From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx3.redhat.com (mx3.redhat.com [172.16.48.32]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id n3M9oLmn030407 for ; Wed, 22 Apr 2009 05:50:21 -0400 Received: from co203.xi-lite.net (co203.xi-lite.net [149.6.83.203]) by mx3.redhat.com (8.13.8/8.13.8) with ESMTP id n3M9o6nf000334 for ; Wed, 22 Apr 2009 05:50:06 -0400 Message-ID: <49EEE84A.5090400@parrot.com> Date: Wed, 22 Apr 2009 11:50:02 +0200 From: Matthieu CASTET MIME-Version: 1.0 To: "video4linux-list@redhat.com" Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Cc: Guennadi Liakhovetski Subject: videobuf-dma-contig sync question List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: video4linux-list-bounces@redhat.com Errors-To: video4linux-list-bounces@redhat.com List-ID: Hi, I don't understand why __videobuf_sync in videobuf-dma-contig isn't a nop. All the memory allocated by videobuf-dma-contig is coherent memory. And Documentation/DMA-API.txt seems to imply that this memory is coherent and doesn't need extra cache operation for synchronization. Also calling dma_sync_single_for_cpu cause panic on arm for per-device coherent memory, because the memory isn't in the main memory[1]. Why __videobuf_sync need dma_sync_single_for_cpu ? Regards, Matthieu [1] void dma_cache_maint(const void *start, size_t size, int direction) { const void *end = start + size; BUG_ON(!virt_addr_valid(start) || !virt_addr_valid(end - 1)); -- video4linux-list mailing list Unsubscribe mailto:video4linux-list-request@redhat.com?subject=unsubscribe https://www.redhat.com/mailman/listinfo/video4linux-list