openwrt/target/linux/brcm2708/patches-4.4/0400-dmaengine-bcm2835-Load-driver-early-and-support-lega.patch

From 8b8b59db27e6e1597737fbd1fd7a17216540bc38 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Sat, 3 Oct 2015 22:22:55 +0200
Subject: [PATCH] dmaengine: bcm2835: Load driver early and support legacy API
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Load driver early since at least bcm2708_fb doesn't support deferred
probing and even if it did, we don't want the video driver deferred.

Support the legacy DMA API which is needed by bcm2708_fb
(but only using the dedicated dma channel 0).

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
---
 drivers/dma/Kconfig       |  2 +-
 drivers/dma/bcm2835-dma.c | 27 ++++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 2 deletions(-)

--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -108,7 +108,7 @@ config COH901318
 
 config DMA_BCM2835
 	tristate "BCM2835 DMA engine support"
-	depends on ARCH_BCM2835
+	depends on ARCH_BCM2835 || ARCH_BCM2708 || ARCH_BCM2709
 	select DMA_ENGINE
 	select DMA_VIRTUAL_CHANNELS
 
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -37,6 +37,7 @@
 #include <linux/interrupt.h>
 #include <linux/list.h>
 #include <linux/module.h>
+#include <linux/platform_data/dma-bcm2708.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/io.h>
@@ -1021,6 +1022,14 @@ static int bcm2835_dma_probe(struct plat
 
 	dev_dbg(&pdev->dev, "Load BCM2835 DMA engine driver\n");
 
+	/* load the legacy api if bit 0 in the mask is cleared */
+	if ((chans_available & BIT(0)) == 0) {
+		rc = bcm_dmaman_probe(pdev, base, BIT(0));
+		if (rc)
+			dev_err(&pdev->dev,
+				"Failed to initialize the legacy API\n");
+	}
+
 	return 0;
 
 err_no_dma:
@@ -1032,6 +1041,7 @@ static int bcm2835_dma_remove(struct pla
 {
 	struct bcm2835_dmadev *od = platform_get_drvdata(pdev);
 
+	bcm_dmaman_remove(pdev);
 	dma_async_device_unregister(&od->ddev);
 	bcm2835_dma_free(od);
 
@@ -1047,7 +1057,22 @@ static struct platform_driver bcm2835_dm
 	},
 };
 
-module_platform_driver(bcm2835_dma_driver);
+static int bcm2835_dma_init(void)
+{
+	return platform_driver_register(&bcm2835_dma_driver);
+}
+
+static void bcm2835_dma_exit(void)
+{
+	platform_driver_unregister(&bcm2835_dma_driver);
+}
+
+/*
+ * Load after serial driver (arch_initcall) so we see the messages if it fails,
+ * but before drivers (module_init) that need a DMA channel.
+ */
+subsys_initcall(bcm2835_dma_init);
+module_exit(bcm2835_dma_exit);
 
 MODULE_ALIAS("platform:bcm2835-dma");
 MODULE_DESCRIPTION("BCM2835 DMA engine driver");