8000 v2 dwc2 DMA alignment_buffer handling by P33M · Pull Request #6923 · raspberrypi/linux · GitHub
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v2 dwc2 DMA alignment_buffer handling #6923

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Merged
merged 2 commits into from
Jun 24, 2025
+20 −14
Merged

v2 dwc2 DMA alignment_buffer handling #6923

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8831aac
Revert "usb: dwc2: use temporary URB buffer for small control transfers"
P33M Jun 23, 2025
53e2770
drivers: dwc2: better handle hardware length & alignment issues
P33M Jun 23, 2025
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Revert "usb: dwc2: use temporary URB buffer for small control transfers" 
This incorrectly matches on urb->setup_packet instead of checking the
pipe type, so recycled URBs were incorrectly matched.

A more comprehensive fix is forthcoming.

This reverts commit 2f27224.

Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
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@P33M
P33M committed Jun 23, 2025
commit 8831aac19c06a4db91a8b1d4d71e1d405fda1c57
19 changes: 3 additions & 16 deletions drivers/usb/dwc2/hcd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2469,23 +2469,10 @@ static int dwc2_alloc_dma_aligned_buffer(struct urb *urb, gfp_t mem_flags)
{
void *kmalloc_ptr;
size_t kmalloc_size;
bool small_ctrl;

if (urb->num_sgs || urb->sg || urb->transfer_buffer_length == 0)
return 0;

/*
* Hardware bug: small IN packets with length < 4 cause a
* 4-byte write to memory. This is only an issue for drivers that
* insist on packing a device's various properties into a struct
* and filling them one at a time with Control transfers (uvcvideo).
* Force the use of align_buf so that the subsequent memcpy puts
* the right number of bytes in the URB's buffer.
*/
small_ctrl = (urb->setup_packet &&
le16_to_cpu(((struct usb_ctrlrequest *)(urb->setup_packet))->wLength) < 4);

if (!small_ctrl && !((uintptr_t)urb->transfer_buffer & (DWC2_USB_DMA_ALIGN - 1)))
if (urb->num_sgs || urb->sg ||
urb->transfer_buffer_length == 0 ||
!((uintptr_t)urb->transfer_buffer & (DWC2_USB_DMA_ALIGN - 1)))
return 0;

/*
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