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From:   Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
To:     ulf.hansson@linaro.org, adrian.hunter@intel.com
Cc:     asutoshd@codeaurora.org, stummala@codeaurora.org,
        sayalil@codeaurora.org, cang@codeaurora.org,
        rampraka@codeaurora.org, linux-mmc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        Ritesh Harjani <riteshh@codeaurora.org>,
        Veerabhadrarao Badiganti <vbadigan@codeaurora.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>
Subject: [PATCH V1] mmc: sdhci-msm: Don't enable PWRSAVE_DLL for certain sdhc hosts
Date:   Fri,  7 Feb 2020 13:31:56 +0530
Message-Id: <1581062518-11655-1-git-send-email-vbadigan@codeaurora.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Ritesh Harjani <riteshh@codeaurora.org>

SDHC core with new 14lpp and later tech DLL should not enable
PWRSAVE_DLL since such controller's internal gating cannot meet
following MCLK requirement:
When MCLK is gated OFF, it is not gated for less than 0.5us and MCLK
must be switched on for at-least 1us before DATA starts coming.

Adding support for this requirement.

Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
---
 drivers/mmc/host/sdhci-msm.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index c3a160c..f27f891 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -977,9 +977,21 @@ static int sdhci_msm_cm_dll_sdc4_calibration(struct sdhci_host *host)
 		goto out;
 	}
 
-	config = readl_relaxed(host->ioaddr + msm_offset->core_vendor_spec3);
-	config |= CORE_PWRSAVE_DLL;
-	writel_relaxed(config, host->ioaddr + msm_offset->core_vendor_spec3);
+	/*
+	 * Set CORE_PWRSAVE_DLL bit in CORE_VENDOR_SPEC3.
+	 * When MCLK is gated OFF, it is not gated for less than 0.5us
+	 * and MCLK must be switched on for at-least 1us before DATA
+	 * starts coming. Controllers with 14lpp and later tech DLL cannot
+	 * guarantee above requirement. So PWRSAVE_DLL should not be
+	 * turned on for host controllers using this DLL.
+	 */
+	if (msm_host->use_14lpp_dll_reset) {
+		config = readl_relaxed(host->ioaddr +
+				msm_offset->core_vendor_spec3);
+		config |= CORE_PWRSAVE_DLL;
+		writel_relaxed(config, host->ioaddr +
+				msm_offset->core_vendor_spec3);
+	}
 
 	/*
 	 * Drain writebuffer to ensure above DLL calibration
-- 
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