linux-kernel - [PATCH 2/2] mmc: tegra: Implement periodic pad calibration

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Date:   Mon, 20 Aug 2018 12:23:33 +0300
From:   Aapo Vienamo <avienamo@...dia.com>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        "Jonathan Hunter" <jonathanh@...dia.com>
CC:     <linux-mmc@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Aapo Vienamo <avienamo@...dia.com>
Subject: [PATCH 2/2] mmc: tegra: Implement periodic pad calibration

Rerun the pad calibration procedure before sdhci_request() if
the 100 ms recalibration interval has been exceeded.

Signed-off-by: Aapo Vienamo <avienamo@...dia.com>
---
 drivers/mmc/host/sdhci-tegra.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index 94624ec..ef18a0c 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -30,6 +30,7 @@
 #include <linux/mmc/mmc.h>
 #include <linux/mmc/slot-gpio.h>
 #include <linux/gpio/consumer.h>
+#include <linux/ktime.h>
 
 #include "sdhci-pltfm.h"
 
@@ -122,6 +123,7 @@ struct sdhci_tegra {
 	struct pinctrl_state *pinctrl_state_1v8;
 
 	struct sdhci_tegra_autocal_offsets autocal_offsets;
+	ktime_t last_calib;
 
 	u32 default_tap;
 	u32 default_trim;
@@ -533,6 +535,22 @@ static void tegra_sdhci_parse_pad_autocal_dt(struct sdhci_host *host)
 		autocal->pull_down_hs400 = autocal->pull_down_1v8;
 }
 
+static void tegra_sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_tegra *tegra_host = sdhci_pltfm_priv(pltfm_host);
+	ktime_t since_calib = ktime_sub(ktime_get(), tegra_host->last_calib);
+
+	/* 100 ms calibration interval is specified in the TRM */
+	if (ktime_to_ms(since_calib) > 100) {
+		tegra_sdhci_pad_autocalib(host);
+		tegra_host->last_calib = ktime_get();
+	}
+
+	sdhci_request(mmc, mrq);
+}
+
 static void tegra_sdhci_parse_tap_and_trim(struct sdhci_host *host)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -1014,6 +1032,10 @@ static int sdhci_tegra_probe(struct platform_device *pdev)
 				sdhci_tegra_start_signal_voltage_switch;
 	}
 
+	/* Hook to periodically rerun pad calibration */
+	if (soc_data->nvquirks & NVQUIRK_HAS_PADCALIB)
+		host->mmc_host_ops.request = tegra_sdhci_request;
+
 	host->mmc_host_ops.hs400_enhanced_strobe =
 			tegra_sdhci_hs400_enhanced_strobe;
 
-- 
2.7.4