From 153e3979201b76dbd5788f032fb683e95121e159 Mon Sep 17 00:00:00 2001 From: Clemens Ladisch Date: Thu, 10 Jun 2010 08:22:07 +0200 Subject: [PATCH] firewire: ohci: speed up PHY register accesses Most PHY chips, when idle, can complete a register access in the time needed for two or three PCI read transactions; bigger delays occur only when data is currently being moved over the link/PHY interface. So if we busy-wait a few times when waiting for the register access to finish, it is likely that we can finish without having to sleep. Signed-off-by: Clemens Ladisch --- drivers/firewire/ohci.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c index de5ff376231c..65b9bdb8541a 100644 --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -474,12 +474,17 @@ static int read_phy_reg(struct fw_ohci *ohci, int addr) int i; reg_write(ohci, OHCI1394_PhyControl, OHCI1394_PhyControl_Read(addr)); - for (i = 0; i < 10; i++) { + for (i = 0; i < 3 + 100; i++) { val = reg_read(ohci, OHCI1394_PhyControl); if (val & OHCI1394_PhyControl_ReadDone) return OHCI1394_PhyControl_ReadData(val); - msleep(1); + /* + * Try a few times without waiting. Sleeping is necessary + * only when the link/PHY interface is busy. + */ + if (i >= 3) + msleep(1); } fw_error("failed to read phy reg\n"); @@ -492,12 +497,13 @@ static int write_phy_reg(const struct fw_ohci *ohci, int addr, u32 val) reg_write(ohci, OHCI1394_PhyControl, OHCI1394_PhyControl_Write(addr, val)); - for (i = 0; i < 100; i++) { + for (i = 0; i < 3 + 100; i++) { val = reg_read(ohci, OHCI1394_PhyControl); if (!(val & OHCI1394_PhyControl_WritePending)) return 0; - msleep(1); + if (i >= 3) + msleep(1); } fw_error("failed to write phy reg\n"); -- 2.30.2