[PATCH 1/3] net: designware: Disable DMA on removal

[Heinrich Schuchardt]

Am 6. April 2025 00:12:45 MESZ schrieb Simon Glass <sjg at chromium.org>:
>At present, removing the device frees struct dw_eth_dev but does not
>disable DMA. When DMA is active, packets can be received even if the
>driver is not active.
>
>While it is possible that the memory used by the struct may remain
>untouched after removal, any other allocation may reuse that memory
>and result in DMA writing to random addresses.
>
>In most case U-Boot does this removal in announce_and_cleanup()
>immediately before jumping to the OS. No further allocations are done
>after that point.
>
>But with EFI_LOADER this function is not called before jumping to the
>EFI app. U-Boot continues to run while GRUB starts and finishes, as well
>as while Linux is starting up. During this time, devices cannot be
>removed, as they are in use. U-Boot completes the removal when
>efi_exit_boot_services() is called. It seems that this function does
>more allocations after calling dm_remove_devices_active() although I
>can't figure out where.
>
>Fix this by disabling DMA when the driver is removed.
>
>Signed-off-by: Simon Glass <sjg at chromium.org>
>Reported-by: Christian Kohlschütter <christian at kohlschutter.com>

LGTM

Acked-by: Heinrich Schuchardt <xypron.glpk at gmx.de>


>---
>
> drivers/net/designware.c | 1 +
> 1 file changed, 1 insertion(+)
>
>diff --git a/drivers/net/designware.c b/drivers/net/designware.c
>index 07b0f49ef58..eebf14bd51a 100644
>--- a/drivers/net/designware.c
>+++ b/drivers/net/designware.c
>@@ -809,6 +809,7 @@ static int designware_eth_remove(struct udevice *dev)
> {
> 	struct dw_eth_dev *priv = dev_get_priv(dev);
> 
>+	_dw_eth_halt(priv);
> 	free(priv->phydev);
> 	mdio_unregister(priv->bus);
> 	mdio_free(priv->bus);