Re: [PATCH V2] mmc: sdhci-msm: Don't enable PWRSAVE_DLL for certain sdhc hosts

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 2020-02-07 20:04, Veerabhadrarao Badiganti wrote:
From: Ritesh Harjani <riteshh@xxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxx>
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@xxxxxxxxxxxxxx>
--

Reviewed-by: Can Guo <cang@xxxxxxxxxxxxxx>


Changes since V1:
  Condition was not correct in V1, which is corrected in V2

--
---
 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..aa5b610 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



[Index of Archives]     [Linux Memonry Technology]     [Linux USB Devel]     [Linux Media]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux