From mboxrd@z Thu Jan 1 00:00:00 1970 From: benh@kernel.crashing.org (Benjamin Herrenschmidt) Date: Thu, 25 Feb 2010 08:13:56 +1100 Subject: USB mass storage and ARM cache coherency In-Reply-To: References: Message-ID: <1267046036.23523.1693.camel@pasglop> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 2010-02-24 at 11:19 -0500, Alan Stern wrote: > > It is but I'm not confident the responsibility for doing that > cleanup > > is at the HCD level. That would impact a lot of HCD activities that > > don't need such flushing since the use of the page is purely > in-kernel. > > That's right. The HCD merely puts data wherever it's told to. It > doesn't know whether the destination is in the page cache, in > userspace, or anywhere else. The same is true for usb-storage. I'm surprised that usb-storage has an issue here. It shouldn't afaik, since it's just a SCSI driver (or not anymore ?) and the BIO or filesystems handle things there no ? I haven't seen a single call to flush_dcache_page() in any of drivers/scsi, drivers/ata or drivers/ide when I looked... Cheers, Ben.