[PATCH 07/10] usb: chipidea: msm: do not force the TX FIFO idle on HSIC instances

From: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
To: Bartosz Golaszewski <brgl@kernel.org>,
	Bjorn Andersson <andersson@kernel.org>,
	Linus Walleij <linusw@kernel.org>, Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Xu Yang <xu.yang_2@nxp.com>, Peng Fan <peng.fan@nxp.com>,
	Vinod Koul <vkoul@kernel.org>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Peter Chen <peter.chen@kernel.org>,
	Pavankumar Kondeti <quic_pkondeti@quicinc.com>,
	Stephen Boyd <stephen.boyd@linaro.org>,
	Konrad Dybcio <konradybcio@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
	linux-arm-msm@vger.kernel.org, linux-gpio@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-usb@vger.kernel.org, linux-phy@lists.infradead.org,
	Greg Kroah-Hartman <gregkh@suse.de>,
	Peter Chen <peter.chen@nxp.com>
Subject: [PATCH 07/10] usb: chipidea: msm: do not force the TX FIFO idle on HSIC instances
Date: Mon, 10 Aug 2026 18:42:11 +0300	[thread overview]
Message-ID: <20260810-msm8974-usb-hsic-v1-7-e5f93ea76ffa@oss.qualcomm.com> (raw)
In-Reply-To: <20260810-msm8974-usb-hsic-v1-0-e5f93ea76ffa@oss.qualcomm.com>

The controller reset handler unconditionally clears
GENCONFIG[TXFIFO_IDLE_FORCE_DIS] as a workaround for an RX buffer
collision issue. The vendor HSIC host driver never applies this
workaround on the HSIC instances and leaves the bit at its power-on
default (set), so clearing it makes the HSIC instance diverge from the
known-working configuration.

Skip the workaround for HSIC instances, like the neighbouring
GENCONFIG_2 write already does.

Fixes: 47654a162081 ("usb: chipidea: msm: Restore wrapper settings after reset")
Assisted-by: Claude:claude-fable-5
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
---
 drivers/usb/chipidea/ci_hdrc_msm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/chipidea/ci_hdrc_msm.c b/drivers/usb/chipidea/ci_hdrc_msm.c
index 9a9410a814e5..69be194f8e27 100644
--- a/drivers/usb/chipidea/ci_hdrc_msm.c
+++ b/drivers/usb/chipidea/ci_hdrc_msm.c
@@ -108,8 +108,9 @@ static int ci_hdrc_msm_notify_event(struct ci_hdrc *ci, unsigned event)
 		hw_write_id_reg(ci, HS_PHY_AHB_MODE, 0xffffffff, 0x8);
 
 		/* workaround for rx buffer collision issue */
-		hw_write_id_reg(ci, HS_PHY_GENCONFIG,
-				HS_PHY_TXFIFO_IDLE_FORCE_DIS, 0);
+		if (!msm_ci->hsic)
+			hw_write_id_reg(ci, HS_PHY_GENCONFIG,
+					HS_PHY_TXFIFO_IDLE_FORCE_DIS, 0);
 
 		if (!msm_ci->hsic)
 			hw_write_id_reg(ci, HS_PHY_GENCONFIG_2,

-- 
2.47.3


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