Re: [PATCHv2 3/4] dma: fsl_raid: keep MMIO bases as void __iomem and cast at access

[Frank Li]

On Thu, Jul 16, 2026 at 01:29:48PM -0700, Rosen Penev wrote:
> The fsl_re_ctrl and fsl_re_chan_cfg structures describe memory-mapped
> RAID Engine registers accessed only via ioread32be()/iowrite32be(), yet
> the pointers to them (re_regs in struct fsl_re_drv_private, and jrregs
> in struct fsl_re_chan) were not __iomem-qualified, so sparse emitted
> "different address spaces" warnings for every register access.
>
> Store both MMIO bases as a plain void __iomem * and derive jrregs with
> void __iomem * arithmetic from re_regs, rather than carrying typed
                                 ^ base

> register struct pointers through the driver. Each function that touches
> the registers introduces a local typed pointer (struct fsl_re_ctrl
> __iomem *ctrl) and uses ->field, which is the idiomatic kernel pattern
>  and keeps the registers' __iomem qualification intact.
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Fixes: https://lore.kernel.org/oe-kbuild-all/202008111749.yy85rFMD%25lkp@xxxxxxxxx/
> Assisted-by: opencode:hy3-free
> Signed-off-by: Rosen Penev <rosenp@xxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

>  drivers/dma/fsl_raid.c | 19 ++++++++++---------
>  drivers/dma/fsl_raid.h |  4 ++--
>  2 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/dma/fsl_raid.c b/drivers/dma/fsl_raid.c
> index 888f55b672a5..524f83faf3da 100644
> --- a/drivers/dma/fsl_raid.c
> +++ b/drivers/dma/fsl_raid.c
> @@ -657,8 +657,7 @@ static int fsl_re_chan_probe(struct platform_device *ofdev,
>  		goto err_free;
>  	}
>
> -	chan->jrregs = (struct fsl_re_chan_cfg *)((u8 *)re_priv->re_regs +
> -			off + ptr);
> +	chan->jrregs = re_priv->base + off + ptr;
>
>  	/* read irq property from dts */
>  	chan->irq = irq_of_parse_and_map(np, 0);
> @@ -746,6 +745,7 @@ static int fsl_re_chan_probe(struct platform_device *ofdev,
>  /* Probe function for RAID Engine */
>  static int fsl_re_probe(struct platform_device *ofdev)
>  {
> +	struct fsl_re_ctrl __iomem *re_regs;
>  	struct fsl_re_drv_private *re_priv;
>  	struct device_node *child;
>  	u32 off;
> @@ -764,20 +764,21 @@ static int fsl_re_probe(struct platform_device *ofdev)
>  		return -ENODEV;
>
>  	/* IOMAP the entire RAID Engine region */
> -	re_priv->re_regs = devm_ioremap(dev, res->start, resource_size(res));
> -	if (!re_priv->re_regs)
> +	re_regs = devm_ioremap(dev, res->start, resource_size(res));
> +	if (!re_regs)
>  		return -EBUSY;
> +	re_priv->base = re_regs;
>
>  	/* Program the RE mode */
> -	out_be32(&re_priv->re_regs->global_config, FSL_RE_NON_DPAA_MODE);
> +	out_be32(&re_regs->global_config, FSL_RE_NON_DPAA_MODE);
>
>  	/* Program Galois Field polynomial */
> -	out_be32(&re_priv->re_regs->galois_field_config, FSL_RE_GFM_POLY);
> +	out_be32(&re_regs->galois_field_config, FSL_RE_GFM_POLY);
>
>  	dev_info(dev, "version %x, mode %x, gfp %x\n",
> -		 in_be32(&re_priv->re_regs->re_version_id),
> -		 in_be32(&re_priv->re_regs->global_config),
> -		 in_be32(&re_priv->re_regs->galois_field_config));
> +		 in_be32(&re_regs->re_version_id),
> +		 in_be32(&re_regs->global_config),
> +		 in_be32(&re_regs->galois_field_config));
>
>  	dma_dev = &re_priv->dma_dev;
>  	dma_dev->dev = dev;
> diff --git a/drivers/dma/fsl_raid.h b/drivers/dma/fsl_raid.h
> index 69d743c04973..adbfede330a7 100644
> --- a/drivers/dma/fsl_raid.h
> +++ b/drivers/dma/fsl_raid.h
> @@ -256,7 +256,7 @@ struct fsl_re_hw_desc {
>  struct fsl_re_drv_private {
>  	u8 total_chans;
>  	struct dma_device dma_dev;
> -	struct fsl_re_ctrl *re_regs;
> +	void __iomem *base;
>  	struct fsl_re_chan *re_jrs[FSL_RE_MAX_CHANS];
>  	struct dma_pool *cf_desc_pool;
>  	struct dma_pool *hw_desc_pool;
> @@ -273,7 +273,7 @@ struct fsl_re_chan {
>  	struct device *dev;
>  	struct fsl_re_drv_private *re_dev;
>  	struct dma_chan chan;
> -	struct fsl_re_chan_cfg *jrregs;
> +	struct fsl_re_chan_cfg __iomem *jrregs;
>  	int irq;
>  	struct tasklet_struct irqtask;
>  	u32 alloc_count;
> --
> 2.55.0
>