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

[Aapo Vienamo]

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

Signed-off-by: Aapo Vienamo <avien...@nvidia.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