From: Sergej Pupykin <ps@lx-ltd.ru>
To: Arjan van de Ven <arjan@infradead.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Bugs in usb-skeleton.c??? :)
Date: 13 Jul 2006 16:33:35 +0400 [thread overview]
Message-ID: <m37j2helb4.fsf@lx-ltd.ru> (raw)
In-Reply-To: <1152791917.3024.39.camel@laptopd505.fenrus.org>
>> As I understand, USB subsystem uses urb->transfer_buffer directly with
>> DMA. I see that usb-skeleton.c and (at least) bluez's hci_usb allocates it
>> without GFP_DMA flag. (skeleton with GFP_KERNEL, bluez with GFP_ATOMIC)
AvdV> I think GFP_DMA means something different than that you think it means.
AvdV> GFP_DMA is a bad old hack that means "this is for ISA bus cards to DMA
AvdV> to/from". Since there are no ISA bus USB controllers... the USB code
AvdV> doesn't need to use GFP_DMA.
Does kmalloc always allocate pages that can be used in DMA?
I see pci_map_single gives address that incremented later without page
boundary checking. Are allocated pages sequented? (usb-ohci.c)
next prev parent reply other threads:[~2006-07-13 12:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-07-13 11:26 Bugs in usb-skeleton.c??? :) Sergej Pupykin
2006-07-13 11:58 ` Arjan van de Ven
2006-07-13 12:33 ` Sergej Pupykin [this message]
2006-07-13 13:00 ` Arjan van de Ven
2006-07-13 13:10 ` Sergej Pupykin
2006-07-13 14:24 ` Manuel Lauss
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