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>

diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index 759d8f4..86fd21e 100644 (file)
--- 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 435cc4d..67d9642 100644 (file)
--- 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)