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

Nathan Lynch via B4 Relay
2026-04-10T13:07:50Z

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@amd.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Signed-off-by: Nathan Lynch <nathan.lynch@amd.com>
---
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(-)

diff --git a/drivers/dma/sdxi/device.c b/drivers/dma/sdxi/device.c
index 636abc410dcd..145aa098c269 100644
--- a/drivers/dma/sdxi/device.c
+++ b/drivers/dma/sdxi/device.c
@@ -67,6 +67,49 @@ static void sdxi_write_fn_gsr(struct sdxi_dev *sdxi, enum sdxi_fn_gsr cmd)
sdxi_write64(sdxi, SDXI_MMIO_CTL0, ctl0);
}

+static int sdxi_dev_start(struct sdxi_dev *sdxi)
+{
+ unsigned long deadline;
+ enum sdxi_fn_gsv status;
+
+ status = sdxi_dev_gsv(sdxi);
+ if (status != SDXI_GSV_STOP) {
+ sdxi_err(sdxi,
+ "can't activate busy device (unexpected gsv: %s)\n",
+ gsv_str(status));
+ return -EIO;
+ }
+
+ 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));
+
+ 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