From patchwork Tue Aug 2 05:54:31 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: bernie@plugable.com X-Patchwork-Id: 1028112 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.4) with ESMTP id p725tA2K005445 for ; Tue, 2 Aug 2011 05:55:21 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750934Ab1HBFzV (ORCPT ); Tue, 2 Aug 2011 01:55:21 -0400 Received: from mail-yw0-f46.google.com ([209.85.213.46]:45705 "EHLO mail-yw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773Ab1HBFzU (ORCPT ); Tue, 2 Aug 2011 01:55:20 -0400 Received: by ywn13 with SMTP id 13so1142918ywn.19 for ; Mon, 01 Aug 2011 22:55:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer:in-reply-to :references; bh=RKrE23B3QpG1I+fERsBFGm36Ihj78Q6x0C3AEnUB/IU=; b=P2DVkprIKsNDOX3qgXV95P4PxCxGVJR+KSG+jTTfWMRiuOctaCAIU8bBPuKWvBW+EY NLrIUyl+/VCA2vWcVkbvy/NiMcaN6uLsbxvN1hNhd+YND0GkRN9nIuya8jeWvSa8l5Ah DKZFvKSkSVLHu1ufjIFXjcsvMyQS+z/Fy+qac= Received: by 10.42.29.7 with SMTP id p7mr3133613icc.270.1312264519946; Mon, 01 Aug 2011 22:55:19 -0700 (PDT) Received: from localhost.localdomain (c-76-22-58-200.hsd1.wa.comcast.net [76.22.58.200]) by mx.google.com with ESMTPS id a10sm3851396iba.58.2011.08.01.22.55.18 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 01 Aug 2011 22:55:19 -0700 (PDT) From: bernie@plugable.com To: linux-fbdev@vger.kernel.org Cc: lethal@linux-sh.org, Stuart Hopkins , Bernie Thompson Subject: [PATCH 4/5] udlfb: Add module option to do without shadow framebuffer Date: Mon, 1 Aug 2011 22:54:31 -0700 Message-Id: <1312264472-2900-4-git-send-email-bernie@plugable.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1312264472-2900-1-git-send-email-bernie@plugable.com> References: <1312264472-2900-1-git-send-email-bernie@plugable.com> Sender: linux-fbdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Tue, 02 Aug 2011 05:55:22 +0000 (UTC) From: Stuart Hopkins By default, udlfb allocates a 2nd buffer to shadow what's across the bus on the USB device. It can operate without this shadow, but then it cannot tell which pixels have changed, and must send all. Saves host memory, but worsens the USB 2.0 bus bottleneck. This option allows users in very low memory situations (e.g. bifferboard) to optionally turn off this shadow framebuffer. Signed-off-by: Bernie Thompson Signed-off-by: Stuart Hopkins --- Documentation/fb/udlfb.txt | 5 +++++ drivers/video/udlfb.c | 10 ++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/Documentation/fb/udlfb.txt b/Documentation/fb/udlfb.txt index 7fdde2a..473ceed 100644 --- a/Documentation/fb/udlfb.txt +++ b/Documentation/fb/udlfb.txt @@ -105,6 +105,11 @@ console Allow fbcon to attach to udlfb provided framebuffers. This the first framebuffer it finds, which isn't usually what the user wants in the case of USB displays. +shadow Allocate a 2nd framebuffer to shadow what's currently across + the USB bus in device memory. If any pixels are unchanged, + do not transmit. Spends host memory to save USB transfers. + Enabled by default. Only disable on very low memory systems. + Sysfs Attributes ================ diff --git a/drivers/video/udlfb.c b/drivers/video/udlfb.c index f5df3d3..5a13dc5 100644 --- a/drivers/video/udlfb.c +++ b/drivers/video/udlfb.c @@ -72,6 +72,7 @@ MODULE_DEVICE_TABLE(usb, id_table); /* module options */ static int console; /* Optionally allow fbcon to consume first framebuffer */ static int fb_defio; /* Optionally enable experimental fb_defio mmap support */ +static int shadow = 1; /* Optionally disable shadow framebuffer */ /* dlfb keeps a list of urbs for efficient bulk transfers */ static void dlfb_urb_completion(struct urb *urb); @@ -1158,7 +1159,7 @@ static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info) int new_len; unsigned char *old_fb = info->screen_base; unsigned char *new_fb; - unsigned char *new_back; + unsigned char *new_back = 0; pr_warn("Reallocating framebuffer. Addresses will change!\n"); @@ -1190,7 +1191,8 @@ static int dlfb_realloc_framebuffer(struct dlfb_data *dev, struct fb_info *info) * But with imperfect damage info we may send pixels over USB * that were, in fact, unchanged - wasting limited USB bandwidth */ - new_back = vzalloc(new_len); + if (shadow) + new_back = vzalloc(new_len); if (!new_back) pr_info("No shadow/backing buffer allocated\n"); else { @@ -1603,6 +1605,7 @@ static int dlfb_usb_probe(struct usb_interface *interface, usbdev->descriptor.bcdDevice, dev); pr_info("console enable=%d\n", console); pr_info("fb_defio enable=%d\n", fb_defio); + pr_info("shadow enable=%d\n", shadow); dev->sku_pixel_limit = 2048 * 1152; /* default to maximum */ @@ -1960,6 +1963,9 @@ MODULE_PARM_DESC(console, "Allow fbcon to consume first framebuffer found"); module_param(fb_defio, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP); MODULE_PARM_DESC(fb_defio, "Enable fb_defio mmap support. *Experimental*"); +module_param(shadow, bool, S_IWUSR | S_IRUSR | S_IWGRP | S_IRGRP); +MODULE_PARM_DESC(shadow, "Shadow vid mem. Disable to save mem but lose perf"); + MODULE_AUTHOR("Roberto De Ioris , " "Jaya Kumar , " "Bernie Thompson ");