linux-kernel - [PATCH] ufs: scsi: core: Send a NOP OUT to device before disabling AHIT

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Message-ID: <20250617073702.1207412-1-mrigankac@google.com>
Date: Tue, 17 Jun 2025 07:37:02 +0000
From: Mriganka Chakravarty <mrigankac@...gle.com>
To: Alim Akhtar <alim.akhtar@...sung.com>, Avri Altman <avri.altman@....com>, 
	Bart Van Assche <bvanassche@....org>, Peter Wang <peter.wang@...iatek.com>, 
	Manivannan Sadhasivam <mani@...nel.org>, "Bao D . Nguyen" <quic_nguyenb@...cinc.com>, 
	Eric Biggers <ebiggers@...gle.com>, Can Guo <quic_cang@...cinc.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>
Cc: linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org, 
	manugautam@...gle.com, vamshigajjela@...gle.com, 
	Mriganka Chakravarty <mrigankac@...gle.com>
Subject: [PATCH] ufs: scsi: core: Send a NOP OUT to device before disabling AHIT

Synopsis databook recommends that the host must send a NOP OUT to device
before disabling AHIT(setting AHIT.AH8ITV to 0), if already programmed
to a non-zero value.

Signed-off-by: Mriganka Chakravarty <mrigankac@...gle.com>
---
 drivers/ufs/core/ufshcd.c | 10 ++++++++++
 include/ufs/ufshcd.h      |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 4410e7d93b7d..f9a2d15ab2ee 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -4507,9 +4507,19 @@ EXPORT_SYMBOL_GPL(ufshcd_uic_hibern8_exit);
 
 static void ufshcd_configure_auto_hibern8(struct ufs_hba *hba)
 {
+	u32 reg_ahit;
+
 	if (!ufshcd_is_auto_hibern8_supported(hba))
 		return;
 
+	if (hba->quirks & UFSHCD_QUIRK_SEND_NOP_BEFORE_AHIT_DISABLE) {
+		reg_ahit = ufshcd_readl(hba, REG_AUTO_HIBERNATE_IDLE_TIMER);
+		if (hba->ahit == 0 &&
+		    FIELD_GET(UFSHCI_AHIBERN8_TIMER_MASK, reg_ahit) != 0)
+			ufshcd_exec_dev_cmd(hba, DEV_CMD_TYPE_NOP,
+					    hba->nop_out_timeout);
+	}
+
 	ufshcd_writel(hba, hba->ahit, REG_AUTO_HIBERNATE_IDLE_TIMER);
 }
 
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 9b3515cee711..b069d15c1c71 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -689,6 +689,13 @@ enum ufshcd_quirks {
 	 * single doorbell mode.
 	 */
 	UFSHCD_QUIRK_BROKEN_LSDBS_CAP			= 1 << 25,
+
+	/*
+	 * This quirk indicates that host must send a NOP OUT to device before
+	 * disabling AHIT(setting AHIT.AH8ITV to 0), if already programmed to a
+	 * non-zero value.
+	 */
+	UFSHCD_QUIRK_SEND_NOP_BEFORE_AHIT_DISABLE	= 1 << 31,
 };
 
 enum ufshcd_caps {
-- 
2.50.0.rc2.692.g299adb8693-goog