Op 18-08-2021 om 11:33 schreef Andy Shevchenko:
On Tue, Aug 17, 2021 at 06:28:59PM -0700, Jack Pham wrote:
On Thu, Aug 12, 2021 at 01:26:35AM -0700, Jack Pham wrote:
On DWC_usb3 revisions 3.00a and newer (including DWC_usb31 and
DWC_usb32) the GUCTL1 register gained the DEV_DECOUPLE_L1L2_EVT
field (bit 31) which when enabled allows the controller in device
mode to treat USB 2.0 L1 LPM & L2 events separately.
After commit d1d90dd27254 ("usb: dwc3: gadget: Enable suspend
events") the controller will now receive events (and therefore
interrupts) for every state change when entering/exiting either
L1 or L2 states. Since L1 is handled entirely by the hardware
and requires no software intervention, there is no need to even
enable these events and unnecessarily notify the gadget driver.
Enable the aforementioned bit to help reduce the overall interrupt
count for these L1 events that don't need to be handled while
retaining the events for full L2 suspend/wakeup.
Hi folks in To:
I'd like to request if any of you could help test this patch on your
boards to help make sure it doesn't cause any regressions since I know
some of the recent dwc3 patches from Qualcomm have been found to break
other devices :(. So I'm hoping to avoid that even for a patch as
small as this.
Hoping this could be tried out on boards/SoCs such as db845c, hikey960,
Exynos, the Intel "lakes", etc. Ideally this needs validation with a
high-speed connection to a USB 3.x host, which increases the chances
that USB 2.0 Link Power Management is supported.
Merrifield: We currently have
PROPERTY_ENTRY_BOOL("snps,usb2-gadget-lpm-disable")
Should I retest with this reverted?
The overall goal of this patch is to eliminate events generated for
L1 entry/exit, so we should see a slight reduction in interrupt counts
when checking `grep dwc3 /proc/interrupts` for comparable traffic.
I didn't compare interrupts
Unfortunately I'm quite busy lately with more important stuff and I dunno if I
will be able to test this in reasonable time. So, if Ferry volunteers, then we
can cover Intel Merrifield platform as well.
Performance unchanged, no regressions found.
Tested-by: Ferry Toth <fntoth@xxxxxxxxx> # for Merrifield
