USB mass storage and ARM cache coherency
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From: Oliver Neukum on 2 Feb 2010 06:50 Am Montag, 1. Februar 2010 18:29:14 schrieb Catalin Marinas: > + if (usb_pipein(urb->pipe) && usb_pipetype(urb->pipe) == PIPE_BULK) { > + void *ptr; > + for (ptr = urb->transfer_buffer; > + ptr < urb->transfer_buffer + urb->transfer_buffer_length; > + ptr += PAGE_SIZE) > + flush_dcache_page(virt_to_page(ptr)); Is it correct to limit this to BULK pipes? Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Catalin Marinas on 2 Feb 2010 07:10 On Tue, 2010-02-02 at 11:48 +0000, Oliver Neukum wrote: > Am Montag, 1. Februar 2010 18:29:14 schrieb Catalin Marinas: > > + if (usb_pipein(urb->pipe) && usb_pipetype(urb->pipe) == PIPE_BULK) { > > + void *ptr; > > + for (ptr = urb->transfer_buffer; > > + ptr < urb->transfer_buffer + urb->transfer_buffer_length; > > + ptr += PAGE_SIZE) > > + flush_dcache_page(virt_to_page(ptr)); > > Is it correct to limit this to BULK pipes? I'm not entirely sure. The flush_dcache_page() should only be called for pages that may be mapped into user space (page cache pages). We don't need this for control buffers. It was my impression that what's coming from the mass storage layer intended for page cache pages has the PIPE_BULK type (I may be wrong though). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Oliver Neukum on 2 Feb 2010 07:10 Am Dienstag, 2. Februar 2010 13:01:12 schrieb Catalin Marinas: > On Tue, 2010-02-02 at 11:48 +0000, Oliver Neukum wrote: > > Am Montag, 1. Februar 2010 18:29:14 schrieb Catalin Marinas: > > > + if (usb_pipein(urb->pipe) && usb_pipetype(urb->pipe) == PIPE_BULK) { > > > + void *ptr; > > > + for (ptr = urb->transfer_buffer; > > > + ptr < urb->transfer_buffer + urb->transfer_buffer_length; > > > + ptr += PAGE_SIZE) > > > + flush_dcache_page(virt_to_page(ptr)); > > > > Is it correct to limit this to BULK pipes? > > I'm not entirely sure. The flush_dcache_page() should only be called for > pages that may be mapped into user space (page cache pages). We don't > need this for control buffers. It was my impression that what's coming > from the mass storage layer intended for page cache pages has the > PIPE_BULK type (I may be wrong though). For storage that is correct. But what about other sources of pages, for example iSCSI? Regards Oliver -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Andreas Mohr on 2 Feb 2010 07:20 Hi, On Tue, Feb 02, 2010 at 01:07:56PM +0100, Oliver Neukum wrote: > Am Dienstag, 2. Februar 2010 13:01:12 schrieb Catalin Marinas: > > On Tue, 2010-02-02 at 11:48 +0000, Oliver Neukum wrote: > > > Am Montag, 1. Februar 2010 18:29:14 schrieb Catalin Marinas: > > > Is it correct to limit this to BULK pipes? > > > > I'm not entirely sure. The flush_dcache_page() should only be called for > > pages that may be mapped into user space (page cache pages). We don't > > need this for control buffers. It was my impression that what's coming > > from the mass storage layer intended for page cache pages has the > > PIPE_BULK type (I may be wrong though). > > For storage that is correct. But what about other sources of pages, > for example iSCSI? Or... usb-audio? I should have verified that it is using bulk endpoints (and thus the patch applies to my case). usb-audio probably uses isochronous transfers, thus that would be an obvious reason why the patch didn't work for me. (with some other reason possibly being BCM4710 issues, of course) Andreas Mohr -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Catalin Marinas on 2 Feb 2010 07:50
On Tue, 2010-02-02 at 12:07 +0000, Oliver Neukum wrote: > Am Dienstag, 2. Februar 2010 13:01:12 schrieb Catalin Marinas: > > On Tue, 2010-02-02 at 11:48 +0000, Oliver Neukum wrote: > > > Am Montag, 1. Februar 2010 18:29:14 schrieb Catalin Marinas: > > > > + if (usb_pipein(urb->pipe) && usb_pipetype(urb->pipe) == PIPE_BULK) { > > > > + void *ptr; > > > > + for (ptr = urb->transfer_buffer; > > > > + ptr < urb->transfer_buffer + urb->transfer_buffer_length; > > > > + ptr += PAGE_SIZE) > > > > + flush_dcache_page(virt_to_page(ptr)); > > > > > > Is it correct to limit this to BULK pipes? > > > > I'm not entirely sure. The flush_dcache_page() should only be called for > > pages that may be mapped into user space (page cache pages). We don't > > need this for control buffers. It was my impression that what's coming > > from the mass storage layer intended for page cache pages has the > > PIPE_BULK type (I may be wrong though). > > For storage that is correct. But what about other sources of pages, > for example iSCSI? In the iSCSI case, does the HCD driver write directly to a page cache page? Or it just fills in network packets that are copied to page cache pages by the iSCSI code (sorry, I'm not familiar with this part of the kernel). If the latter, the cache flushing in the HCD driver would not help and it needs to be done in the iSCSI code. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |