mmc: tmio: fix a deadlock

Currently the tmio-mmc driver contains a recursive runtime PM method
invocation, which leads to a deadlock on a mutex. Avoid it by taking
care not to request DMA too early.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
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 ba0d8e6..087d880 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -109,6 +109,7 @@
 
 #if defined(CONFIG_MMC_SDHI) || defined(CONFIG_MMC_SDHI_MODULE)
 void tmio_mmc_start_dma(struct tmio_mmc_host *host, struct mmc_data *data);
+void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable);
 void tmio_mmc_request_dma(struct tmio_mmc_host *host, struct tmio_mmc_data *pdata);
 void tmio_mmc_release_dma(struct tmio_mmc_host *host);
 #else
@@ -117,6 +118,10 @@
 {
 }
 
+static inline void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
+{
+}
+
 static inline void tmio_mmc_request_dma(struct tmio_mmc_host *host,
 				 struct tmio_mmc_data *pdata)
 {