Re: [PATCH] usb: dwc2: Don't reset the core after setting turnaround time
From: Minas Harutyunyan <hidden>
Date: 2021-06-14 12:43:15
On 6/3/2021 7:59 PM, Clément Lassieur wrote:
Every time the hub signals a reset while we (device) are hsotg->connected,
dwc2_hsotg_core_init_disconnected() is called, which in turn calls
dwc2_hs_phy_init().
GUSBCFG.USBTrdTim is cleared upon Core Soft Reset, so if
hsotg->params.phy_utmi_width is 8-bit, the value of GUSBCFG.USBTrdTim (the
default one: 0x5, corresponding to 16-bit) is always different from
hsotg->params.phy_utmi_width, thus dwc2_core_reset() is called every
time (usbcfg != usbcfg_old), which causes 2 issues:
1) The call to dwc2_core_reset() does another reset 300us after the initial
Chirp K of the first reset (which should last at least Tuch = 1ms), and
messes up the High-speed Detection Handshake: both hub and device drive
current into the D+ and D- lines at the same time.
2) GUSBCFG.USBTrdTim is cleared by the second reset, so its value is always
the default one (0x5).
Setting GUSBCFG.USBTrdTim after the potential call to dwc2_core_reset()
fixes both issues. It is now set even when select_phy is false because the
cost of the Core Soft Reset is removed.
Fixes: 1e868545f2bb ("usb: dwc2: gadget: Move gadget phy init into core phy init")
Signed-off-by: Clément Lassieur <redacted>Acked-by: Minas Harutyunyan <redacted>
quoted hunk ↗ jump to hunk
--- drivers/usb/dwc2/core.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-)diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c index 6f70ab9577b4..272ae5722c86 100644 --- a/drivers/usb/dwc2/core.c +++ b/drivers/usb/dwc2/core.c@@ -1111,15 +1111,6 @@ static int dwc2_hs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) usbcfg &= ~(GUSBCFG_ULPI_UTMI_SEL | GUSBCFG_PHYIF16); if (hsotg->params.phy_utmi_width == 16) usbcfg |= GUSBCFG_PHYIF16; - - /* Set turnaround time */ - if (dwc2_is_device_mode(hsotg)) { - usbcfg &= ~GUSBCFG_USBTRDTIM_MASK; - if (hsotg->params.phy_utmi_width == 16) - usbcfg |= 5 << GUSBCFG_USBTRDTIM_SHIFT; - else - usbcfg |= 9 << GUSBCFG_USBTRDTIM_SHIFT; - } break; default: dev_err(hsotg->dev, "FS PHY selected at HS!\n");@@ -1141,6 +1132,24 @@ static int dwc2_hs_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) return retval; } +static void dwc2_set_turnaround_time(struct dwc2_hsotg *hsotg) +{ + u32 usbcfg; + + if (hsotg->params.phy_type != DWC2_PHY_TYPE_PARAM_UTMI) + return; + + usbcfg = dwc2_readl(hsotg, GUSBCFG); + + usbcfg &= ~GUSBCFG_USBTRDTIM_MASK; + if (hsotg->params.phy_utmi_width == 16) + usbcfg |= 5 << GUSBCFG_USBTRDTIM_SHIFT; + else + usbcfg |= 9 << GUSBCFG_USBTRDTIM_SHIFT; + + dwc2_writel(hsotg, usbcfg, GUSBCFG); +} + int dwc2_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) { u32 usbcfg;@@ -1158,6 +1167,9 @@ int dwc2_phy_init(struct dwc2_hsotg *hsotg, bool select_phy) retval = dwc2_hs_phy_init(hsotg, select_phy); if (retval) return retval; + + if (dwc2_is_device_mode(hsotg)) + dwc2_set_turnaround_time(hsotg); } if (hsotg->hw_params.hs_phy_type == GHWCFG2_HS_PHY_TYPE_ULPI &&