Re: [PATCH 09/23] dmaengine: sdxi: Start functions on probe, stop on remove

[Frank Li]

On Fri, Apr 10, 2026 at 08:07:19AM -0500, Nathan Lynch wrote:
> Following admin context setup in the previous patch, drive each SDXI
> function to active state during probe. This is done by writing
> GSRV_ACTIVE to MMIO_CTL0.fn_gsr and polling MMIO_STS0.fn_gsv until the
> function reaches GSV_ACTIVE or an error state. A 1-second timeout has
> been sufficient in practice so far.
>
> Introduce sdxi_unregister() to stop the function during remove and wire
> it up via the pci_driver .remove callback.
>
> Co-developed-by: Wei Huang <wei.huang2@xxxxxxx>
> Signed-off-by: Wei Huang <wei.huang2@xxxxxxx>
> Signed-off-by: Nathan Lynch <nathan.lynch@xxxxxxx>
> ---
>  drivers/dma/sdxi/device.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++-
>  drivers/dma/sdxi/pci.c    |  6 +++++
>  drivers/dma/sdxi/sdxi.h   |  1 +
>  3 files changed, 62 insertions(+), 1 deletion(-)

...
> +
> +	sdxi_write_fn_gsr(sdxi, SDXI_GSRV_ACTIVE);
> +
> +	deadline = jiffies + msecs_to_jiffies(1000);
> +	do {
> +		status = sdxi_dev_gsv(sdxi);
> +		sdxi_dbg(sdxi, "%s: function state: %s\n", __func__, gsv_str(status));
> +
> +		switch (status) {
> +		case SDXI_GSV_ACTIVE:
> +			sdxi_dbg(sdxi, "activated\n");
> +			return 0;
> +		case SDXI_GSV_ERROR:
> +			sdxi_err(sdxi, "went to error state\n");
> +			return -EIO;
> +		case SDXI_GSV_INIT:
> +		case SDXI_GSV_STOP:
> +			/* transitional states, wait */
> +			fsleep(1000);
> +			break;
> +		default:
> +			sdxi_err(sdxi, "unexpected gsv %u, giving up\n", status);
> +			return -EIO;
> +		}
> +	} while (time_before(jiffies, deadline));

suppose read_poll_timeout() should work

Frank

> +
> +	sdxi_err(sdxi, "activation timed out, current status %u\n",
> +		sdxi_dev_gsv(sdxi));
> +	return -ETIMEDOUT;
> +}
> +
>  /* Get the device to the GSV_STOP state. */
>  static int sdxi_dev_stop(struct sdxi_dev *sdxi)
>  {
> @@ -197,7 +240,11 @@ static int sdxi_fn_activate(struct sdxi_dev *sdxi)
>  	if (err)
>  		return err;
>
> -	return 0;
> +	/*
> +	 * SDXI 1.0 4.1.8.9: Set MMIO_CTL0.fn_gsr to GSRV_ACTIVE and
> +	 * wait for MMIO_STS0.fn_gsv to reach GSV_ACTIVE or GSV_ERROR.
> +	 */
> +	return sdxi_dev_start(sdxi);
>  }
>
>  static int sdxi_create_dma_pool(struct sdxi_dev *sdxi, struct dma_pool **pool,
> @@ -250,3 +297,10 @@ int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops)
>
>  	return sdxi_device_init(sdxi);
>  }
> +
> +void sdxi_unregister(struct device *dev)
> +{
> +	struct sdxi_dev *sdxi = dev_get_drvdata(dev);
> +
> +	sdxi_dev_stop(sdxi);
> +}
> diff --git a/drivers/dma/sdxi/pci.c b/drivers/dma/sdxi/pci.c
> index f3f8485e50e3..8e4dfde078ff 100644
> --- a/drivers/dma/sdxi/pci.c
> +++ b/drivers/dma/sdxi/pci.c
> @@ -67,6 +67,11 @@ static int sdxi_pci_probe(struct pci_dev *pdev,
>  	return sdxi_register(&pdev->dev, &sdxi_pci_ops);
>  }
>
> +static void sdxi_pci_remove(struct pci_dev *pdev)
> +{
> +	sdxi_unregister(&pdev->dev);
> +}
> +
>  static const struct pci_device_id sdxi_id_table[] = {
>  	{ PCI_DEVICE_CLASS(PCI_CLASS_ACCELERATOR_SDXI, 0xffffff) },
>  	{ }
> @@ -77,6 +82,7 @@ static struct pci_driver sdxi_driver = {
>  	.name = "sdxi",
>  	.id_table = sdxi_id_table,
>  	.probe = sdxi_pci_probe,
> +	.remove = sdxi_pci_remove,
>  	.sriov_configure = pci_sriov_configure_simple,
>  };
>
> diff --git a/drivers/dma/sdxi/sdxi.h b/drivers/dma/sdxi/sdxi.h
> index bbc14364a5c9..426101875334 100644
> --- a/drivers/dma/sdxi/sdxi.h
> +++ b/drivers/dma/sdxi/sdxi.h
> @@ -75,6 +75,7 @@ static inline struct device *sdxi_to_dev(const struct sdxi_dev *sdxi)
>  #define sdxi_err(s, fmt, ...) dev_err(sdxi_to_dev(s), fmt, ## __VA_ARGS__)
>
>  int sdxi_register(struct device *dev, const struct sdxi_bus_ops *ops);
> +void sdxi_unregister(struct device *dev);
>
>  static inline u64 sdxi_read64(const struct sdxi_dev *sdxi, enum sdxi_reg reg)
>  {
>
> --
> 2.53.0
>