mtd: ams-delta: fix request_mem_region() failure

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=b027274d2e3a332683b73f15e5cea79c240bc9a3
Commit:     b027274d2e3a332683b73f15e5cea79c240bc9a3
Parent:     226bb7df3d22bcf4a1c0fe8206c80cc427498eae
Author:     Janusz Krzysztofik <jkrzyszt at tis.icnet.pl>
AuthorDate: Mon May 7 22:51:37 2012 +0200
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Tue May 8 16:24:33 2012 -0500

    mtd: ams-delta: fix request_mem_region() failure
    
    A call to request_mem_region() has been introduced in the omap-gpio
    driver recently (commit 96751fcbe5438e95514b025e9cee7a6d38038f40,
    "gpio/omap: Use devm_ API and add request_mem_region"). This change
    prevented the Amstrad Delta NAND driver, which was doing the same in
    order to take control over OMAP MPU I/O lines that the NAND device hangs
    off, from loading successfully.
    
    The I/O lines and corresponding registers used by the NAND driver are a
    subset of those used for the GPIO function. Then, to avoid run time
    collisions, all MPUIO GPIO lines should be marked as requested while
    initializing the NAND driver, and vice versa, a single MPUIO GPIO line
    already requested before the NAND driver initialization is attempted
    should prevent the NAND device from being started successfully.
    
    There is another driver, omap-keypad, which also manipulates MPUIO
    registers, but has never been calling request_mem_region() on startup,
    so it's not affected by the change in the gpio-omap and works correctly.
    It uses the depreciated omap_read/write functions for accessing MPUIO
    registers. Unlike the NAND driver, these I/O lines and registers are
    separate from those used by the GPIO driver. However, both register sets
    are non-contiguous and overlapping, so it would be impractical to
    request the two sets separately, one from the gpio-omap, the other form
    the omap-keypad driver.
    
    In order to solve all these issues correctly, a solution first suggested
    by Artem Bityutskiy, then closer specified by Tony Lindgren while they
    commented the initial version of this fix, should be implemented. The
    gpio-omap driver should export a few functions which would allow the
    other two drivers to access MPUIO registers in a safe manner instead of
    trying to manage them in parallel to the GPIO driver.  However, such a
    big change, affecting 3 drivers all together, is not suitable for the rc
    cycle, and should be prepared for the merge window.  Then, an
    alternative solution is proposed as a regression fix.
    
    For the ams-delta NAND driver to initialize correctly in coexistence
    with the changed GPIO driver, drop the request_mem_region() call from
    the former, especially as this call is going to be removed while the
    long-term solution is implemented.
    
    Tested on Amstrad Delta.
    
    Signed-off-by: Janusz Krzysztofik <jkrzyszt at tis.icnet.pl>
    Acked-by: Tony Lindgren <tony at atomide.com>
    Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/nand/ams-delta.c |   17 ++++++-----------
 1 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/mtd/nand/ams-delta.c b/drivers/mtd/nand/ams-delta.c
index 7341695..861ca8f 100644
--- a/drivers/mtd/nand/ams-delta.c
+++ b/drivers/mtd/nand/ams-delta.c
@@ -212,18 +212,17 @@ static int __devinit ams_delta_init(struct platform_device *pdev)
 	/* Link the private data with the MTD structure */
 	ams_delta_mtd->priv = this;
 
-	if (!request_mem_region(res->start, resource_size(res),
-			dev_name(&pdev->dev))) {
-		dev_err(&pdev->dev, "request_mem_region failed\n");
-		err = -EBUSY;
-		goto out_free;
-	}
+	/*
+	 * Don't try to request the memory region from here,
+	 * it should have been already requested from the
+	 * gpio-omap driver and requesting it again would fail.
+	 */
 
 	io_base = ioremap(res->start, resource_size(res));
 	if (io_base == NULL) {
 		dev_err(&pdev->dev, "ioremap failed\n");
 		err = -EIO;
-		goto out_release_io;
+		goto out_free;
 	}
 
 	this->priv = io_base;
@@ -271,8 +270,6 @@ out_gpio:
 	platform_set_drvdata(pdev, NULL);
 	gpio_free(AMS_DELTA_GPIO_PIN_NAND_RB);
 	iounmap(io_base);
-out_release_io:
-	release_mem_region(res->start, resource_size(res));
 out_free:
 	kfree(ams_delta_mtd);
  out:
@@ -285,7 +282,6 @@ out_free:
 static int __devexit ams_delta_cleanup(struct platform_device *pdev)
 {
 	void __iomem *io_base = platform_get_drvdata(pdev);
-	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
 	/* Release resources, unregister device */
 	nand_release(ams_delta_mtd);
@@ -293,7 +289,6 @@ static int __devexit ams_delta_cleanup(struct platform_device *pdev)
 	gpio_free_array(_mandatory_gpio, ARRAY_SIZE(_mandatory_gpio));
 	gpio_free(AMS_DELTA_GPIO_PIN_NAND_RB);
 	iounmap(io_base);
-	release_mem_region(res->start, resource_size(res));
 
 	/* Free the MTD device structure */
 	kfree(ams_delta_mtd);