mirror of https://github.com/hak5/openwrt-owl.git
kernel: usb: dwc2 DMA alignment fixes
Add two patches submitted for upstream review that significantly improve the dwc2 driver on openwrt from kernel stability and performance perspectives. Fixes: FS#1367 Signed-off-by: Antti Seppälä <a.seppala@gmail.com>master
Antti Seppälä
Hauke Mehrtens
parent
c79ef6fbe3
commit
9f451ec698
|
|
@ -0,0 +1,126 @@
|
|||
From 028c9191bdf88f120f65626920a6a679170fcc3e Mon Sep 17 00:00:00 2001
|
||||
From: =?UTF-8?q?Antti=20Sepp=C3=A4l=C3=A4?= <a.seppala@gmail.com>
|
||||
Date: Thu, 5 Jul 2018 11:37:03 +0300
|
||||
Subject: [PATCH 1/2] usb: dwc2: Fix DMA alignment to start at allocated
|
||||
boundary
|
||||
MIME-Version: 1.0
|
||||
Content-Type: text/plain; charset=UTF-8
|
||||
Content-Transfer-Encoding: 8bit
|
||||
|
||||
The commit 3bc04e28a030 ("usb: dwc2: host: Get aligned DMA in a more
|
||||
supported way") introduced a common way to align DMA allocations.
|
||||
The code in the commit aligns the struct dma_aligned_buffer but the
|
||||
actual DMA address pointed by data[0] gets aligned to an offset from
|
||||
the allocated boundary by the kmalloc_ptr and the old_xfer_buffer
|
||||
pointers.
|
||||
|
||||
This is against the recommendation in Documentation/DMA-API.txt which
|
||||
states:
|
||||
|
||||
Therefore, it is recommended that driver writers who don't take
|
||||
special care to determine the cache line size at run time only map
|
||||
virtual regions that begin and end on page boundaries (which are
|
||||
guaranteed also to be cache line boundaries).
|
||||
|
||||
The effect of this is that architectures with non-coherent DMA caches
|
||||
may run into memory corruption or kernel crashes with Unhandled
|
||||
kernel unaligned accesses exceptions.
|
||||
|
||||
Fix the alignment by positioning the DMA area in front of the allocation
|
||||
and use memory at the end of the area for storing the orginal
|
||||
transfer_buffer pointer. This may have the added benefit of increased
|
||||
performance as the DMA area is now fully aligned on all architectures.
|
||||
|
||||
Tested with Lantiq xRX200 (MIPS) and RPi Model B Rev 2 (ARM).
|
||||
|
||||
Fixes: 3bc04e28a030 ("usb: dwc2: host: Get aligned DMA in a more
|
||||
supported way")
|
||||
|
||||
Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
|
||||
---
|
||||
drivers/usb/dwc2/hcd.c | 44 +++++++++++++++++++++++---------------------
|
||||
1 file changed, 23 insertions(+), 21 deletions(-)
|
||||
|
||||
--- a/drivers/usb/dwc2/hcd.c
|
||||
+++ b/drivers/usb/dwc2/hcd.c
|
||||
@@ -2628,34 +2628,29 @@ static void dwc2_hc_init_xfer(struct dwc
|
||||
|
||||
#define DWC2_USB_DMA_ALIGN 4
|
||||
|
||||
-struct dma_aligned_buffer {
|
||||
- void *kmalloc_ptr;
|
||||
- void *old_xfer_buffer;
|
||||
- u8 data[0];
|
||||
-};
|
||||
-
|
||||
static void dwc2_free_dma_aligned_buffer(struct urb *urb)
|
||||
{
|
||||
- struct dma_aligned_buffer *temp;
|
||||
+ void *stored_xfer_buffer;
|
||||
|
||||
if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
|
||||
return;
|
||||
|
||||
- temp = container_of(urb->transfer_buffer,
|
||||
- struct dma_aligned_buffer, data);
|
||||
+ /* Restore urb->transfer_buffer from the end of the allocated area */
|
||||
+ memcpy(&stored_xfer_buffer, urb->transfer_buffer +
|
||||
+ urb->transfer_buffer_length, sizeof(urb->transfer_buffer));
|
||||
|
||||
if (usb_urb_dir_in(urb))
|
||||
- memcpy(temp->old_xfer_buffer, temp->data,
|
||||
+ memcpy(stored_xfer_buffer, urb->transfer_buffer,
|
||||
urb->transfer_buffer_length);
|
||||
- urb->transfer_buffer = temp->old_xfer_buffer;
|
||||
- kfree(temp->kmalloc_ptr);
|
||||
+ kfree(urb->transfer_buffer);
|
||||
+ urb->transfer_buffer = stored_xfer_buffer;
|
||||
|
||||
urb->transfer_flags &= ~URB_ALIGNED_TEMP_BUFFER;
|
||||
}
|
||||
|
||||
static int dwc2_alloc_dma_aligned_buffer(struct urb *urb, gfp_t mem_flags)
|
||||
{
|
||||
- struct dma_aligned_buffer *temp, *kmalloc_ptr;
|
||||
+ void *kmalloc_ptr;
|
||||
size_t kmalloc_size;
|
||||
|
||||
if (urb->num_sgs || urb->sg ||
|
||||
@@ -2663,22 +2658,29 @@ static int dwc2_alloc_dma_aligned_buffer
|
||||
!((uintptr_t)urb->transfer_buffer & (DWC2_USB_DMA_ALIGN - 1)))
|
||||
return 0;
|
||||
|
||||
- /* Allocate a buffer with enough padding for alignment */
|
||||
+ /*
|
||||
+ * Allocate a buffer with enough padding for original transfer_buffer
|
||||
+ * pointer. This allocation is guaranteed to be aligned properly for
|
||||
+ * DMA
|
||||
+ */
|
||||
kmalloc_size = urb->transfer_buffer_length +
|
||||
- sizeof(struct dma_aligned_buffer) + DWC2_USB_DMA_ALIGN - 1;
|
||||
+ sizeof(urb->transfer_buffer);
|
||||
|
||||
kmalloc_ptr = kmalloc(kmalloc_size, mem_flags);
|
||||
if (!kmalloc_ptr)
|
||||
return -ENOMEM;
|
||||
|
||||
- /* Position our struct dma_aligned_buffer such that data is aligned */
|
||||
- temp = PTR_ALIGN(kmalloc_ptr + 1, DWC2_USB_DMA_ALIGN) - 1;
|
||||
- temp->kmalloc_ptr = kmalloc_ptr;
|
||||
- temp->old_xfer_buffer = urb->transfer_buffer;
|
||||
+ /*
|
||||
+ * Position value of original urb->transfer_buffer pointer to the end
|
||||
+ * of allocation for later referencing
|
||||
+ */
|
||||
+ memcpy(kmalloc_ptr + urb->transfer_buffer_length,
|
||||
+ &urb->transfer_buffer, sizeof(urb->transfer_buffer));
|
||||
+
|
||||
if (usb_urb_dir_out(urb))
|
||||
- memcpy(temp->data, urb->transfer_buffer,
|
||||
+ memcpy(kmalloc_ptr, urb->transfer_buffer,
|
||||
urb->transfer_buffer_length);
|
||||
- urb->transfer_buffer = temp->data;
|
||||
+ urb->transfer_buffer = kmalloc_ptr;
|
||||
|
||||
urb->transfer_flags |= URB_ALIGNED_TEMP_BUFFER;
|
||||
|
||||
|
|
@ -0,0 +1,50 @@
|
|||
From 81da1738eee68f1961e03bdeb2d60cf0eb4dd713 Mon Sep 17 00:00:00 2001
|
||||
From: =?UTF-8?q?Antti=20Sepp=C3=A4l=C3=A4?= <a.seppala@gmail.com>
|
||||
Date: Thu, 5 Jul 2018 12:06:18 +0300
|
||||
Subject: [PATCH 2/2] usb: dwc2: Fix inefficient copy of unaligned buffers
|
||||
MIME-Version: 1.0
|
||||
Content-Type: text/plain; charset=UTF-8
|
||||
Content-Transfer-Encoding: 8bit
|
||||
|
||||
Make sure only to copy any actual data rather than the whole buffer,
|
||||
when releasing the temporary buffer used for unaligned non-isochronous
|
||||
transfers.
|
||||
|
||||
Taken directly from commit 0efd937e27d5e ("USB: ehci-tegra: fix inefficient
|
||||
copy of unaligned buffers")
|
||||
|
||||
Tested with Lantiq xRX200 (MIPS) and RPi Model B Rev 2 (ARM)
|
||||
|
||||
Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
|
||||
---
|
||||
drivers/usb/dwc2/hcd.c | 12 +++++++++---
|
||||
1 file changed, 9 insertions(+), 3 deletions(-)
|
||||
|
||||
--- a/drivers/usb/dwc2/hcd.c
|
||||
+++ b/drivers/usb/dwc2/hcd.c
|
||||
@@ -2631,6 +2631,7 @@ static void dwc2_hc_init_xfer(struct dwc
|
||||
static void dwc2_free_dma_aligned_buffer(struct urb *urb)
|
||||
{
|
||||
void *stored_xfer_buffer;
|
||||
+ size_t length;
|
||||
|
||||
if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
|
||||
return;
|
||||
@@ -2639,9 +2640,14 @@ static void dwc2_free_dma_aligned_buffer
|
||||
memcpy(&stored_xfer_buffer, urb->transfer_buffer +
|
||||
urb->transfer_buffer_length, sizeof(urb->transfer_buffer));
|
||||
|
||||
- if (usb_urb_dir_in(urb))
|
||||
- memcpy(stored_xfer_buffer, urb->transfer_buffer,
|
||||
- urb->transfer_buffer_length);
|
||||
+ if (usb_urb_dir_in(urb)) {
|
||||
+ if (usb_pipeisoc(urb->pipe))
|
||||
+ length = urb->transfer_buffer_length;
|
||||
+ else
|
||||
+ length = urb->actual_length;
|
||||
+
|
||||
+ memcpy(stored_xfer_buffer, urb->transfer_buffer, length);
|
||||
+ }
|
||||
kfree(urb->transfer_buffer);
|
||||
urb->transfer_buffer = stored_xfer_buffer;
|
||||
|
||||
Loading…
Reference in New Issue