Hi Shimoda-san,

CC linux-pm people

On Thu, Jan 17, 2019 at 9:48 AM Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com wrote:

From: Phuong Nguyen phuong.nguyen.xw@renesas.com

This commit fixes the issue that USB-DMAC hangs silently after system resumes on R-Car Gen3 hence renesas_usbhs will not work correctly when using USB-DMAC for bulk transfer e.g. ethernet or serial gadgets.

The issue can be reproduced by these steps:

1. modprobe g_serial
2. Suspend and resume system.
3. connect a usb cable to host side
4. Transfer data from Host to Target
5. cat /dev/ttyGS0 (Target side)
6. echo "test" > /dev/ttyACM0 (Host side)

The 'cat' will not result anything. However, system still can work normally.

Currently, USB-DMAC driver does not have system sleep callbacks hence this driver relies on the PM core to force runtime suspend/resume to suspend and reinitialize USB-DMAC during system resume. After the commit 17218e0092f8 ("PM / genpd: Stop/start devices without pm_runtime_force_suspend/resume()"), PM core will not force runtime suspend/resume anymore so this issue happens.

To solve this, make system suspend resume explicit by using pm_runtime_force_{suspend,resume}() as the system sleep callbacks. SET_NOIRQ_SYSTEM_SLEEP_PM_OPS()is used to make sure USB-DMAC suspended after and initialized before renesas_usbhs."

Signed-off-by: Phuong Nguyen phuong.nguyen.xw@renesas.com Signed-off-by: Hiroyuki Yokoyama hiroyuki.yokoyama.vx@renesas.com Cc: stable@vger.kernel.org # v4.16+ [shimoda: revise the commit log and add Cc tag] Signed-off-by: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com

Thanks for your patch!

This is similar in spirit to commits 1131b0a4af911de5 ("dmaengine: rcar-dmac: Make DMAC reinit during system resume explicit") and 73dcc666d6bd0db5 ("dmaengine: rcar-dmac: Fix too early/late system suspend/resume callbacks") for rcar-dmac.

I'm only wondering if the "late" variant would be sufficient here. Does g_serial support wake-up? Anyway, using the "noirq" variant, like you did, is probably the safest.

Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be

---

drivers/dma/sh/usb-dmac.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c index 7f7184c..59403f6 100644 --- a/drivers/dma/sh/usb-dmac.c +++ b/drivers/dma/sh/usb-dmac.c @@ -694,6 +694,8 @@ static int usb_dmac_runtime_resume(struct device *dev) #endif /* CONFIG_PM */

static const struct dev_pm_ops usb_dmac_pm = {

•   SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
  

•                                 pm_runtime_force_resume)
    SET_RUNTIME_PM_OPS(usb_dmac_runtime_suspend, usb_dmac_runtime_resume,
                       NULL)
  

};

Gr{oetje,eeting}s,

Geert