Hi, On Fri, Nov 20, 2015 at 8:49 AM, Doug Anderson <dianders at chromium.org> wrote: > Felipe, > > On Fri, Nov 20, 2015 at 7:40 AM, Felipe Balbi <balbi at ti.com> wrote: >> >> Hi, >> >> Douglas Anderson <dianders at chromium.org> writes: >>> In general it is wise to clear interrupts before processing them. If >>> you don't do that, you can get: >>> 1. Interrupt happens >>> 2. You look at system state and process interrupt >>> 3. A new interrupt happens >>> 4. You clear interrupt without processing it. >>> >>> This patch was actually a first attempt to fix missing device insertions >>> as described in (usb: dwc2: host: Fix missing device insertions) and it >>> did solve some of the signal bouncing problems but not all of >>> them (which is why I submitted the other patch). Specifically, this >>> patch itself would sometimes change: >>> 1. hardware sees connect >>> 2. hardware sees disconnect >>> 3. hardware sees connect >>> 4. dwc2_port_intr() - clears connect interrupt >>> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect() >>> >>> ...to: >>> 1. hardware sees connect >>> 2. hardware sees disconnect >>> 3. dwc2_port_intr() - clears connect interrupt >>> 4. hardware sees connect >>> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect() >>> >>> ...but with different timing then sometimes we'd still miss cable >>> insertions. >>> >>> In any case, though this patch doesn't fix any (known) problems, it >>> still seems wise as a general policy to clear interrupt before handling >>> them. >>> >>> Note that for dwc2_handle_usb_port_intr(), instead of moving the clear >>> of PRTINT to the beginning of the function we remove it completely. The >>> only way to clear PRTINT is to clear the sources that set it in the >>> first place. >>> >>> Signed-off-by: Douglas Anderson <dianders at chromium.org> >>> Acked-by: John Youn <johnyoun at synopsys.com> >>> Tested-by: John Youn <johnyoun at synopsys.com> >> >> $ patch -p1 --dry-run < patch.diff >> checking file drivers/usb/dwc2/core_intr.c >> checking file drivers/usb/dwc2/hcd_intr.c >> Hunk #4 FAILED at 365. >> Hunk #5 succeeded at 388 (offset 11 lines). >> 1 out of 5 hunks FAILED >> >> Care to rebase on top of my testing/next ? > > No problem. > > ...though when I did that, I actually found (by code inspection) a bug > in the original patch, so I guess it's a good thing it didn't apply... > ...and then that led me to another bug that was pre-existing. I'll > send up two new patches shortly. I'll remove John's Ack and Tested > tags from the patch since it contains a change. > > It looks like you already landed part 1 of this series (usb: dwc2: > host: Fix missing device insertions) so I won't resend that. Ah, OK. Now I see why nobody found these problems in testing. The code path is completely disabled by all current parameters as checked in to mainline. In any case, it's good to fix. -Doug
