Re: [PATCH] crypto: caam: map job ring registers without claiming region

[Richard Leitner <richard.leitner@linux.dev>]

Hi Rosen,

On Tue, Sep 01, 2026 at 01:37:36PM -0700, Rosen Penev wrote:
> devm_platform_ioremap_resource() ends up calling request_mem_region(),
> which fails with -EBUSY on i.MX SoCs:
> 
> There the job rings are modelled as sub-regions of their parent
> fsl,sec-v4.0 register window, and caam_probe() already reserves the
> whole window exclusively via devm_of_iomap() before the children are
> populated.  Every job ring therefore collides with its own parent and
> fails to probe, taking the hardware RNG offline (seen on i.MX6, i.MX7
> and i.MX8 boards such as colibri-imx7 and verdin-imx8mp).
> 
> Map the job ring registers with devm_ioremap() instead, which does not
> claim the (already owned) region.
> 
> Fixes: 9a955c0a7d11 ("crypto: caam - simplify probe resource and IRQ handling")
> Assisted-by: opencode:big-pickle
> Signed-off-by: Rosen Penev <rosenp@gmail.com>

thanks for that fix!

Tested-by: Richard Leitner <richard.leitner@linux.dev> # i.MX8MP

regards;rl

> ---
>  drivers/crypto/caam/jr.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/crypto/caam/jr.c b/drivers/crypto/caam/jr.c
> index f9e029945b51..2ed8229d4733 100644
> --- a/drivers/crypto/caam/jr.c
> +++ b/drivers/crypto/caam/jr.c
> @@ -583,12 +583,29 @@ static int caam_jr_probe(struct platform_device *pdev)
>  	struct caam_drv_private_jr *jrpriv;
>  	static int total_jobrs;
>  	void __iomem *ctrl;
> +	struct resource *r;
>  	int error;
>  	int irq;
>  
> -	ctrl = devm_platform_ioremap_resource(pdev, 0);
> -	if (IS_ERR(ctrl))
> -		return PTR_ERR(ctrl);
> +	/*
> +	 * The job rings live inside the register window of their parent
> +	 * fsl,sec-v4.0 node, which caam_probe() already reserves (and maps)
> +	 * via devm_of_iomap().  A requested region that overlaps that
> +	 * reservation, e.g. from devm_platform_ioremap_resource(), would
> +	 * therefore fail with -EBUSY, so map the registers without claiming
> +	 * the region here.
> +	 */
> +	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!r) {
> +		dev_err(&pdev->dev, "platform_get_resource() failed\n");
> +		return -EINVAL;
> +	}
> +
> +	ctrl = devm_ioremap(&pdev->dev, r->start, resource_size(r));
> +	if (!ctrl) {
> +		dev_err(&pdev->dev, "devm_ioremap() failed\n");
> +		return -ENOMEM;
> +	}
>  
>  	irq = platform_get_irq(pdev, 0);
>  	if (irq < 0)
> -- 
> 2.55.0
> 
>