dmaengine: bcm2835: Drop gratuitous list deletion [Linux 5.1]

dmaengine: bcm2835: Drop gratuitous list deletion [Linux 5.1]

This Linux kernel change "dmaengine: bcm2835: Drop gratuitous list deletion" is included in the Linux 5.1 release. This change is authored by Lukas Wunner <lukas [at] wunner.de> on Wed Jan 23 09:26:00 2019 +0100. The commit for this change in Linux stable tree is efdffc1 (patch).

dmaengine: bcm2835: Drop gratuitous list deletion

The BCM2835 DMA driver deletes a channel from a list upon termination
without having added it to a list first.  Moreover that operation is
protected by a spinlock which isn't taken anywhere else.  These appear
to be remnants of an older version of the driver which accidentally
got mainlined.  Remove the dead code.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Frank Pavlic <f.pavlic@kunbus.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Florian Meier <florian.meier@koalo.de>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Acked-by: Florian Kauer <florian.kauer@koalo.de>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

There are 10 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/dma/bcm2835-dma.c | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
index 6d66e23..138bda3 100644
--- a/drivers/dma/bcm2835-dma.c
+++ b/drivers/dma/bcm2835-dma.c
@@ -42,7 +42,6 @@

 struct bcm2835_dmadev {
    struct dma_device ddev;
-   spinlock_t lock;
    void __iomem *base;
    struct device_dma_parameters dma_parms;
 };
@@ -64,7 +63,6 @@ struct bcm2835_cb_entry {

 struct bcm2835_chan {
    struct virt_dma_chan vc;
-   struct list_head node;

    struct dma_slave_config cfg;
    unsigned int dreq;
@@ -777,17 +775,11 @@ static int bcm2835_dma_slave_config(struct dma_chan *chan,
 static int bcm2835_dma_terminate_all(struct dma_chan *chan)
 {
    struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
-   struct bcm2835_dmadev *d = to_bcm2835_dma_dev(c->vc.chan.device);
    unsigned long flags;
    LIST_HEAD(head);

    spin_lock_irqsave(&c->vc.lock, flags);

-   /* Prevent this channel being scheduled */
-   spin_lock(&d->lock);
-   list_del_init(&c->node);
-   spin_unlock(&d->lock);
-
    /* stop DMA activity */
    if (c->desc) {
        vchan_terminate_vdesc(&c->desc->vd);
@@ -820,7 +812,6 @@ static int bcm2835_dma_chan_init(struct bcm2835_dmadev *d, int chan_id,

    c->vc.desc_free = bcm2835_dma_desc_free;
    vchan_init(&c->vc, &d->ddev);
-   INIT_LIST_HEAD(&c->node);

    c->chan_base = BCM2835_DMA_CHANIO(d->base, chan_id);
    c->ch = chan_id;
@@ -923,7 +914,6 @@ static int bcm2835_dma_probe(struct platform_device *pdev)
    od->ddev.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
    od->ddev.dev = &pdev->dev;
    INIT_LIST_HEAD(&od->ddev.channels);
-   spin_lock_init(&od->lock);

    platform_set_drvdata(pdev, od);

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