Re: [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@xxxxxxxxxx wrote:
> On Tue, Feb 15, 2022 at 8:06 PM Vinod Koul <vkoul@xxxxxxxxxx> 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@xxxxxxxxxx>
> > > ---
> > >  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@xxxxxxxxxxxx>

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