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From:   Piyush Mehta <piyush.mehta@xilinx.com>
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        <krzysztof.kozlowski+dt@linaro.org>, <balbi@kernel.org>,
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        Piyush Mehta <piyush.mehta@xilinx.com>
Subject: [PATCH 2/2] usb: dwc3: core: Enable GUCTL1 bit 10 for fixing crc error after resume bug
Date:   Mon, 13 Jun 2022 18:17:03 +0530
Message-ID: <20220613124703.4493-3-piyush.mehta@xilinx.com>
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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 after EOR. This option is to support
certain legacy UTMI/ULPI PHYs.

Signed-off-by: Piyush Mehta <piyush.mehta@xilinx.com>
---
 drivers/usb/dwc3/core.c | 16 ++++++++++++++++
 drivers/usb/dwc3/core.h |  6 ++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index e027c0420dc3..8afc025390d2 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1140,6 +1140,20 @@ 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. Enabling bit 10 of GUCTL1
+	 * will correct this problem. This option is to support certain
+	 * legacy ULPI PHYs.
+	 */
+	if (dwc->enable_guctl1_resume_quirk) {
+		reg = dwc3_readl(dwc->regs, DWC3_GUCTL1);
+		reg |= DWC3_GUCTL1_RESUME_QUIRK;
+		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
+	}
+
 	if (!DWC3_VER_IS_PRIOR(DWC3, 250A)) {
 		reg = dwc3_readl(dwc->regs, DWC3_GUCTL1);
 
@@ -1483,6 +1497,8 @@ 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->enable_guctl1_resume_quirk = device_property_read_bool(dev,
+				"snps,enable_guctl1_resume_quirk");
 	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 81c486b3941c..e386209f0e1b 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -397,6 +397,9 @@
 #define DWC3_GUCTL_REFCLKPER_MASK		0xffc00000
 #define DWC3_GUCTL_REFCLKPER_SEL		22
 
+/* Global User Control Register 1 */
+#define DWC3_GUCTL1_RESUME_QUIRK		BIT(10)
+
 /* Global User Control Register 2 */
 #define DWC3_GUCTL2_RST_ACTBITLATER		BIT(14)
 
@@ -1093,6 +1096,8 @@ struct dwc3_scratchpad_array {
  *			change quirk.
  * @dis_tx_ipgap_linecheck_quirk: set if we disable u2mac linestate
  *			check during HS transmit.
+ * @enable_guctl1_resume_quirk: 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
@@ -1308,6 +1313,7 @@ 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		enable_guctl1_resume_quirk:1;
 	unsigned		parkmode_disable_ss_quirk:1;
 
 	unsigned		tx_de_emphasis_quirk:1;
-- 
2.17.1