Re: [PATCH v6 05/14] mmc: sdhci-msm: Update DLL reset sequence

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Hi Stephen,

On 11/9/2016 4:36 AM, Stephen Boyd wrote:
On 11/07, Ritesh Harjani wrote:

diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
index 42f42aa..32b0b79 100644
--- a/drivers/mmc/host/sdhci-msm.c
+++ b/drivers/mmc/host/sdhci-msm.c
@@ -58,11 +58,17 @@
 #define CORE_DLL_CONFIG		0x100
 #define CORE_DLL_STATUS		0x108

+#define CORE_DLL_CONFIG_2	0x1b4
+#define CORE_FLL_CYCLE_CNT	BIT(18)
+#define CORE_DLL_CLOCK_DISABLE	BIT(21)
+
 #define CORE_VENDOR_SPEC	0x10c
 #define CORE_CLK_PWRSAVE	BIT(1)

 #define CORE_VENDOR_SPEC_CAPABILITIES0	0x11c

+#define TCXO_FREQ		19200000

TCXO_FREQ could change based on the board. For example, IPQ has
it as 25 MHz.
Actually not sure of the proper way on how to get this freq in driver
today. We may use xo_board clock but, it is not available for all boards
except 8996/8916 I guess.

Also, there is no sdhc for IPQ board and for all other boards TCXO_FREQ is same where sdhci-msm driver is used. For that purpose this was defined here for sdhci-msm driver.

Do you think in that case we should keep it this way for now and later change if a need arise to change the TCXO_FREQ ?


+
 #define CDR_SELEXT_SHIFT	20
 #define CDR_SELEXT_MASK		(0xf << CDR_SELEXT_SHIFT)
 #define CMUX_SHIFT_PHASE_SHIFT	24
@@ -330,6 +349,24 @@ static int msm_init_cm_dll(struct sdhci_host *host)
 	writel_relaxed(config, host->ioaddr + CORE_DLL_CONFIG);
 	msm_cm_dll_set_freq(host);

+	if (msm_host->use_14lpp_dll_reset) {
+		u32 mclk_freq = 0;
+
+		if ((readl_relaxed(host->ioaddr + CORE_DLL_CONFIG_2)
+					& CORE_FLL_CYCLE_CNT))

I suggest you grow a local variable.
Ok.


+			mclk_freq = (u32)((host->clock / TCXO_FREQ) * 8);

Is the cast necessary?
Will remove it.


+		else
+			mclk_freq = (u32)((host->clock / TCXO_FREQ) * 4);

Ditto
Will remove it.


+
+		config = readl_relaxed(host->ioaddr + CORE_DLL_CONFIG_2);
+		config &= ~(0xFF << 10);
+		config |= mclk_freq << 10;
+
+		writel_relaxed(config, host->ioaddr + CORE_DLL_CONFIG_2);
+		/* wait for 5us before enabling DLL clock */

Usually there's a barrier between writel_relaxed() and delay
because we don't know when the writel will be posted out and the
delay is there to wait for the operation to happen. Probably
should change this to be a writel() instead.

Arnd, already explained here.
We do need the udelay here as per the HW sequence itself.



+		udelay(5);
+	}
+
 	/* Write 0 to DLL_RST bit of DLL_CONFIG register */
 	config = readl_relaxed(host->ioaddr + CORE_DLL_CONFIG);
 	config &= ~CORE_DLL_RST;
@@ -340,6 +377,14 @@ static int msm_init_cm_dll(struct sdhci_host *host)
 	config &= ~CORE_DLL_PDN;
 	writel_relaxed(config, host->ioaddr + CORE_DLL_CONFIG);

+	if (msm_host->use_14lpp_dll_reset) {
+		msm_cm_dll_set_freq(host);
+		/* Enable the DLL clock */
+		config = readl_relaxed(host->ioaddr + CORE_DLL_CONFIG_2);
+		config &= ~CORE_DLL_CLOCK_DISABLE;
+		writel_relaxed(config, host->ioaddr + CORE_DLL_CONFIG_2);
+	}
+
 	/* Set DLL_EN bit to 1. */
 	config = readl_relaxed(host->ioaddr + CORE_DLL_CONFIG);
 	config |= CORE_DLL_EN;
@@ -641,6 +686,9 @@ static int sdhci_msm_probe(struct platform_device *pdev)
 	dev_dbg(&pdev->dev, "MCI Version: 0x%08x, major: 0x%04x, minor: 0x%02x\n",
 		core_version, core_major, core_minor);

+	if ((core_major == 1) && (core_minor >= 0x42))

Why so many parenthesis?
Sure, will remove it.


+		msm_host->use_14lpp_dll_reset = true;
+
 	/*


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