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From:   Krishna Kurapati <quic_kriskura@quicinc.com>
To:     Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Bjorn Andersson <andersson@kernel.org>
CC:     <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <quic_ppratap@quicinc.com>, <quic_wcheng@quicinc.com>,
        <quic_jackp@quicinc.com>,
        Krishna Kurapati <quic_kriskura@quicinc.com>,
        "Johan Hovold" <johan@kernel.org>
Subject: [PATCH v12 2/3] usb: dwc3: core: Skip setting event buffers for host only controllers
Date:   Wed, 4 Oct 2023 22:29:21 +0530
Message-ID: <20231004165922.25642-3-quic_kriskura@quicinc.com>
In-Reply-To: <20231004165922.25642-1-quic_kriskura@quicinc.com>
References: <20231004165922.25642-1-quic_kriskura@quicinc.com>
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Precedence: bulk

On some SoC's like SA8295P where the tertiary controller is host-only
capable, GEVTADDRHI/LO, GEVTSIZ, GEVTCOUNT registers are not accessible.
Trying to access them leads to a crash.

For DRD/Peripheral supported controllers, event buffer setup is done
again in gadget_pullup. Skip setup or cleanup of event buffers if
controller is host-only capable.

Suggested-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
 drivers/usb/dwc3/core.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index d7c5669ebd06..3e507e4cc542 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -486,6 +486,13 @@ static void dwc3_free_event_buffers(struct dwc3 *dwc)
 static int dwc3_alloc_event_buffers(struct dwc3 *dwc, unsigned int length)
 {
 	struct dwc3_event_buffer *evt;
+	unsigned int hw_mode;
+
+	hw_mode = DWC3_GHWPARAMS0_MODE(dwc->hwparams.hwparams0);
+	if (hw_mode == DWC3_GHWPARAMS0_MODE_HOST) {
+		dwc->ev_buf = NULL;
+		return 0;
+	}
 
 	evt = dwc3_alloc_one_event_buffer(dwc, length);
 	if (IS_ERR(evt)) {
@@ -507,6 +514,9 @@ int dwc3_event_buffers_setup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
 
+	if (!dwc->ev_buf)
+		return 0;
+
 	evt = dwc->ev_buf;
 	evt->lpos = 0;
 	dwc3_writel(dwc->regs, DWC3_GEVNTADRLO(0),
@@ -524,6 +534,9 @@ void dwc3_event_buffers_cleanup(struct dwc3 *dwc)
 {
 	struct dwc3_event_buffer	*evt;
 
+	if (!dwc->ev_buf)
+		return;
+
 	evt = dwc->ev_buf;
 
 	evt->lpos = 0;
-- 
2.42.0