mmc: tmio_mmc: Hotplug code regrouping

This patch regroups the code slightly, adds documentation and allows
the rtpm counter of MMC_CAP_NEEDS_POLL devices to reach 0 again.
Signed-off-by: NBastian Hecht <hechtb@gmail.com>
[g.liakhovetski@gmx.de: restore pm_runtime_get_noresume()]
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NChris Ball <cjb@laptop.org>

drivers/mmc/host/tmio_mmc_pio.c

@@ -800,8 +800,7 @@ static void tmio_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	} else if (ios->power_mode != MMC_POWER_UP) {
 		if (host->set_pwr && ios->power_mode == MMC_POWER_OFF)
 			host->set_pwr(host->pdev, 0);
-		if ((pdata->flags & TMIO_MMC_HAS_COLD_CD) &&
-		    pdata->power) {
+		if (pdata->power) {
 			pdata->power = false;
 			pm_runtime_put(&host->pdev->dev);
 		}
@@ -915,6 +914,23 @@ int __devinit tmio_mmc_host_probe(struct tmio_mmc_host **host,
 	if (ret < 0)
 		goto pm_disable;
 
+	/*
+	 * There are 4 different scenarios for the card detection:
+	 *  1) an external gpio irq handles the cd (best for power savings)
+	 *  2) internal sdhi irq handles the cd
+	 *  3) a worker thread polls the sdhi - indicated by MMC_CAP_NEEDS_POLL
+	 *  4) the medium is non-removable - indicated by MMC_CAP_NONREMOVABLE
+	 *
+	 *  While we increment the rtpm counter for all scenarios when the mmc
+	 *  core activates us by calling an appropriate set_ios(), we must
+	 *  additionally ensure that in case 2) the tmio mmc hardware stays
+	 *  powered on during runtime for the card detection to work.
+	 */
+	if (!(pdata->flags & TMIO_MMC_HAS_COLD_CD
+		|| mmc->caps & MMC_CAP_NEEDS_POLL
+		|| mmc->caps & MMC_CAP_NONREMOVABLE))
+		pm_runtime_get_noresume(&pdev->dev);
+
 	tmio_mmc_clk_stop(_host);
 	tmio_mmc_reset(_host);
 
@@ -933,12 +949,6 @@ int __devinit tmio_mmc_host_probe(struct tmio_mmc_host **host,
 	/* See if we also get DMA */
 	tmio_mmc_request_dma(_host, pdata);
 
-	/* We have to keep the device powered for its card detection to work */
-	if (!(pdata->flags & TMIO_MMC_HAS_COLD_CD)) {
-		pdata->power = true;
-		pm_runtime_get_noresume(&pdev->dev);
-	}
-
 	mmc_add_host(mmc);
 
 	/* Unmask the IRQs we want to know about */
@@ -974,7 +984,9 @@ void tmio_mmc_host_remove(struct tmio_mmc_host *host)
 	 * the controller, the runtime PM is suspended and pdata->power == false,
 	 * so, our .runtime_resume() will not try to detect a card in the slot.
 	 */
-	if (host->pdata->flags & TMIO_MMC_HAS_COLD_CD)
+	if (host->pdata->flags & TMIO_MMC_HAS_COLD_CD
+		|| host->mmc->caps & MMC_CAP_NEEDS_POLL
+		|| host->mmc->caps & MMC_CAP_NONREMOVABLE)
 		pm_runtime_get_sync(&pdev->dev);
 
 	mmc_remove_host(host->mmc);