ENGR00227835 imx6q: gpmi: fix the warning when no NAND chip exits

If there is no nand chip in the board, the kernel will prints out the
following warning message:

------------[ cut here ]------------
WARNING: at arch/arm/plat-mxc/clock.c:63 clk_disable+0x48/0x90()
clock enable/disable mismatch! clk  apbh_dma_clk
Modules linked in:
[<80044f48>] (unwind_backtrace+0x0/0xfc) from
				[<80070ac0>] (warn_slowpath_common+0x4c/0x64)
[<80070ac0>] (warn_slowpath_common+0x4c/0x64) from
				[<80070b6c>] (warn_slowpath_fmt+0x30/0x40)
[<80070b6c>] (warn_slowpath_fmt+0x30/0x40) from
				[<8005ee60>] (clk_disable+0x48/0x90)
[<8005ee60>] (clk_disable+0x48/0x90) from
				[<80255e48>] (dma_chan_put+0x4c/0x50)
[<80255e48>] (dma_chan_put+0x4c/0x50) from
				[<80255f18>] (dma_release_channel+0x24/0x94)
[<80255f18>] (dma_release_channel+0x24/0x94) from
				[<802ad8ec>] (release_resources+0x58/0x6c)
[<802ad8ec>] (release_resources+0x58/0x6c) from
				[<80445964>] (gpmi_nand_probe+0x44c/0x4ec)
[<80445964>] (gpmi_nand_probe+0x44c/0x4ec) from
				[<80281868>] (platform_drv_probe+0x18/0x1c)
[<80281868>] (platform_drv_probe+0x18/0x1c) from
				[<80280590>] (driver_probe_device+0x98/0x1a4)
[<80280590>] (driver_probe_device+0x98/0x1a4) from
				[<80280728>] (__driver_attach+0x8c/0x90)
[<80280728>] (__driver_attach+0x8c/0x90) from
				[<8027fdd0>] (bus_for_each_dev+0x60/0x8c)
[<8027fdd0>] (bus_for_each_dev+0x60/0x8c) from
				[<8027f75c>] (bus_add_driver+0x184/0x25c)
[<8027f75c>] (bus_add_driver+0x184/0x25c) from
				[<80280d1c>] (driver_register+0x78/0x13c)
[<80280d1c>] (driver_register+0x78/0x13c) from
				[<80022d80>] (gpmi_nand_init+0xc/0x3c)
[<80022d80>] (gpmi_nand_init+0xc/0x3c) from
				[<80039478>] (do_one_initcall+0x30/0x16c)
[<80039478>] (do_one_initcall+0x30/0x16c) from
				[<80008410>] (kernel_init+0x98/0x144)
[<80008410>] (kernel_init+0x98/0x144) from
				[<8003ffb4>] (kernel_thread_exit+0x0/0x8)
---[ end trace c28d32057fe33a29 ]---

This mxs_dma_clk's usecount is not correctly changed which causes the kernel
shows this warning.

This patch adds proper clk_disable_unprepare/clk_prepare_enable in
the mxs-dma driver to balance the mxs_dma_clk's usecount.
Also put the mxs_dma_clk when the gpmi exits.

Signed-off-by: Huang Shijie <b32955@freescale.com>

4 files changed, 11 insertions, 1 deletions

diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index 162e6c3eb64d..e604cd7ae384 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c
@@ -323,6 +323,7 @@ static int mxs_dma_alloc_chan_resources(struct dma_chan *chan)
 	/* the descriptor is ready */
 	async_tx_ack(&mxs_chan->desc);
 
+	clk_disable_unprepare(mxs_dma->clk);
 	return 0;
 
 err_clk:
@@ -339,6 +340,7 @@ static void mxs_dma_free_chan_resources(struct dma_chan *chan)
 	struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
 	struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
 
+	clk_prepare_enable(mxs_dma->clk);
 	mxs_dma_disable_chan(mxs_chan);
 
 	free_irq(mxs_chan->chan_irq, mxs_dma);
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index 01c81faffa4a..2138dcb4f8a4 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
@@ -44,7 +44,7 @@ struct timing_threshod timing_default_threshold = {
 	.max_dll_delay_in_ns         = 16,
 };
 
-static struct clk *mxs_dma_clk;
+struct clk *mxs_dma_clk;
 
 static void setup_ddr_timing_onfi(struct gpmi_nand_data *this)
 {
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
index cc353ce5ae7e..9bd09fc490e5 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -439,6 +439,12 @@ static bool gpmi_dma_filter(struct dma_chan *chan, void *param)
 static void release_dma_channels(struct gpmi_nand_data *this)
 {
 	unsigned int i;
+
+	if (mxs_dma_clk) {
+		clk_put(mxs_dma_clk);
+		mxs_dma_clk = NULL;
+	}
+
 	for (i = 0; i < DMA_CHANS; i++)
 		if (this->dma_chans[i]) {
 			dma_release_channel(this->dma_chans[i]);
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index 21e1f6569211..77d0d273a297 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -290,4 +290,6 @@ extern int gpmi_read_page(struct gpmi_nand_data *,
 #define GPMI_IS_MX23(x)		((x)->pdev->id_entry->driver_data == IS_MX23)
 #define GPMI_IS_MX28(x)		((x)->pdev->id_entry->driver_data == IS_MX28)
 #define GPMI_IS_MX6Q(x)		((x)->pdev->id_entry->driver_data == IS_MX6Q)
+
+extern struct clk *mxs_dma_clk;
 #endif