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authorEnrico Scholz <enrico.scholz@sigma-chemnitz.de>2008-07-17 20:09:30 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2008-08-13 17:32:53 -0700
commit3f02a957d5eb0eeb01207a799086f2b347077f71 (patch)
tree1e163aaabe6b260a168ab3c4744066d471f75fb4 /arch/sh/oprofile
parenta36c27dfd1003e6d6842fe77faaf868e3e6e9062 (diff)
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 <enrico.scholz@sigma-chemnitz.de> Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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