mmc: tmio: fix unbalanced power-on calls with clock-gating enabled

With MMC clock gating enabled the MMC core currently calls MMC host driver's
.set_ios() method with .power_mode == MMC_POWER_ON and the clock value set
either to 0 or to the target rate. The tmio MMC driver then wrongly
translates the latter calls to card slot power-on requests, even when the
slot already was on. This patch fixes the driver to avoid needlessly
incrementing power-supplying regulator's use count.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 35 insertions, 12 deletions

diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index 759d8f4f130c..86fd21e00099 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -40,6 +40,22 @@
 
 struct tmio_mmc_data;
 
+/*
+ * We differentiate between the following 3 power states:
+ * 1. card slot powered off, controller stopped. This is used, when either there
+ *    is no card in the slot, or the card really has to be powered down.
+ * 2. card slot powered on, controller stopped. This is used, when a card is in
+ *    the slot, but no activity is currently taking place. This is a power-
+ *    saving mode with card-state preserved. This state can be entered, e.g.
+ *    when MMC clock-gating is used.
+ * 3. card slot powered on, controller running. This is the actual active state.
+ */
+enum tmio_mmc_power {
+        TMIO_MMC_OFF_STOP,      /* card power off, controller stopped */
+        TMIO_MMC_ON_STOP,       /* card power on, controller stopped */
+        TMIO_MMC_ON_RUN,        /* card power on, controller running */
+};
+
 struct tmio_mmc_host {
         void __iomem *ctl;
         unsigned long bus_shift;
@@ -48,8 +64,8 @@ struct tmio_mmc_host {
         struct mmc_data         *data;
         struct mmc_host         *mmc;
 
-        /* Controller power state */
-        bool                    power;
+        /* Controller and card power state */
+        enum tmio_mmc_power     power;
 
         /* Callbacks for clock / power control */
         void (*set_pwr)(struct platform_device *host, int state);
diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
index 435cc4d2520f..67d96428e62a 100644
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -859,7 +859,7 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
          * is kept positive, so no suspending actually takes place.
          */
         if (ios->power_mode == MMC_POWER_ON && ios->clock) {
-                if (!host->power) {
+                if (host->power != TMIO_MMC_ON_RUN) {
                         tmio_mmc_clk_update(mmc);
                         pm_runtime_get_sync(dev);
                         if (host->resuming) {
@@ -868,27 +868,34 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                         }
                 }
                 tmio_mmc_set_clock(host, ios->clock);
-                if (!host->power) {
+                if (host->power == TMIO_MMC_OFF_STOP)
                         /* power up SD card and the bus */
                         tmio_mmc_power_on(host, ios->vdd);
-                        host->power = true;
-                }
+                host->power = TMIO_MMC_ON_RUN;
                 /* start bus clock */
                 tmio_mmc_clk_start(host);
         } else if (ios->power_mode != MMC_POWER_UP) {
-                if (host->power) {
-                        struct tmio_mmc_data *pdata = host->pdata;
-                        if (ios->power_mode == MMC_POWER_OFF)
+                struct tmio_mmc_data *pdata = host->pdata;
+                unsigned int old_power = host->power;
+
+                if (old_power != TMIO_MMC_OFF_STOP) {
+                        if (ios->power_mode == MMC_POWER_OFF) {
                                 tmio_mmc_power_off(host);
+                                host->power = TMIO_MMC_OFF_STOP;
+                        } else {
+                                host->power = TMIO_MMC_ON_STOP;
+                        }
+                }
+
+                if (old_power == TMIO_MMC_ON_RUN) {
                         tmio_mmc_clk_stop(host);
-                        host->power = false;
                         pm_runtime_put(dev);
                         if (pdata->clk_disable)
                                 pdata->clk_disable(host->pdev);
                 }
         }
 
-        if (host->power) {
+        if (host->power != TMIO_MMC_OFF_STOP) {
                 switch (ios->bus_width) {
                 case MMC_BUS_WIDTH_1:
                         sd_ctrl_write16(host, CTL_SD_MEM_CARD_OPT, 0x80e0);
@@ -1029,7 +1036,7 @@ int tmio_mmc_host_probe(struct tmio_mmc_host **host,
                                   mmc->caps & MMC_CAP_NONREMOVABLE ||
                                   mmc->slot.cd_irq >= 0);
 
-        _host->power = false;
+        _host->power = TMIO_MMC_OFF_STOP;
         pm_runtime_enable(&pdev->dev);
         ret = pm_runtime_resume(&pdev->dev);
         if (ret < 0)