02-08 16:10 ` Catalin Marinas
2010-02-08 16:54 ` Russell King
2010-02-08 17:20 ` James Bottomley
2010-02-08 17:33 ` Russell King
2010-02-08 19:07 ` James Bottomley
2010-02-08 18:02 ` [RFC PATCH 2/4] pio-mapping: Add ARM support for the PIOmapping API Catalin Marinas
2010-02-08 19:09 ` James Bottomley [this message]
2010-02-08 17:14 ` [RFC PATCH 2/4] pio-mapping: Add ARM support for the PIO mapping API James Bottomley
2010-02-09 18:03 ` Catalin Marinas
2010-02-17 9:11 ` Benjamin Herrenschmidt
2010-02-17 20:04 ` Russell King
2010-02-17 20:39 ` Benjamin Herrenschmidt
2010-02-05 16:32 ` [RFC PATCH 3/4] pio-mapping: Use the PIO mapping API in libata-sff.c Catalin Marinas
2010-02-05 16:32 ` [RFC PATCH 4/4] pio-mapping: Use the PIO mapping API in the ISP1760 HCD driver Catalin Marinas
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