From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: netdev@vger.kernel.org, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] Don't call request_region() for 3C90x chips
Date: Wed, 19 Jul 2006 23:08:20 +0400 [thread overview]
Message-ID: <44BE8324.2060103@ru.mvista.com> (raw)
In-Reply-To: <44BE7291.2080306@pobox.com>
Hello.
Jeff Garzik wrote:
>> It's generally not a good idea to call request_region() on an address
>> returned by pci_iomap(), even less so on a MMIO address. And there was
>> absolutely no point in claiming the region already claimed by the PCI
>> core, especially with the same PCI generic owner's name. As this is
>> the only case of the must_free_region flag being set, this flag may go
>> away as well...
>> Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
> I agree you have identified a bug, but this is not a solution.
> The current driver bug is that it calls request_region() potentially on
> an MMIO address, but the solution is _not_ to completely avoid reserving
> the resource.
It's not even a MMIO/PIO address anymore after pci_iomap() -- it either
went thru ioremap() or ioport_map() which both change the mapping from the
physical to the virtual address (or some equivalent of it for I/O ports).
> The region registered with the PCI core, but _not_ claimed by anyone.
> Someone still needs to either call pci_{request,release}_regions() or
> request_[mem_]region() to indicate that the resource is reserved.
Sigh, it seems I've missed that difference. So, I'll recast...
> This bug you have found was probably a missed detail during the
> conversion to the iomap API.
Well, not only that: it was wrong once the driver started using MMIO
(which is of course a preference).
> Jeff
WBR, Sergei
next prev parent reply other threads:[~2006-07-19 19:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-10 18:25 [PATCH] Don't call request_region() for 3C90x chips Sergei Shtylylov
2006-07-19 17:57 ` Jeff Garzik
2006-07-19 19:08 ` Sergei Shtylyov [this message]
2006-07-19 19:22 ` Jeff Garzik
2006-07-27 19:22 ` Sergei Shtylyov
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