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SubjectRe: [PATCH 01/14] dmaengine: dma-jz4780: Avoid hardcoding number of channels
Hi Paul,

On 3 July 2018 at 18:02, Paul Cercueil <paul@crapouillou.net> wrote:
> As part of the work to support various other Ingenic JZ47xx SoC versions,
> which don't feature the same number of DMA channels per core, we now
> deduce the number of DMA channels available from the devicetree
> compatible string.
>
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
> drivers/dma/dma-jz4780.c | 53 +++++++++++++++++++++++++++++-----------
> 1 file changed, 39 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
> index 85820a2d69d4..b40f491f0367 100644
> --- a/drivers/dma/dma-jz4780.c
> +++ b/drivers/dma/dma-jz4780.c
> @@ -16,6 +16,7 @@
> #include <linux/interrupt.h>
> #include <linux/module.h>
> #include <linux/of.h>
> +#include <linux/of_device.h>
> #include <linux/of_dma.h>
> #include <linux/platform_device.h>
> #include <linux/slab.h>
> @@ -23,8 +24,6 @@
> #include "dmaengine.h"
> #include "virt-dma.h"
>
> -#define JZ_DMA_NR_CHANNELS 32
> -
> /* Global registers. */
> #define JZ_DMA_REG_DMAC 0x1000
> #define JZ_DMA_REG_DIRQP 0x1004
> @@ -135,14 +134,20 @@ struct jz4780_dma_chan {
> unsigned int curr_hwdesc;
> };
>
> +enum jz_version {
> + ID_JZ4780,
> +};
> +
> struct jz4780_dma_dev {
> struct dma_device dma_device;
> void __iomem *base;
> struct clk *clk;
> unsigned int irq;
> + unsigned int nb_channels;
> + enum jz_version version;
>
> uint32_t chan_reserved;
> - struct jz4780_dma_chan chan[JZ_DMA_NR_CHANNELS];
> + struct jz4780_dma_chan chan[];

Looks like a variable length array in struct. I think there is some
effort to remove the usage of VLA. Can you revisit this? I may be
wrong, please feel free to correct.

> };
>
> struct jz4780_dma_filter_data {
> @@ -648,7 +653,7 @@ static irqreturn_t jz4780_dma_irq_handler(int irq, void *data)
>
> pending = jz4780_dma_readl(jzdma, JZ_DMA_REG_DIRQP);
>
> - for (i = 0; i < JZ_DMA_NR_CHANNELS; i++) {
> + for (i = 0; i < jzdma->nb_channels; i++) {
> if (!(pending & (1<<i)))
> continue;
>
> @@ -728,7 +733,7 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
> data.channel = dma_spec->args[1];
>
> if (data.channel > -1) {
> - if (data.channel >= JZ_DMA_NR_CHANNELS) {
> + if (data.channel >= jzdma->nb_channels) {
> dev_err(jzdma->dma_device.dev,
> "device requested non-existent channel %u\n",
> data.channel);
> @@ -752,19 +757,45 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
> }
> }
>
> +static const unsigned int jz4780_dma_nb_channels[] = {
> + [ID_JZ4780] = 32,
> +};
> +
> +static const struct of_device_id jz4780_dma_dt_match[] = {
> + { .compatible = "ingenic,jz4780-dma", .data = (void *)ID_JZ4780 },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, jz4780_dma_dt_match);
> +
> static int jz4780_dma_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> + const struct of_device_id *of_id = of_match_device(
> + jz4780_dma_dt_match, dev);
> struct jz4780_dma_dev *jzdma;
> struct jz4780_dma_chan *jzchan;
> struct dma_device *dd;
> struct resource *res;
> + enum jz_version version;
> + unsigned int nb_channels;
> int i, ret;
>
> - jzdma = devm_kzalloc(dev, sizeof(*jzdma), GFP_KERNEL);
> + if (of_id)
> + version = (enum jz_version)of_id->data;
> + else
> + version = ID_JZ4780; /* Default when not probed from DT */
> +
> + nb_channels = jz4780_dma_nb_channels[version];
> +
> + jzdma = devm_kzalloc(dev, sizeof(*jzdma)
> + + sizeof(*jzdma->chan) * nb_channels,
> + GFP_KERNEL);
> if (!jzdma)
> return -ENOMEM;
>
> + jzdma->nb_channels = nb_channels;
> + jzdma->version = version;
> +
> platform_set_drvdata(pdev, jzdma);
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -839,7 +870,7 @@ static int jz4780_dma_probe(struct platform_device *pdev)
>
> INIT_LIST_HEAD(&dd->channels);
>
> - for (i = 0; i < JZ_DMA_NR_CHANNELS; i++) {
> + for (i = 0; i < jzdma->nb_channels; i++) {
> jzchan = &jzdma->chan[i];
> jzchan->id = i;
>
> @@ -884,19 +915,13 @@ static int jz4780_dma_remove(struct platform_device *pdev)
>
> free_irq(jzdma->irq, jzdma);
>
> - for (i = 0; i < JZ_DMA_NR_CHANNELS; i++)
> + for (i = 0; i < jzdma->nb_channels; i++)
> tasklet_kill(&jzdma->chan[i].vchan.task);
>
> dma_async_device_unregister(&jzdma->dma_device);
> return 0;
> }
>
> -static const struct of_device_id jz4780_dma_dt_match[] = {
> - { .compatible = "ingenic,jz4780-dma", .data = NULL },
> - {},
> -};
> -MODULE_DEVICE_TABLE(of, jz4780_dma_dt_match);
> -
> static struct platform_driver jz4780_dma_driver = {
> .probe = jz4780_dma_probe,
> .remove = jz4780_dma_remove,
> --
> 2.18.0
>
>

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