From: Enrico Scholz Date: Thu, 17 Jul 2008 18:09:30 +0000 (+0200) Subject: usb: ISP1760: improve pre-fetch timing X-Git-Tag: v2.6.27-rc4~101^2~20 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f02a957d5eb0eeb01207a799086f2b347077f71;p=pandora-kernel.git usb: ISP1760: improve pre-fetch timing ISP1760 requires a delay of 90ns between programming the address and reading the data. Current driver solves this by a mdelay(1) which is very heavy weighted and slow. This patch applies the workaround from the ISP1760 FAQ by using two different banks for PTD and payload data and using a common wait for them. This wait is done by an additional ISP1760 access (whose timing constraints guarantee the 90ns delay). This improves speed when reading from an USB stick from: $ time dd if=/dev/sda of=/dev/zero bs=65536 count=1638 real 1m 15.43s user 0m 0.44s sys 0m 39.46s to $ time dd if=/dev/sda of=/dev/zero bs=65536 count=1638 real 0m 18.53s user 0m 0.16s sys 0m 12.97s [bigeasy@linutronix.de: fixed comment formating, moved define into header file, obey 80 char rule] Signed-off-by: Enrico Scholz Signed-off-by: Sebastian Siewior Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed