Re: [PATCH v10 5/9] dmaengine: dw: dmamux: Introduce RZN1 DMA router support

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Miquel,

On Tue, Apr 12, 2022 at 9:39 PM Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> The Renesas RZN1 DMA IP is based on a DW core, with eg. an additional
> dmamux register located in the system control area which can take up to
> 32 requests (16 per DMA controller). Each DMA channel can be wired to
> two different peripherals.
>
> We need two additional information from the 'dmas' property: the channel
> (bit in the dmamux register) that must be accessed and the value of the
> mux for this channel.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Thanks for your patch!

> --- /dev/null
> +++ b/drivers/dma/dw/rzn1-dmamux.c
> @@ -0,0 +1,160 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2022 Schneider-Electric
> + * Author: Miquel Raynal <miquel.raynal@bootlin.com
> + * Based on TI crossbar driver written by Peter Ujfalusi <peter.ujfalusi@ti.com>
> + */
> +#include <linux/bitops.h>
> +#include <linux/of_device.h>
> +#include <linux/of_dma.h>
> +#include <linux/slab.h>
> +#include <linux/soc/renesas/r9a06g032-sysctrl.h>
> +#include <linux/types.h>
> +
> +#define RNZ1_DMAMUX_NCELLS 6
> +#define RZN1_DMAMUX_LINES 64
> +#define RZN1_DMAMUX_MAX_LINES 16
> +
> +struct rzn1_dmamux_data {
> +       struct dma_router dmarouter;
> +       unsigned long *used_chans;

Why a pointer?

> +static int rzn1_dmamux_probe(struct platform_device *pdev)
> +{
> +       struct device_node *mux_node = pdev->dev.of_node;
> +       const struct of_device_id *match;
> +       struct device_node *dmac_node;
> +       struct rzn1_dmamux_data *dmamux;
> +
> +       dmamux = devm_kzalloc(&pdev->dev, sizeof(*dmamux), GFP_KERNEL);
> +       if (!dmamux)
> +               return -ENOMEM;
> +
> +       dmamux->used_chans = devm_bitmap_zalloc(&pdev->dev, 2 * RZN1_DMAMUX_MAX_LINES,
> +                                               GFP_KERNEL);

... Oh, you want to allocate the bitmap separately, although you
know it's just a single long.

You might as well declare it in rzn1_dmamux_data as:

    unsigned long used_chans[BITS_TO_LONGS(2 * RZN1_DMAMUX_MAX_LINES)];

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds