RE: [PATCH v3 2/4] drivers: dma: sh: Add DMAC driver for RZ/G2L SoC

[Biju Das <biju.das.jz@bp.renesas.com>]

Hi Geert,

Thanks for the feedback.

> Subject: Re: [PATCH v3 2/4] drivers: dma: sh: Add DMAC driver for RZ/G2L
> SoC
> 
> Hi Biju,
> 
> On Fri, Jul 2, 2021 at 12:05 PM Biju Das <biju.das.jz@bp.renesas.com>
> wrote:
> > Add DMA Controller driver for RZ/G2L SoC.
> >
> > Based on the work done by Chris Brandt for RZ/A DMA driver.
> >
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> > Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> 
> Thanks for your patch!
> 
> > --- /dev/null
> > +++ b/drivers/dma/sh/rz-dmac.c
> 
> > +static void rz_dmac_set_dmars_register(struct rz_dmac *dmac, int nr,
> > +                                      u32 dmars) {
> > +       u32 dmars_offset = (nr / 2) * 4;
> > +       u32 dmars32;
> > +
> > +       dmars32 = rz_dmac_ext_readl(dmac, dmars_offset);
> > +       if (nr % 2) {
> > +               dmars32 &= 0x0000ffff;
> > +               dmars32 |= dmars << 16;
> > +       } else {
> > +               dmars32 &= 0xffff0000;
> > +               dmars32 |= dmars;
> > +       }
> 
> An alternative to Vinod's suggestion:
> 
>     shift = (nr %2) * 16;
>     dmars32 &= ~(0xffff << shift);
>     dmars32 |= dmars << shift;
> 

OK.

> > +
> > +       rz_dmac_ext_writel(dmac, dmars32, dmars_offset); }
> 
> > +static int rz_dmac_chan_probe(struct rz_dmac *dmac,
> > +                             struct rz_dmac_chan *channel,
> > +                             unsigned int index) {
> > +       struct platform_device *pdev = to_platform_device(dmac->dev);
> > +       struct rz_lmdesc *lmdesc;
> > +       char pdev_irqname[5];
> > +       char *irqname;
> > +       int ret;
> > +
> > +       channel->index = index;
> > +       channel->mid_rid = -EINVAL;
> > +
> > +       /* Request the channel interrupt. */
> > +       sprintf(pdev_irqname, "ch%u", index);
> > +       channel->irq = platform_get_irq_byname(pdev, pdev_irqname);
> > +       if (channel->irq < 0)
> > +               return -ENODEV;
> 
> Please propagate the error in channel->irq, which might be -EPROBE_DEFER.
OK.

> 
> > +static int rz_dmac_parse_of(struct device *dev, struct rz_dmac *dmac)
> > +{
> > +       struct device_node *np = dev->of_node;
> > +       int ret;
> > +
> > +       ret = of_property_read_u32(np, "dma-channels", &dmac-
> >n_channels);
> > +       if (ret < 0) {
> > +               dev_err(dev, "unable to read dma-channels property\n");
> > +               return ret;
> > +       }
> > +
> > +       if (!dmac->n_channels || dmac->n_channels >
> RZ_DMAC_MAX_CHANNELS) {
> > +               dev_err(dev, "invalid number of channels %u\n", dmac-
> >n_channels);
> > +               return -EINVAL;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static int rz_dmac_probe(struct platform_device *pdev) {
> > +       const char *irqname = "error";
> > +       struct dma_device *engine;
> > +       struct rz_dmac *dmac;
> > +       int channel_num;
> > +       int ret, i;
> 
> unsigned int i;

OK.

> 
> > +       int irq;
> > +
> > +       dmac = devm_kzalloc(&pdev->dev, sizeof(*dmac), GFP_KERNEL);
> > +       if (!dmac)
> > +               return -ENOMEM;
> > +
> > +       dmac->dev = &pdev->dev;
> > +       platform_set_drvdata(pdev, dmac);
> > +
> > +       ret = rz_dmac_parse_of(&pdev->dev, dmac);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       dmac->channels = devm_kcalloc(&pdev->dev, dmac->n_channels,
> > +                                     sizeof(*dmac->channels),
> GFP_KERNEL);
> > +       if (!dmac->channels)
> > +               return -ENOMEM;
> > +
> > +       /* Request resources */
> > +       dmac->base = devm_platform_ioremap_resource(pdev, 0);
> > +       if (IS_ERR(dmac->base))
> > +               return PTR_ERR(dmac->base);
> > +
> > +       dmac->ext_base = devm_platform_ioremap_resource(pdev, 1);
> > +       if (IS_ERR(dmac->ext_base))
> > +               return PTR_ERR(dmac->ext_base);
> > +
> > +       /* Register interrupt handler for error */
> > +       irq = platform_get_irq_byname(pdev, irqname);
> > +       if (irq < 0) {
> > +               dev_err(&pdev->dev, "no error IRQ specified\n");
> > +               return -ENODEV;
> 
> I'd say "return dev_err_probe(&pdev->dev, irq, ..);", but
> platform_get_irq_byname() already prints an error message, so please just
> use "return irq;" to propagate the error, which could be -EPROBE_DEFER.

OK. Will just return irq;

> 
> > +       }
> 
> > +static int rz_dmac_remove(struct platform_device *pdev) {
> > +       struct rz_dmac *dmac = platform_get_drvdata(pdev);
> > +       int i;
> 
> unsigned int i;

OK.

Regards,
Biju