[v4,0/2] usb: xhci: page size improvements

Message

Neronin, Niklas Feb. 20, 2025, 2:40 p.m. UTC

Correct off-by-one page size debug message.
Set page size to the xHCI-supported size, instead of 4KB.

Clarified the interpretation of the xHCI spec 1.9 regarding page size.
The correct interpretation is that only one bit is set, indicating the
only supported page size. This is supported by the following sources:

Section 6.6.1, PSZ:
  The PSZ calculation uses the page size bit and would not work with
  multiple bits set.

Section 7.7, Implementation Notes:
  "This version of the xHCI spec only allows an implementation to support
   a single page size, as reported by the PAGESIZE register."

Version 4 changes:
 * Replace manual power of 2 check with is_power_of_2()
Version 3 changes:
 * Rebase agains Linux 6.14-rc1.
 * Repalce variable int 'i' with unsigned int 'val'.
 * Rename temp variable 'page_shift' to 'page_size'.
Version 2 changes:
 * Added handling for invalid page size register values.

Niklas Neronin (2):
  usb: xhci: correct debug message page size calculation
  usb: xhci: set page size to the xHCI-supported size

 drivers/usb/host/xhci-mem.c | 34 ++++++++++++++++++----------------
 drivers/usb/host/xhci.h     |  8 ++++----
 2 files changed, 22 insertions(+), 20 deletions(-)