linux-kernel - [PATCH 1/2] mmc: sdhci: Add PLL Enable support to internal clock setup

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Message-ID: <20190717023951.5064-1-ben.chuang@genesyslogic.com.tw>
Date:   Wed, 17 Jul 2019 10:39:51 +0800
From:   Ben Chuang <ben.chuang@...esyslogic.com.tw>
To:     <adrian.hunter@...el.com>, <ulf.hansson@...aro.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>,
        <johnsonm@...lj.org>, Ben Chuang <ben.chuang@...esyslogic.com.tw>
Subject: [PATCH 1/2] mmc: sdhci: Add PLL Enable support to internal clock setup

The GL9750 and GL9755 chipsets, and possibly others, require PLL Enable
setup as part of the internal clock setup as described in 3.2.1 Internal
Clock Setup Sequence of SD Host Controller Simplified Specification
Version 4.20.  This changes the timeouts to the new specification of
150ms for each step and is documented as safe for "prior versions which
do not support PLL Enable."

Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
Co-developed-by: Michael K Johnson <johnsonm@...lj.org>
Signed-off-by: Michael K Johnson <johnsonm@...lj.org>
---
 drivers/mmc/host/sdhci.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 59acf8e3331e..fd684d7a5f15 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1636,15 +1636,11 @@ void sdhci_enable_clk(struct sdhci_host *host, u16 clk)
        clk |= SDHCI_CLOCK_INT_EN;
        sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);

-       /* Wait max 20 ms */
-       timeout = ktime_add_ms(ktime_get(), 20);
-       while (1) {
-               bool timedout = ktime_after(ktime_get(), timeout);
-
-               clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
-               if (clk & SDHCI_CLOCK_INT_STABLE)
-                       break;
-               if (timedout) {
+       /* Wait max 150 ms */
+       timeout = ktime_add_ms(ktime_get(), 150);
+       while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
+               & SDHCI_CLOCK_INT_STABLE)) {
+               if (ktime_after(ktime_get(), timeout)) {
                        pr_err("%s: Internal clock never stabilised.\n",
                               mmc_hostname(host->mmc));
                        sdhci_dumpregs(host);
@@ -1653,8 +1649,27 @@ void sdhci_enable_clk(struct sdhci_host *host, u16 clk)
                udelay(10);
        }

+       clk |= SDHCI_CLOCK_PLL_EN;
+       clk &= ~SDHCI_CLOCK_INT_STABLE;
+       sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+       /* Wait max 150 ms */
+       timeout = ktime_add_ms(ktime_get(), 150);
+       while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
+               & SDHCI_CLOCK_INT_STABLE)) {
+               if (ktime_after(ktime_get(), timeout)) {
+                       pr_err("%s: PLL clock never stabilised.\n",
+                              mmc_hostname(host->mmc));
+                       sdhci_dumpregs(host);
+                       return;
+               }
+               udelay(10);
+       }
+
        clk |= SDHCI_CLOCK_CARD_EN;
        sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+       mdelay(1);
 }
 EXPORT_SYMBOL_GPL(sdhci_enable_clk);

--
2.22.0

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