Re: [PATCH] irqchip/qcom-pdc: Workaround hardware register bug on X1E80100

Dmitry Baryshkov
2025-02-13T22:14:43Z

On Thu, Feb 13, 2025 at 06:04:00PM +0100, Stephan Gerhold wrote:
> On X1E80100, there is a hardware bug in the register logic of the
> IRQ_ENABLE_BANK register. While read accesses work on the normal address,
> all write accesses must be made to a shifted address. Without a workaround
> for this, the wrong interrupt gets enabled in the PDC and it is impossible
> to wakeup from deep suspend (CX collapse).
>
> This has not caused problems so far, because the deep suspend state was not
> enabled. We need a workaround now since work is ongoing to fix this.
>
> Introduce a workaround for the problem by matching the qcom,x1e80100-pdc
> compatible and shift the write address by the necessary offset.
>
> Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
> ---
> drivers/irqchip/qcom-pdc.c | 51 +++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 48 insertions(+), 3 deletions(-)
>
> @@ -324,10 +357,21 @@ static int qcom_pdc_init(struct device_node *node, struct device_node *parent)
> if (res_size > resource_size(&res))
> pr_warn("%pOF: invalid reg size, please fix DT\n", node);
>
> + if (of_device_is_compatible(node, "qcom,x1e80100-pdc")) {
> + pdc_drv1 = ioremap(res.start - PDC_DRV_OFFSET, IRQ_ENABLE_BANK_MAX);

Please mention it in the commit message that you are mapping the memory
outside of the defined device's region.

> + if (!pdc_drv1) {
> + pr_err("%pOF: unable to map PDC DRV1 region\n", node);
> + return -ENXIO;
> + }
> +
> + pdc_x1e_quirk = true;
> + }
> +
> pdc_base = ioremap(res.start, res_size);
> if (!pdc_base) {
> pr_err("%pOF: unable to map PDC registers\n", node);
> - return -ENXIO;
> + ret = -ENXIO;
> + goto fail;
> }
>
> pdc_version = pdc_reg_read(PDC_VERSION_REG, 0);
> @@ -363,6 +407,7 @@ static int qcom_pdc_init(struct device_node *node, struct device_node *parent)
> fail:
> kfree(pdc_region);
> iounmap(pdc_base);
> + iounmap(pdc_drv1);
> return ret;
> }
>
>
> ---
> base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
> change-id: 20250211-x1e80100-pdc-hw-wa-b738d99ef459
>
> Best regards,
> --
> Stephan Gerhold <stephan.gerhold@linaro.org>
>

--
With best wishes
Dmitry