From 7d56cc2620f523eba7a831daa22186c8ae5bbdfe Mon Sep 17 00:00:00 2001 From: Douglas Anderson Date: Thu, 17 Dec 2015 11:15:21 -0800 Subject: [PATCH] usb: dwc2: Avoid more calls to dwc2_core_reset() Calls to dwc2_core_reset() are currently very slow, taking at least 150ms (possibly more). It behooves us to take as many of these calls out as possible. It turns out that the calls in dwc2_fs_phy_init() and dwc2_hs_phy_init() should (as documented in the code) only be needed if we need to do a PHY SELECT. That means that if we see that we can avoid the PHY SELECT then we can avoid the reset. This patch appears to successfully bypass two resets (one per USB device) on rk3288-based ARM Chromebooks. Signed-off-by: Douglas Anderson Signed-off-by: John Youn Signed-off-by: Felipe Balbi --- drivers/usb/dwc2/core.c | 40 +++++++++++++++++++++++----------------- 1 file changed, 23 insertions(+), 17 deletions(-) diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c index 9659dbd33c8c..c8f66ad48a55 100644 --- a/drivers/usb/dwc2/core.c +++ b/drivers/usb/dwc2/core.c @@ -553,16 +553,20 @@ static int dwc2_fs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) */ if (select_phy) { dev_dbg(hsotg->dev, "FS PHY selected\n"); + usbcfg = dwc2_readl(hsotg->regs + GUSBCFG); - usbcfg |= GUSBCFG_PHYSEL; - dwc2_writel(usbcfg, hsotg->regs + GUSBCFG); + if (!(usbcfg & GUSBCFG_PHYSEL)) { + usbcfg |= GUSBCFG_PHYSEL; + dwc2_writel(usbcfg, hsotg->regs + GUSBCFG); - /* Reset after a PHY select */ - retval = dwc2_core_reset(hsotg); - if (retval) { - dev_err(hsotg->dev, "%s() Reset failed, aborting", - __func__); - return retval; + /* Reset after a PHY select */ + retval = dwc2_core_reset(hsotg); + + if (retval) { + dev_err(hsotg->dev, + "%s: Reset failed, aborting", __func__); + return retval; + } } } @@ -597,13 +601,13 @@ static int dwc2_fs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) static int dwc2_hs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) { - u32 usbcfg; + u32 usbcfg, usbcfg_old; int retval = 0; if (!select_phy) return 0; - usbcfg = dwc2_readl(hsotg->regs + GUSBCFG); + usbcfg = usbcfg_old = dwc2_readl(hsotg->regs + GUSBCFG); /* * HS PHY parameters. These parameters are preserved during soft reset @@ -631,14 +635,16 @@ static int dwc2_hs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) break; } - dwc2_writel(usbcfg, hsotg->regs + GUSBCFG); + if (usbcfg != usbcfg_old) { + dwc2_writel(usbcfg, hsotg->regs + GUSBCFG); - /* Reset after setting the PHY parameters */ - retval = dwc2_core_reset(hsotg); - if (retval) { - dev_err(hsotg->dev, "%s() Reset failed, aborting", - __func__); - return retval; + /* Reset after setting the PHY parameters */ + retval = dwc2_core_reset(hsotg); + if (retval) { + dev_err(hsotg->dev, + "%s: Reset failed, aborting", __func__); + return retval; + } } return retval; -- 2.34.1