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Code Issues Releases Activity

Add helper function to check if a USB page cache buffer is properly

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aligned to reduce the use of bounce buffers in PIO mode.

MFC after:	1 week
This commit is contained in:
Hans Petter Selasky 2015-11-07 11:40:35 +00:00
parent ddd208f7ad
commit c6b6f54640
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=290489
2 changed files with 32 additions and 0 deletions
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29
sys/dev/usb/usb_busdma.c
View File

@ -133,6 +133,35 @@ usbd_get_page(struct usb_page_cache *pc, usb_frlength_t offset,
#endif
}
/*------------------------------------------------------------------------*
* usb_pc_buffer_is_aligned - verify alignment
*
* This function is used to check if a page cache buffer is properly
* aligned to reduce the use of bounce buffers in PIO mode.
*------------------------------------------------------------------------*/
uint8_t
usb_pc_buffer_is_aligned(struct usb_page_cache *pc, usb_frlength_t offset,
usb_frlength_t len, usb_frlength_t mask)
{
struct usb_page_search buf_res;
while (len != 0) {
usbd_get_page(pc, offset, &buf_res);
if (buf_res.length > len)
buf_res.length = len;
if (USB_P2U(buf_res.buffer) & mask)
return (0);
if (buf_res.length & mask)
return (0);
offset += buf_res.length;
len -= buf_res.length;
}
return (1);
}
/*------------------------------------------------------------------------*
* usbd_copy_in - copy directly to DMA-able memory
*------------------------------------------------------------------------*/

3
sys/dev/usb/usb_busdma.h
View File

@ -159,5 +159,8 @@ void usb_pc_cpu_flush(struct usb_page_cache *pc);
void usb_pc_cpu_invalidate(struct usb_page_cache *pc);
void usb_pc_dmamap_destroy(struct usb_page_cache *pc);
void usb_pc_free_mem(struct usb_page_cache *pc);
uint8_t usb_pc_buffer_is_aligned(struct usb_page_cache *pc,
usb_frlength_t offset, usb_frlength_t len,
usb_frlength_t mask);
#endif /* _USB_BUSDMA_H_ */