On 22-12-18, 08:28, Lukas Wunner wrote:
> 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.
>
> While at it remove an outdated comment claiming the driver only supports
Ditto, whenever you use also, while at it... think if this is a
candidate for splitting up.
A patch should do one thing only..
> cyclic transactions. The driver has been supporting other transaction
> types for more than two years.
>
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
> Cc: Frank Pavlic <f.pavlic@xxxxxxxxx>
> Cc: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
> Cc: Florian Meier <florian.meier@xxxxxxxx>
> ---
> drivers/dma/bcm2835-dma.c | 13 -------------
> 1 file changed, 13 deletions(-)
>
> diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> index e424e232a3d0..633be2ee7f33 100644
> --- a/drivers/dma/bcm2835-dma.c
> +++ b/drivers/dma/bcm2835-dma.c
> @@ -2,9 +2,6 @@
> /*
> * BCM2835 DMA engine support
> *
> - * This driver only supports cyclic DMA transfers
> - * as needed for the I2S module.
> - *
> * Author: Florian Meier <florian.meier@xxxxxxxx>
> * Copyright 2013
> *
> @@ -42,7 +39,6 @@
>
> struct bcm2835_dmadev {
> struct dma_device ddev;
> - spinlock_t lock;
> void __iomem *base;
> struct device_dma_parameters dma_parms;
> };
> @@ -64,7 +60,6 @@ struct bcm2835_cb_entry {
>
> struct bcm2835_chan {
> struct virt_dma_chan vc;
> - struct list_head node;
>
> struct dma_slave_config cfg;
> unsigned int dreq;
> @@ -772,17 +767,11 @@ 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);
> @@ -815,7 +804,6 @@ 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;
> @@ -918,7 +906,6 @@ 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);
>
> --
> 2.19.2
--
~Vinod
