[PATCH v5 3/3] dmaengine: sf-pdma: Get number of channel by device tree

[Palmer Dabbelt]

On Tue, 15 Feb 2022 22:52:14 PST (-0800), zong.li at sifive.com wrote:
> On Tue, Feb 15, 2022 at 8:06 PM Vinod Koul <vkoul at kernel.org> wrote:
>>
>> On 07-02-22, 14:30, Zong Li wrote:
>> > It currently assumes that there are always four channels, it would
>> > cause the error if there is actually less than four channels. Change
>> > that by getting number of channel from device tree.
>> >
>> > For backwards-compatibility, it uses the default value (i.e. 4) when
>> > there is no 'dma-channels' information in dts.
>> >
>> > Signed-off-by: Zong Li <zong.li at sifive.com>
>> > ---
>> >  drivers/dma/sf-pdma/sf-pdma.c | 21 ++++++++++++++-------
>> >  drivers/dma/sf-pdma/sf-pdma.h |  8 ++------
>> >  2 files changed, 16 insertions(+), 13 deletions(-)
>> >
>> > diff --git a/drivers/dma/sf-pdma/sf-pdma.c b/drivers/dma/sf-pdma/sf-pdma.c
>> > index f12606aeff87..2ae10b61dfa1 100644
>> > --- a/drivers/dma/sf-pdma/sf-pdma.c
>> > +++ b/drivers/dma/sf-pdma/sf-pdma.c
>> > @@ -482,9 +482,7 @@ static void sf_pdma_setup_chans(struct sf_pdma *pdma)
>> >  static int sf_pdma_probe(struct platform_device *pdev)
>> >  {
>> >       struct sf_pdma *pdma;
>> > -     struct sf_pdma_chan *chan;
>> >       struct resource *res;
>> > -     int len, chans;
>> >       int ret;
>> >       const enum dma_slave_buswidth widths =
>> >               DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
>> > @@ -492,13 +490,21 @@ static int sf_pdma_probe(struct platform_device *pdev)
>> >               DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
>> >               DMA_SLAVE_BUSWIDTH_64_BYTES;
>> >
>> > -     chans = PDMA_NR_CH;
>> > -     len = sizeof(*pdma) + sizeof(*chan) * chans;
>> > -     pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
>> > +     pdma = devm_kzalloc(&pdev->dev, sizeof(*pdma), GFP_KERNEL);
>> >       if (!pdma)
>> >               return -ENOMEM;
>> >
>> > -     pdma->n_chans = chans;
>> > +     ret = of_property_read_u32(pdev->dev.of_node, "dma-channels",
>> > +                                &pdma->n_chans);
>> > +     if (ret) {
>> > +             dev_notice(&pdev->dev, "set number of channels to default value: 4\n");
>>
>> This is useful for only debug i think, so dev_dbg perhaps
>>
>
> Thanks for your suggestion, let me change it in the next version.

Not sure if I'm missing something, but I don't see a v6.  I'm going to 
assume that one will be sent, but the suggested changes look minor 
enough so 

Acked-by: Palmer Dabbelt <palmer at rivosinc.com>

LMK if you guys were expecting this to go in via the RISC-V tree, 
otherwise I'll assume this aimed at the dmaengine tree.  Probably best to keep
all three together, so feel free to take the DTS updates as well -- having some
shared tag never hurts, but the DTs don't move that much so any conflicts
should be straight-forward to just fix at merge time.

Thanks!

>> > +             pdma->n_chans = PDMA_MAX_NR_CH;
>> > +     }
>> > +
>> > +     if (pdma->n_chans > PDMA_MAX_NR_CH) {
>> > +             dev_err(&pdev->dev, "the number of channels exceeds the maximum\n");
>> > +             return -EINVAL;
>> > +     }
>> >
>> >       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> >       pdma->membase = devm_ioremap_resource(&pdev->dev, res);
>> > @@ -556,7 +562,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
>> >       struct sf_pdma_chan *ch;
>> >       int i;
>> >
>> > -     for (i = 0; i < PDMA_NR_CH; i++) {
>> > +     for (i = 0; i < pdma->n_chans; i++) {
>> >               ch = &pdma->chans[i];
>> >
>> >               devm_free_irq(&pdev->dev, ch->txirq, ch);
>> > @@ -574,6 +580,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
>> >
>> >  static const struct of_device_id sf_pdma_dt_ids[] = {
>> >       { .compatible = "sifive,fu540-c000-pdma" },
>> > +     { .compatible = "sifive,pdma0" },
>> >       {},
>> >  };
>> >  MODULE_DEVICE_TABLE(of, sf_pdma_dt_ids);
>> > diff --git a/drivers/dma/sf-pdma/sf-pdma.h b/drivers/dma/sf-pdma/sf-pdma.h
>> > index 0c20167b097d..8127d792f639 100644
>> > --- a/drivers/dma/sf-pdma/sf-pdma.h
>> > +++ b/drivers/dma/sf-pdma/sf-pdma.h
>> > @@ -22,11 +22,7 @@
>> >  #include "../dmaengine.h"
>> >  #include "../virt-dma.h"
>> >
>> > -#define PDMA_NR_CH                                   4
>> > -
>> > -#if (PDMA_NR_CH != 4)
>> > -#error "Please define PDMA_NR_CH to 4"
>> > -#endif
>> > +#define PDMA_MAX_NR_CH                                       4
>> >
>> >  #define PDMA_BASE_ADDR                                       0x3000000
>> >  #define PDMA_CHAN_OFFSET                             0x1000
>> > @@ -118,7 +114,7 @@ struct sf_pdma {
>> >       void __iomem            *membase;
>> >       void __iomem            *mappedbase;
>> >       u32                     n_chans;
>> > -     struct sf_pdma_chan     chans[PDMA_NR_CH];
>> > +     struct sf_pdma_chan     chans[PDMA_MAX_NR_CH];
>>
>> why waste memory allocating max, we know number of channels in probe,
>> why not allocate runtime?
>>
>
> I kept it there because I'd like to do minimum change in this patch
> set. You're right, let me change it in the next version.
>
>> --
>> ~Vinod