From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754125AbXISFo1 (ORCPT ); Wed, 19 Sep 2007 01:44:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751707AbXISFoU (ORCPT ); Wed, 19 Sep 2007 01:44:20 -0400 Received: from mail.queued.net ([207.210.101.209]:3446 "EHLO mail.queued.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751540AbXISFoT (ORCPT ); Wed, 19 Sep 2007 01:44:19 -0400 Date: Wed, 19 Sep 2007 01:44:18 -0400 From: Andres Salomon To: video4linux-list@redhat.com Cc: v4l-dvb-maintainer@linuxtv.org, corbet@lwn.net, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH] cafe_ccic: default to allocating DMA buffers at probe time Message-Id: <20070919014418.073543bc.dilinger@queued.net> X-Mailer: Sylpheed 2.4.5 (GTK+ 2.10.13; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org By default, we allocate DMA buffers when actually reading from the video capture device. On a system with 128MB or 256MB of ram, it's very easy for that memory to quickly become fragmented. We've had users report having 30+MB of memory free, but the cafe_ccic driver is still unable to allocate DMA buffers. Our workaround has been to make use of the 'alloc_bufs_at_load' parameter to allocate DMA buffers during device probing. This patch makes DMA buffer allocation happen during device probe by default, and changes the parameter to 'alloc_bufs_at_read'. The camera hardware is there, if the cafe_ccic driver is enabled/loaded it should do its best to ensure that the camera is actually usable; delaying DMA buffer allocation saves an insignicant amount of memory, and causes the driver to be much less useful. --- drivers/media/video/cafe_ccic.c | 18 +++++++++--------- 1 files changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/media/video/cafe_ccic.c b/drivers/media/video/cafe_ccic.c index ef53618..3588a59 100644 --- a/drivers/media/video/cafe_ccic.c +++ b/drivers/media/video/cafe_ccic.c @@ -63,13 +63,13 @@ MODULE_SUPPORTED_DEVICE("Video"); */ #define MAX_DMA_BUFS 3 -static int alloc_bufs_at_load = 0; -module_param(alloc_bufs_at_load, bool, 0444); -MODULE_PARM_DESC(alloc_bufs_at_load, - "Non-zero value causes DMA buffers to be allocated at module " - "load time. This increases the chances of successfully getting " - "those buffers, but at the cost of nailing down the memory from " - "the outset."); +static int alloc_bufs_at_read = 0; +module_param(alloc_bufs_at_read, bool, 0444); +MODULE_PARM_DESC(alloc_bufs_at_read, + "Non-zero value causes DMA buffers to be allocated when the " + "video capture device is read, rather than at module load " + "time. This saves memory, but decreases the chances of " + "successfully getting those buffers."); static int n_dma_bufs = 3; module_param(n_dma_bufs, uint, 0644); @@ -1503,7 +1503,7 @@ static int cafe_v4l_release(struct inode *inode, struct file *filp) } if (cam->users == 0) { cafe_ctlr_power_down(cam); - if (! alloc_bufs_at_load) + if (alloc_bufs_at_read) cafe_free_dma_bufs(cam); } mutex_unlock(&cam->s_mutex); @@ -2162,7 +2162,7 @@ static int cafe_pci_probe(struct pci_dev *pdev, /* * If so requested, try to get our DMA buffers now. */ - if (alloc_bufs_at_load) { + if (!alloc_bufs_at_read) { if (cafe_alloc_dma_bufs(cam, 1)) cam_warn(cam, "Unable to alloc DMA buffers at load" " will try again later.");