linux-kernel - [PATCH V3 2/2] usb: dwc3: core: Enable GUCTL1 bit 10 for fixing termination error after resume bug

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Message-ID: <20220920052235.194272-3-piyush.mehta@amd.com>
Date:   Tue, 20 Sep 2022 10:52:35 +0530
From:   Piyush Mehta <piyush.mehta@....com>
To:     <gregkh@...uxfoundation.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <balbi@...nel.org>,
        <linux-usb@...r.kernel.org>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <git@....com>, <michal.simek@....com>,
        <siva.durga.prasad.paladugu@....com>,
        Piyush Mehta <piyush.mehta@....com>
Subject: [PATCH V3 2/2] usb: dwc3: core: Enable GUCTL1 bit 10 for fixing termination error after resume bug

When configured in HOST mode, after issuing U3/L2 exit controller fails
to send proper CRC checksum in CRC5 field. Because of this behavior
Transaction Error is generated, resulting in reset and re-enumeration of
usb device attached. Enabling chicken bit 10 of GUCTL1 will correct this
problem.

When this bit is set to '1', the UTMI/ULPI opmode will be changed to
"normal" along with HS terminations, term, and xcvr signals after EOR.
This option is to support certain legacy UTMI/ULPI PHYs.

Added "snps,resume-hs-terminations" quirk to resolved the above issue.

Signed-off-by: Piyush Mehta <piyush.mehta@....com>
---
 drivers/usb/dwc3/core.c | 17 +++++++++++++++++
 drivers/usb/dwc3/core.h |  4 ++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 8c8e32651473..7223074be6be 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1180,6 +1180,21 @@ static int dwc3_core_init(struct dwc3 *dwc)
 		dwc3_writel(dwc->regs, DWC3_GUCTL2, reg);
 	}
 
+	/*
+	 * When configured in HOST mode, after issuing U3/L2 exit controller
+	 * fails to send proper CRC checksum in CRC5 feild. Because of this
+	 * behaviour Transaction Error is generated, resulting in reset and
+	 * re-enumeration of usb device attached. All the termsel, xcvrsel,
+	 * opmode becomes 0 during end of resume. Enabling bit 10 of GUCTL1
+	 * will correct this problem. This option is to support certain
+	 * legacy ULPI PHYs.
+	 */
+	if (dwc->resume_hs_terminations) {
+		reg = dwc3_readl(dwc->regs, DWC3_GUCTL1);
+		reg |= DWC3_GUCTL1_RESUME_OPMODE_HS_HOST;
+		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
+	}
+
 	if (!DWC3_VER_IS_PRIOR(DWC3, 250A)) {
 		reg = dwc3_readl(dwc->regs, DWC3_GUCTL1);
 
@@ -1523,6 +1538,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				"snps,dis-del-phy-power-chg-quirk");
 	dwc->dis_tx_ipgap_linecheck_quirk = device_property_read_bool(dev,
 				"snps,dis-tx-ipgap-linecheck-quirk");
+	dwc->resume_hs_terminations = device_property_read_bool(dev,
+				"snps,resume-hs-terminations");
 	dwc->parkmode_disable_ss_quirk = device_property_read_bool(dev,
 				"snps,parkmode-disable-ss-quirk");
 
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 4fe4287dc934..bc5ac4d0d61f 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -263,6 +263,7 @@
 #define DWC3_GUCTL1_DEV_FORCE_20_CLK_FOR_30_CLK	BIT(26)
 #define DWC3_GUCTL1_DEV_L1_EXIT_BY_HW		BIT(24)
 #define DWC3_GUCTL1_PARKMODE_DISABLE_SS		BIT(17)
+#define DWC3_GUCTL1_RESUME_OPMODE_HS_HOST	BIT(10)
 
 /* Global Status Register */
 #define DWC3_GSTS_OTG_IP	BIT(10)
@@ -1096,6 +1097,8 @@ struct dwc3_scratchpad_array {
  *			change quirk.
  * @dis_tx_ipgap_linecheck_quirk: set if we disable u2mac linestate
  *			check during HS transmit.
+ * @resume-hs-terminations: Set if we enable quirk for fixing improper crc
+ *			generation after resume from suspend.
  * @parkmode_disable_ss_quirk: set if we need to disable all SuperSpeed
  *			instances in park mode.
  * @tx_de_emphasis_quirk: set if we enable Tx de-emphasis quirk
@@ -1311,6 +1314,7 @@ struct dwc3 {
 	unsigned		dis_u2_freeclk_exists_quirk:1;
 	unsigned		dis_del_phy_power_chg_quirk:1;
 	unsigned		dis_tx_ipgap_linecheck_quirk:1;
+	unsigned		resume_hs_terminations:1;
 	unsigned		parkmode_disable_ss_quirk:1;
 
 	unsigned		tx_de_emphasis_quirk:1;
-- 
2.25.1