On 2024-03-11 9:49 am, Howard Yen wrote:
The reason why it needs multiple regions is that in my system there is
an always-on subsystem which includes a small size memory, and several
functions need to run and occupy the memory from the small memory if
they need to run on the always-on subsystem. These functions must
allocate the memory from the small memory region, so that they can get
benefit from the always-on subsystem. So the small memory is split for
multiple functions which are satisfied with their generic use cases.
But in specific use cases, like USB3 devices which support the stream
trasnsfer or multiple devices connect to the host, they required more
memory than their pre-allocated memory region, so I tried to propose
this patch to give it the ability to get the memory from the other
larger memory to solve the issue.
Once again this still fails to make sense - The USB controller has a
special always-on pool from which it "must allocate", yet it's fine if
it also allocates from elsewhere? How on Earth is that supposed to work?
As I said before, if it's actually the case that only certain specific
allocations (based on driver-level knowledge) must come from the special
pool, then this is not something which can realistically be abstracted
by the generic dma-coherent API as it stands (and if so, do the
non-special allocations even need a dedicated second reserved region, or
is that in fact just a massive hack around the dma_coherent_mem design
intentionally not falling back to the regular allocator?)
Thanks,
Robin.
Signed-off-by: Howard Yen <howardyen@xxxxxxxxxx>
---
drivers/usb/host/xhci-plat.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 3d071b875308..7892d3eb26d2 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -14,6 +14,7 @@
#include <linux/pci.h>
#include <linux/of.h>
#include <linux/of_device.h>
+#include <linux/of_reserved_mem.h>
#include <linux/platform_device.h>
#include <linux/usb/phy.h>
#include <linux/slab.h>
@@ -149,7 +150,7 @@ int xhci_plat_probe(struct platform_device *pdev, struct device *sysdev, const s
struct xhci_hcd *xhci;
struct resource *res;
struct usb_hcd *hcd, *usb3_hcd;
- int ret;
+ int i, count, ret;
int irq;
struct xhci_plat_priv *priv = NULL;
bool of_match;
@@ -194,6 +195,19 @@ int xhci_plat_probe(struct platform_device *pdev, struct device *sysdev, const s
xhci->allow_single_roothub = 1;
+ count = of_property_count_u32_elems(sysdev->of_node, "memory-region");
+
+ for (i = 0; i < count; i++) {
+ ret = of_reserved_mem_device_init_by_idx(sysdev, sysdev->of_node, i);
+ if (ret) {
+ dev_err(sysdev, "Could not get reserved memory\n");
+ if (i > 0)
+ of_reserved_mem_device_release(sysdev);
+
+ return ret;
+ }
+ }
+
/*
* Not all platforms have clks so it is not an error if the
* clock do not exist.
@@ -431,6 +445,9 @@ void xhci_plat_remove(struct platform_device *dev)
clk_disable_unprepare(clk);
clk_disable_unprepare(reg_clk);
reset_control_assert(xhci->reset);
+
+ of_reserved_mem_device_release(hcd->self.sysdev);
+
usb_put_hcd(hcd);
pm_runtime_disable(&dev->dev);
