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

> 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.

Are you sure? It's the first time I hear about it.
Could anybody confirm?

>> };
>>
>> 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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